trace.h: Implement optional attribute lists

[libside.git] / include / side / trace.h

diff --git a/include/side/trace.h b/include/side/trace.h
index a5461fcde904c4f0100b99ff09c8591af25e98d4..f7bf90122cf5c4a4fffe5fedc99a9062c530d41e 100644 (file)
--- a/include/side/trace.h
+++ b/include/side/trace.h
@@ -11,11 +11,12 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <math.h>
+#include <stdbool.h>
 #include <side/macros.h>
 #include <side/endian.h>
 
 /*
- * SIDE stands for "Static Instrumentation Dynamically Enabled"
+ * SIDE stands for "Software Instrumentation Dynamically Enabled"
  *
  * This is an instrumentation API for Linux user-space, which exposes an
  * instrumentation type system and facilities allowing a kernel or
@@ -72,7 +73,7 @@
 
 struct side_arg;
 struct side_arg_vec;
-struct side_arg_dynamic;
+union side_arg_dynamic;
 struct side_arg_dynamic_field;
 struct side_arg_dynamic_vla;
 struct side_type;
@@ -82,6 +83,7 @@ struct side_tracer_dynamic_struct_visitor_ctx;
 struct side_event_description;
 struct side_arg_dynamic_struct;
 struct side_events_register_handle;
+struct side_arg_variant;
 
 enum side_type_label {
        /* Stack-copy basic types */
@@ -107,6 +109,7 @@ enum side_type_label {
 
        /* Stack-copy compound types */
        SIDE_TYPE_STRUCT,
+       SIDE_TYPE_VARIANT,
        SIDE_TYPE_ARRAY,
        SIDE_TYPE_VLA,
        SIDE_TYPE_VLA_VISITOR,
@@ -471,6 +474,7 @@ struct side_type {
                struct side_type_vla side_vla;
                struct side_type_vla_visitor side_vla_visitor;
                const struct side_type_struct *side_struct;
+               const struct side_type_variant *side_variant;
 
                /* Stack-copy enumeration types */
                struct side_type_enum side_enum;
@@ -481,6 +485,20 @@ struct side_type {
        } SIDE_PACKED u;
 } SIDE_PACKED;
 
+struct side_variant_option {
+       int64_t range_begin;
+       int64_t range_end;
+       const struct side_type side_type;
+} SIDE_PACKED;
+
+struct side_type_variant {
+       const struct side_type selector;
+       const struct side_variant_option *options;
+       const struct side_attr *attr;
+       uint32_t nr_options;
+       uint32_t nr_attr;
+} SIDE_PACKED;
+
 struct side_event_field {
        const char *field_name;
        struct side_type side_type;
@@ -503,7 +521,7 @@ struct side_callback {
        void *priv;
 } SIDE_PACKED;
 
-struct side_arg_static {
+union side_arg_static {
        /* Stack-copy basic types */
        union side_bool_value bool_value;
        uint8_t byte_value;
@@ -513,23 +531,24 @@ struct side_arg_static {
 
        /* Stack-copy compound types */
        const struct side_arg_vec *side_struct;
+       const struct side_arg_variant *side_variant;
        const struct side_arg_vec *side_array;
        const struct side_arg_vec *side_vla;
        void *side_vla_app_visitor_ctx;
 
        /* Gather basic types */
-       void *side_bool_gather_ptr;
-       void *side_byte_gather_ptr;
-       void *side_integer_gather_ptr;
-       void *side_float_gather_ptr;
-       void *side_string_gather_ptr;
+       const void *side_bool_gather_ptr;
+       const void *side_byte_gather_ptr;
+       const void *side_integer_gather_ptr;
+       const void *side_float_gather_ptr;
+       const void *side_string_gather_ptr;
 
        /* Gather compound types */
-       void *side_array_gather_ptr;
-       void *side_struct_gather_ptr;
+       const void *side_array_gather_ptr;
+       const void *side_struct_gather_ptr;
        struct {
-               void *ptr;
-               void *length_ptr;
+               const void *ptr;
+               const void *length_ptr;
        } SIDE_PACKED side_vla_gather;
 } SIDE_PACKED;
 
@@ -561,7 +580,7 @@ struct side_dynamic_vla_visitor {
        uint32_t nr_attr;
 } SIDE_PACKED;
 
-struct side_arg_dynamic {
+union side_arg_dynamic {
        /* Dynamic basic types */
        struct side_type_null side_null;
        struct {
@@ -596,11 +615,16 @@ struct side_arg_dynamic {
 struct side_arg {
        uint32_t type;  /* enum side_type_label */
        union {
-               struct side_arg_static side_static;
-               struct side_arg_dynamic side_dynamic;
+               union side_arg_static side_static;
+               union side_arg_dynamic side_dynamic;
        } SIDE_PACKED u;
 } SIDE_PACKED;
 
+struct side_arg_variant {
+       struct side_arg selector;
+       struct side_arg option;
+} SIDE_PACKED;
+
 struct side_arg_vec {
        const struct side_arg *sav;
        uint32_t len;
@@ -689,12 +713,12 @@ struct side_event_description {
 
 /* Stack-copy enumeration type definitions */
 
-#define side_define_enum(_identifier, _mappings, _attr) \
+#define side_define_enum(_identifier, _mappings, _attr...) \
        const struct side_enum_mappings _identifier = { \
                .mappings = _mappings, \
-               .attr = _attr, \
+               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
                .nr_mappings = SIDE_ARRAY_SIZE(SIDE_PARAM(_mappings)), \
-               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
        }
 
 #define side_enum_mapping_list(...) \
@@ -722,12 +746,12 @@ struct side_event_description {
                }, \
        }
 
-#define side_define_enum_bitmap(_identifier, _mappings, _attr) \
+#define side_define_enum_bitmap(_identifier, _mappings, _attr...) \
        const struct side_enum_bitmap_mappings _identifier = { \
                .mappings = _mappings, \
-               .attr = _attr, \
+               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
                .nr_mappings = SIDE_ARRAY_SIZE(SIDE_PARAM(_mappings)), \
-               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
        }
 
 #define side_enum_bitmap_mapping_list(...) \
@@ -757,24 +781,24 @@ struct side_event_description {
 
 /* Stack-copy field and type definitions */
 
-#define side_type_null(_attr) \
+#define side_type_null(_attr...) \
        { \
                .type = SIDE_TYPE_NULL, \
                .u = { \
                        .side_null = { \
-                               .attr = _attr, \
-                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                        }, \
                }, \
        }
 
-#define side_type_bool(_attr) \
+#define side_type_bool(_attr...) \
        { \
                .type = SIDE_TYPE_BOOL, \
                .u = { \
                        .side_bool = { \
-                               .attr = _attr, \
-                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                .bool_size = sizeof(uint8_t), \
                                .len_bits = 0, \
                                .byte_order = SIDE_TYPE_BYTE_ORDER_HOST, \
@@ -782,13 +806,13 @@ struct side_event_description {
                }, \
        }
 
-#define side_type_byte(_attr) \
+#define side_type_byte(_attr...) \
        { \
                .type = SIDE_TYPE_BYTE, \
                .u = { \
                        .side_byte = { \
-                               .attr = _attr, \
-                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                        }, \
                }, \
        }
@@ -845,102 +869,112 @@ struct side_event_description {
                .side_type = _type, \
        }
 
+#define side_option_range(_range_begin, _range_end, _type) \
+       { \
+               .range_begin = _range_begin, \
+               .range_end = _range_end, \
+               .side_type = _type, \
+       }
+
+#define side_option(_value, _type) \
+       side_option_range(_value, _value, SIDE_PARAM(_type))
+
 /* Host endian */
-#define side_type_u8(_attr)                            _side_type_integer(SIDE_TYPE_U8, false, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint8_t), 0, SIDE_PARAM(_attr))
-#define side_type_u16(_attr)                           _side_type_integer(SIDE_TYPE_U16, false, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint16_t), 0, SIDE_PARAM(_attr))
-#define side_type_u32(_attr)                           _side_type_integer(SIDE_TYPE_U32, false, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint32_t), 0, SIDE_PARAM(_attr))
-#define side_type_u64(_attr)                           _side_type_integer(SIDE_TYPE_U64, false, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint64_t), 0, SIDE_PARAM(_attr))
-#define side_type_s8(_attr)                            _side_type_integer(SIDE_TYPE_S8, true, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(int8_t), 0, SIDE_PARAM(_attr))
-#define side_type_s16(_attr)                           _side_type_integer(SIDE_TYPE_S16, true, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(int16_t), 0, SIDE_PARAM(_attr))
-#define side_type_s32(_attr)                           _side_type_integer(SIDE_TYPE_S32, true, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(int32_t), 0, SIDE_PARAM(_attr))
-#define side_type_s64(_attr)                           _side_type_integer(SIDE_TYPE_S64, true, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(int64_t), 0, SIDE_PARAM(_attr))
-#define side_type_pointer(_attr)                       _side_type_integer(SIDE_TYPE_POINTER, false, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uintptr_t), 0, SIDE_PARAM(_attr))
-#define side_type_float_binary16(_attr)                        _side_type_float(SIDE_TYPE_FLOAT_BINARY16, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, sizeof(_Float16), SIDE_PARAM(_attr))
-#define side_type_float_binary32(_attr)                        _side_type_float(SIDE_TYPE_FLOAT_BINARY32, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, sizeof(_Float32), SIDE_PARAM(_attr))
-#define side_type_float_binary64(_attr)                        _side_type_float(SIDE_TYPE_FLOAT_BINARY64, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, sizeof(_Float64), SIDE_PARAM(_attr))
-#define side_type_float_binary128(_attr)               _side_type_float(SIDE_TYPE_FLOAT_BINARY128, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, sizeof(_Float128), SIDE_PARAM(_attr))
-#define side_type_string(_attr)                                _side_type_string(SIDE_TYPE_STRING_UTF8, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint8_t), SIDE_PARAM(_attr))
-#define side_type_string16(_attr)                      _side_type_string(SIDE_TYPE_STRING_UTF16, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint16_t), SIDE_PARAM(_attr))
-#define side_type_string32(_attr)                      _side_type_string(SIDE_TYPE_STRING_UTF32, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint32_t), SIDE_PARAM(_attr))
-
-#define side_field_null(_name, _attr)                  _side_field(_name, side_type_null(SIDE_PARAM(_attr)))
-#define side_field_bool(_name, _attr)                  _side_field(_name, side_type_bool(SIDE_PARAM(_attr)))
-#define side_field_u8(_name, _attr)                    _side_field(_name, side_type_u8(SIDE_PARAM(_attr)))
-#define side_field_u16(_name, _attr)                   _side_field(_name, side_type_u16(SIDE_PARAM(_attr)))
-#define side_field_u32(_name, _attr)                   _side_field(_name, side_type_u32(SIDE_PARAM(_attr)))
-#define side_field_u64(_name, _attr)                   _side_field(_name, side_type_u64(SIDE_PARAM(_attr)))
-#define side_field_s8(_name, _attr)                    _side_field(_name, side_type_s8(SIDE_PARAM(_attr)))
-#define side_field_s16(_name, _attr)                   _side_field(_name, side_type_s16(SIDE_PARAM(_attr)))
-#define side_field_s32(_name, _attr)                   _side_field(_name, side_type_s32(SIDE_PARAM(_attr)))
-#define side_field_s64(_name, _attr)                   _side_field(_name, side_type_s64(SIDE_PARAM(_attr)))
-#define side_field_byte(_name, _attr)                  _side_field(_name, side_type_byte(SIDE_PARAM(_attr)))
-#define side_field_pointer(_name, _attr)               _side_field(_name, side_type_pointer(SIDE_PARAM(_attr)))
-#define side_field_float_binary16(_name, _attr)                _side_field(_name, side_type_float_binary16(SIDE_PARAM(_attr)))
-#define side_field_float_binary32(_name, _attr)                _side_field(_name, side_type_float_binary32(SIDE_PARAM(_attr)))
-#define side_field_float_binary64(_name, _attr)                _side_field(_name, side_type_float_binary64(SIDE_PARAM(_attr)))
-#define side_field_float_binary128(_name, _attr)       _side_field(_name, side_type_float_binary128(SIDE_PARAM(_attr)))
-#define side_field_string(_name, _attr)                        _side_field(_name, side_type_string(SIDE_PARAM(_attr)))
-#define side_field_string16(_name, _attr)              _side_field(_name, side_type_string16(SIDE_PARAM(_attr)))
-#define side_field_string32(_name, _attr)              _side_field(_name, side_type_string32(SIDE_PARAM(_attr)))
+#define side_type_u8(_attr...)                         _side_type_integer(SIDE_TYPE_U8, false, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint8_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_u16(_attr...)                                _side_type_integer(SIDE_TYPE_U16, false, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint16_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_u32(_attr...)                                _side_type_integer(SIDE_TYPE_U32, false, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint32_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_u64(_attr...)                                _side_type_integer(SIDE_TYPE_U64, false, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint64_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_s8(_attr...)                         _side_type_integer(SIDE_TYPE_S8, true, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(int8_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_s16(_attr...)                                _side_type_integer(SIDE_TYPE_S16, true, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(int16_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_s32(_attr...)                                _side_type_integer(SIDE_TYPE_S32, true, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(int32_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_s64(_attr...)                                _side_type_integer(SIDE_TYPE_S64, true, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(int64_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_pointer(_attr...)                    _side_type_integer(SIDE_TYPE_POINTER, false, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uintptr_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_float_binary16(_attr...)             _side_type_float(SIDE_TYPE_FLOAT_BINARY16, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, sizeof(_Float16), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_float_binary32(_attr...)             _side_type_float(SIDE_TYPE_FLOAT_BINARY32, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, sizeof(_Float32), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_float_binary64(_attr...)             _side_type_float(SIDE_TYPE_FLOAT_BINARY64, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, sizeof(_Float64), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_float_binary128(_attr...)            _side_type_float(SIDE_TYPE_FLOAT_BINARY128, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, sizeof(_Float128), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_string(_attr...)                     _side_type_string(SIDE_TYPE_STRING_UTF8, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint8_t), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_string16(_attr...)                   _side_type_string(SIDE_TYPE_STRING_UTF16, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint16_t), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_string32(_attr...)                   _side_type_string(SIDE_TYPE_STRING_UTF32, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint32_t), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+
+#define side_field_null(_name, _attr...)               _side_field(_name, side_type_null(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_bool(_name, _attr...)               _side_field(_name, side_type_bool(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_u8(_name, _attr...)                 _side_field(_name, side_type_u8(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_u16(_name, _attr...)                        _side_field(_name, side_type_u16(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_u32(_name, _attr...)                        _side_field(_name, side_type_u32(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_u64(_name, _attr...)                        _side_field(_name, side_type_u64(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_s8(_name, _attr...)                 _side_field(_name, side_type_s8(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_s16(_name, _attr...)                        _side_field(_name, side_type_s16(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_s32(_name, _attr...)                        _side_field(_name, side_type_s32(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_s64(_name, _attr...)                        _side_field(_name, side_type_s64(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_byte(_name, _attr...)               _side_field(_name, side_type_byte(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_pointer(_name, _attr...)            _side_field(_name, side_type_pointer(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_float_binary16(_name, _attr...)     _side_field(_name, side_type_float_binary16(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_float_binary32(_name, _attr...)     _side_field(_name, side_type_float_binary32(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_float_binary64(_name, _attr...)     _side_field(_name, side_type_float_binary64(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_float_binary128(_name, _attr...)    _side_field(_name, side_type_float_binary128(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_string(_name, _attr...)             _side_field(_name, side_type_string(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_string16(_name, _attr...)           _side_field(_name, side_type_string16(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_string32(_name, _attr...)           _side_field(_name, side_type_string32(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 #define side_field_dynamic(_name)                      _side_field(_name, side_type_dynamic())
 
 /* Little endian */
-#define side_type_u16_le(_attr)                                _side_type_integer(SIDE_TYPE_U16, false, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint16_t), 0, SIDE_PARAM(_attr))
-#define side_type_u32_le(_attr)                                _side_type_integer(SIDE_TYPE_U32, false, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint32_t), 0, SIDE_PARAM(_attr))
-#define side_type_u64_le(_attr)                                _side_type_integer(SIDE_TYPE_U64, false, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint64_t), 0, SIDE_PARAM(_attr))
-#define side_type_s16_le(_attr)                                _side_type_integer(SIDE_TYPE_S16, true, SIDE_TYPE_BYTE_ORDER_LE, sizeof(int16_t), 0, SIDE_PARAM(_attr))
-#define side_type_s32_le(_attr)                                _side_type_integer(SIDE_TYPE_S32, true, SIDE_TYPE_BYTE_ORDER_LE, sizeof(int32_t), 0, SIDE_PARAM(_attr))
-#define side_type_s64_le(_attr)                                _side_type_integer(SIDE_TYPE_S64, true, SIDE_TYPE_BYTE_ORDER_LE, sizeof(int64_t), 0, SIDE_PARAM(_attr))
-#define side_type_pointer_le(_attr)                    _side_type_integer(SIDE_TYPE_POINTER, false, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uintptr_t), 0, SIDE_PARAM(_attr))
-#define side_type_float_binary16_le(_attr)             _side_type_float(SIDE_TYPE_FLOAT_BINARY16, SIDE_TYPE_BYTE_ORDER_LE, sizeof(_Float16), SIDE_PARAM(_attr))
-#define side_type_float_binary32_le(_attr)             _side_type_float(SIDE_TYPE_FLOAT_BINARY32, SIDE_TYPE_BYTE_ORDER_LE, sizeof(_Float32), SIDE_PARAM(_attr))
-#define side_type_float_binary64_le(_attr)             _side_type_float(SIDE_TYPE_FLOAT_BINARY64, SIDE_TYPE_BYTE_ORDER_LE, sizeof(_Float64), SIDE_PARAM(_attr))
-#define side_type_float_binary128_le(_attr)            _side_type_float(SIDE_TYPE_FLOAT_BINARY128, SIDE_TYPE_BYTE_ORDER_LE, sizeof(_Float128), SIDE_PARAM(_attr))
-#define side_type_string16_le(_attr)                   _side_type_string(SIDE_TYPE_STRING_UTF16, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint16_t), SIDE_PARAM(_attr))
-#define side_type_string32_le(_attr)                   _side_type_string(SIDE_TYPE_STRING_UTF32, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint32_t), SIDE_PARAM(_attr))
-
-#define side_field_u16_le(_name, _attr)                        _side_field(_name, side_type_u16_le(SIDE_PARAM(_attr)))
-#define side_field_u32_le(_name, _attr)                        _side_field(_name, side_type_u32_le(SIDE_PARAM(_attr)))
-#define side_field_u64_le(_name, _attr)                        _side_field(_name, side_type_u64_le(SIDE_PARAM(_attr)))
-#define side_field_s16_le(_name, _attr)                        _side_field(_name, side_type_s16_le(SIDE_PARAM(_attr)))
-#define side_field_s32_le(_name, _attr)                        _side_field(_name, side_type_s32_le(SIDE_PARAM(_attr)))
-#define side_field_s64_le(_name, _attr)                        _side_field(_name, side_type_s64_le(SIDE_PARAM(_attr)))
-#define side_field_pointer_le(_name, _attr)            _side_field(_name, side_type_pointer_le(SIDE_PARAM(_attr)))
-#define side_field_float_binary16_le(_name, _attr)     _side_field(_name, side_type_float_binary16_le(SIDE_PARAM(_attr)))
-#define side_field_float_binary32_le(_name, _attr)     _side_field(_name, side_type_float_binary32_le(SIDE_PARAM(_attr)))
-#define side_field_float_binary64_le(_name, _attr)     _side_field(_name, side_type_float_binary64_le(SIDE_PARAM(_attr)))
-#define side_field_float_binary128_le(_name, _attr)    _side_field(_name, side_type_float_binary128_le(SIDE_PARAM(_attr)))
-#define side_field_string16_le(_name, _attr)           _side_field(_name, side_type_string16_le(SIDE_PARAM(_attr)))
-#define side_field_string32_le(_name, _attr)           _side_field(_name, side_type_string32_le(SIDE_PARAM(_attr)))
+#define side_type_u16_le(_attr...)                     _side_type_integer(SIDE_TYPE_U16, false, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint16_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_u32_le(_attr...)                     _side_type_integer(SIDE_TYPE_U32, false, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint32_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_u64_le(_attr...)                     _side_type_integer(SIDE_TYPE_U64, false, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint64_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_s16_le(_attr...)                     _side_type_integer(SIDE_TYPE_S16, true, SIDE_TYPE_BYTE_ORDER_LE, sizeof(int16_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_s32_le(_attr...)                     _side_type_integer(SIDE_TYPE_S32, true, SIDE_TYPE_BYTE_ORDER_LE, sizeof(int32_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_s64_le(_attr...)                     _side_type_integer(SIDE_TYPE_S64, true, SIDE_TYPE_BYTE_ORDER_LE, sizeof(int64_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_pointer_le(_attr...)                 _side_type_integer(SIDE_TYPE_POINTER, false, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uintptr_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_float_binary16_le(_attr...)          _side_type_float(SIDE_TYPE_FLOAT_BINARY16, SIDE_TYPE_BYTE_ORDER_LE, sizeof(_Float16), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_float_binary32_le(_attr...)          _side_type_float(SIDE_TYPE_FLOAT_BINARY32, SIDE_TYPE_BYTE_ORDER_LE, sizeof(_Float32), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_float_binary64_le(_attr...)          _side_type_float(SIDE_TYPE_FLOAT_BINARY64, SIDE_TYPE_BYTE_ORDER_LE, sizeof(_Float64), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_float_binary128_le(_attr...)         _side_type_float(SIDE_TYPE_FLOAT_BINARY128, SIDE_TYPE_BYTE_ORDER_LE, sizeof(_Float128), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_string16_le(_attr...)                _side_type_string(SIDE_TYPE_STRING_UTF16, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint16_t), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_string32_le(_attr...)                        _side_type_string(SIDE_TYPE_STRING_UTF32, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint32_t), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+
+#define side_field_u16_le(_name, _attr...)             _side_field(_name, side_type_u16_le(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_u32_le(_name, _attr...)             _side_field(_name, side_type_u32_le(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_u64_le(_name, _attr...)             _side_field(_name, side_type_u64_le(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_s16_le(_name, _attr...)             _side_field(_name, side_type_s16_le(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_s32_le(_name, _attr...)             _side_field(_name, side_type_s32_le(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_s64_le(_name, _attr...)             _side_field(_name, side_type_s64_le(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_pointer_le(_name, _attr...)         _side_field(_name, side_type_pointer_le(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_float_binary16_le(_name, _attr...)  _side_field(_name, side_type_float_binary16_le(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_float_binary32_le(_name, _attr...)  _side_field(_name, side_type_float_binary32_le(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_float_binary64_le(_name, _attr...)  _side_field(_name, side_type_float_binary64_le(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_float_binary128_le(_name, _attr...) _side_field(_name, side_type_float_binary128_le(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_string16_le(_name, _attr...)                _side_field(_name, side_type_string16_le(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_string32_le(_name, _attr...)                _side_field(_name, side_type_string32_le(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 
 /* Big endian */
-#define side_type_u16_be(_attr)                                _side_type_integer(SIDE_TYPE_U16, false, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint16_t), 0, SIDE_PARAM(_attr))
-#define side_type_u32_be(_attr)                                _side_type_integer(SIDE_TYPE_U32, false, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint32_t), 0, SIDE_PARAM(_attr))
-#define side_type_u64_be(_attr)                                _side_type_integer(SIDE_TYPE_U64, false, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint64_t), 0, SIDE_PARAM(_attr))
-#define side_type_s16_be(_attr)                                _side_type_integer(SIDE_TYPE_S16, false, SIDE_TYPE_BYTE_ORDER_BE, sizeof(int16_t), 0, SIDE_PARAM(_attr))
-#define side_type_s32_be(_attr)                                _side_type_integer(SIDE_TYPE_S32, false, SIDE_TYPE_BYTE_ORDER_BE, sizeof(int32_t), 0, SIDE_PARAM(_attr))
-#define side_type_s64_be(_attr)                                _side_type_integer(SIDE_TYPE_S64, false, SIDE_TYPE_BYTE_ORDER_BE, sizeof(int64_t), 0, SIDE_PARAM(_attr))
-#define side_type_pointer_be(_attr)                    _side_type_integer(SIDE_TYPE_POINTER, false, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uintptr_t), 0, SIDE_PARAM(_attr))
-#define side_type_float_binary16_be(_attr)             _side_type_float(SIDE_TYPE_FLOAT_BINARY16, SIDE_TYPE_BYTE_ORDER_BE, sizeof(_Float16), SIDE_PARAM(_attr))
-#define side_type_float_binary32_be(_attr)             _side_type_float(SIDE_TYPE_FLOAT_BINARY32, SIDE_TYPE_BYTE_ORDER_BE, sizeof(_Float32), SIDE_PARAM(_attr))
-#define side_type_float_binary64_be(_attr)             _side_type_float(SIDE_TYPE_FLOAT_BINARY64, SIDE_TYPE_BYTE_ORDER_BE, sizeof(_Float64), SIDE_PARAM(_attr))
-#define side_type_float_binary128_be(_attr)            _side_type_float(SIDE_TYPE_FLOAT_BINARY128, SIDE_TYPE_BYTE_ORDER_BE, sizeof(_Float128), SIDE_PARAM(_attr))
-#define side_type_string16_be(_attr)                   _side_type_string(SIDE_TYPE_STRING_UTF16, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint16_t), SIDE_PARAM(_attr))
-#define side_type_string32_be(_attr)                   _side_type_string(SIDE_TYPE_STRING_UTF32, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint32_t), SIDE_PARAM(_attr))
-
-#define side_field_u16_be(_name, _attr)                        _side_field(_name, side_type_u16_be(SIDE_PARAM(_attr)))
-#define side_field_u32_be(_name, _attr)                        _side_field(_name, side_type_u32_be(SIDE_PARAM(_attr)))
-#define side_field_u64_be(_name, _attr)                        _side_field(_name, side_type_u64_be(SIDE_PARAM(_attr)))
-#define side_field_s16_be(_name, _attr)                        _side_field(_name, side_type_s16_be(SIDE_PARAM(_attr)))
-#define side_field_s32_be(_name, _attr)                        _side_field(_name, side_type_s32_be(SIDE_PARAM(_attr)))
-#define side_field_s64_be(_name, _attr)                        _side_field(_name, side_type_s64_be(SIDE_PARAM(_attr)))
-#define side_field_pointer_be(_name, _attr)            _side_field(_name, side_type_pointer_be(SIDE_PARAM(_attr)))
-#define side_field_float_binary16_be(_name, _attr)     _side_field(_name, side_type_float_binary16_be(SIDE_PARAM(_attr)))
-#define side_field_float_binary32_be(_name, _attr)     _side_field(_name, side_type_float_binary32_be(SIDE_PARAM(_attr)))
-#define side_field_float_binary64_be(_name, _attr)     _side_field(_name, side_type_float_binary64_be(SIDE_PARAM(_attr)))
-#define side_field_float_binary128_be(_name, _attr)    _side_field(_name, side_type_float_binary128_be(SIDE_PARAM(_attr)))
-#define side_field_string16_be(_name, _attr)           _side_field(_name, side_type_string16_be(SIDE_PARAM(_attr)))
-#define side_field_string32_be(_name, _attr)           _side_field(_name, side_type_string32_be(SIDE_PARAM(_attr)))
+#define side_type_u16_be(_attr...)                     _side_type_integer(SIDE_TYPE_U16, false, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint16_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_u32_be(_attr...)                     _side_type_integer(SIDE_TYPE_U32, false, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint32_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_u64_be(_attr...)                     _side_type_integer(SIDE_TYPE_U64, false, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint64_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_s16_be(_attr...)                     _side_type_integer(SIDE_TYPE_S16, false, SIDE_TYPE_BYTE_ORDER_BE, sizeof(int16_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_s32_be(_attr...)                     _side_type_integer(SIDE_TYPE_S32, false, SIDE_TYPE_BYTE_ORDER_BE, sizeof(int32_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_s64_be(_attr...)                     _side_type_integer(SIDE_TYPE_S64, false, SIDE_TYPE_BYTE_ORDER_BE, sizeof(int64_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_pointer_be(_attr...)                 _side_type_integer(SIDE_TYPE_POINTER, false, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uintptr_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_float_binary16_be(_attr...)          _side_type_float(SIDE_TYPE_FLOAT_BINARY16, SIDE_TYPE_BYTE_ORDER_BE, sizeof(_Float16), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_float_binary32_be(_attr...)          _side_type_float(SIDE_TYPE_FLOAT_BINARY32, SIDE_TYPE_BYTE_ORDER_BE, sizeof(_Float32), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_float_binary64_be(_attr...)          _side_type_float(SIDE_TYPE_FLOAT_BINARY64, SIDE_TYPE_BYTE_ORDER_BE, sizeof(_Float64), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_float_binary128_be(_attr...)         _side_type_float(SIDE_TYPE_FLOAT_BINARY128, SIDE_TYPE_BYTE_ORDER_BE, sizeof(_Float128), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_string16_be(_attr...)                _side_type_string(SIDE_TYPE_STRING_UTF16, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint16_t), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_string32_be(_attr...)                        _side_type_string(SIDE_TYPE_STRING_UTF32, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint32_t), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+
+#define side_field_u16_be(_name, _attr...)             _side_field(_name, side_type_u16_be(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_u32_be(_name, _attr...)             _side_field(_name, side_type_u32_be(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_u64_be(_name, _attr...)             _side_field(_name, side_type_u64_be(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_s16_be(_name, _attr...)             _side_field(_name, side_type_s16_be(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_s32_be(_name, _attr...)             _side_field(_name, side_type_s32_be(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_s64_be(_name, _attr...)             _side_field(_name, side_type_s64_be(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_pointer_be(_name, _attr...)         _side_field(_name, side_type_pointer_be(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_float_binary16_be(_name, _attr...)  _side_field(_name, side_type_float_binary16_be(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_float_binary32_be(_name, _attr...)  _side_field(_name, side_type_float_binary32_be(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_float_binary64_be(_name, _attr...)  _side_field(_name, side_type_float_binary64_be(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_float_binary128_be(_name, _attr...) _side_field(_name, side_type_float_binary128_be(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_string16_be(_name, _attr...)                _side_field(_name, side_type_string16_be(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_string32_be(_name, _attr...)                _side_field(_name, side_type_string32_be(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 
 #define side_type_enum(_mappings, _elem_type) \
        { \
@@ -986,60 +1020,87 @@ struct side_event_description {
                .nr_attr  = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
        }
 
-#define side_define_struct(_identifier, _fields, _attr) \
-       const struct side_type_struct _identifier = _side_type_struct_define(SIDE_PARAM(_fields), SIDE_PARAM(_attr))
+#define side_define_struct(_identifier, _fields, _attr...) \
+       const struct side_type_struct _identifier = _side_type_struct_define(SIDE_PARAM(_fields), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
-#define side_struct_literal(_fields, _attr) \
+#define side_struct_literal(_fields, _attr...) \
        SIDE_COMPOUND_LITERAL(const struct side_type_struct, \
-               _side_type_struct_define(SIDE_PARAM(_fields), SIDE_PARAM(_attr)))
+               _side_type_struct_define(SIDE_PARAM(_fields), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+
+#define side_type_variant(_variant) \
+       { \
+               .type = SIDE_TYPE_VARIANT, \
+               .u = { \
+                       .side_variant = _variant, \
+               }, \
+       }
+#define side_field_variant(_name, _variant) \
+       _side_field(_name, side_type_variant(SIDE_PARAM(_variant)))
+
+#define _side_type_variant_define(_selector, _options, _attr) \
+       { \
+               .selector = _selector, \
+               .options = _options, \
+               .attr = _attr, \
+               .nr_options = SIDE_ARRAY_SIZE(SIDE_PARAM(_options)), \
+               .nr_attr  = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+       }
+
+#define side_define_variant(_identifier, _selector, _options, _attr...) \
+       const struct side_type_variant _identifier = \
+               _side_type_variant_define(SIDE_PARAM(_selector), SIDE_PARAM(_options), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
-#define side_type_array(_elem_type, _length, _attr) \
+#define side_variant_literal(_selector, _options, _attr...) \
+       SIDE_COMPOUND_LITERAL(const struct side_type_variant, \
+               _side_type_variant_define(SIDE_PARAM(_selector), SIDE_PARAM(_options), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+
+#define side_type_array(_elem_type, _length, _attr...) \
        { \
                .type = SIDE_TYPE_ARRAY, \
                .u = { \
                        .side_array = { \
                                .elem_type = _elem_type, \
-                               .attr = _attr, \
+                               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
                                .length = _length, \
-                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                        }, \
                }, \
        }
-#define side_field_array(_name, _elem_type, _length, _attr) \
-       _side_field(_name, side_type_array(SIDE_PARAM(_elem_type), _length, SIDE_PARAM(_attr)))
+#define side_field_array(_name, _elem_type, _length, _attr...) \
+       _side_field(_name, side_type_array(SIDE_PARAM(_elem_type), _length, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 
-#define side_type_vla(_elem_type, _attr) \
+#define side_type_vla(_elem_type, _attr...) \
        { \
                .type = SIDE_TYPE_VLA, \
                .u = { \
                        .side_vla = { \
                                .elem_type = _elem_type, \
-                               .attr = _attr, \
-                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                        }, \
                }, \
        }
-#define side_field_vla(_name, _elem_type, _attr) \
-       _side_field(_name, side_type_vla(SIDE_PARAM(_elem_type), SIDE_PARAM(_attr)))
+#define side_field_vla(_name, _elem_type, _attr...) \
+       _side_field(_name, side_type_vla(SIDE_PARAM(_elem_type), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 
-#define side_type_vla_visitor(_elem_type, _visitor, _attr) \
+#define side_type_vla_visitor(_elem_type, _visitor, _attr...) \
        { \
                .type = SIDE_TYPE_VLA_VISITOR, \
                .u = { \
                        .side_vla_visitor = { \
                                .elem_type = SIDE_PARAM(_elem_type), \
                                .visitor = _visitor, \
-                               .attr = _attr, \
-                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                        }, \
                }, \
        }
-#define side_field_vla_visitor(_name, _elem_type, _visitor, _attr) \
-       _side_field(_name, side_type_vla_visitor(SIDE_PARAM(_elem_type), _visitor, SIDE_PARAM(_attr)))
+#define side_field_vla_visitor(_name, _elem_type, _visitor, _attr...) \
+       _side_field(_name, side_type_vla_visitor(SIDE_PARAM(_elem_type), _visitor, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 
 /* Gather field and type definitions */
 
-#define side_type_gather_byte(_offset, _access_mode, _attr) \
+#define side_type_gather_byte(_offset, _access_mode, _attr...) \
        { \
                .type = SIDE_TYPE_GATHER_BYTE, \
                .u = { \
@@ -1049,18 +1110,18 @@ struct side_event_description {
                                                .offset = _offset, \
                                                .access_mode = _access_mode, \
                                                .type = { \
-                                                       .attr = _attr, \
-                                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                                                       .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                                }, \
                                        }, \
                                }, \
                        }, \
                }, \
        }
-#define side_field_gather_byte(_name, _offset, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_byte(_offset, _access_mode, SIDE_PARAM(_attr)))
+#define side_field_gather_byte(_name, _offset, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_byte(_offset, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 
-#define _side_type_gather_bool(_byte_order, _offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr) \
+#define _side_type_gather_bool(_byte_order, _offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr...) \
        { \
                .type = SIDE_TYPE_GATHER_BOOL, \
                .u = { \
@@ -1070,8 +1131,8 @@ struct side_event_description {
                                                .offset = _offset, \
                                                .access_mode = _access_mode, \
                                                .type = { \
-                                                       .attr = _attr, \
-                                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                                                       .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                                        .bool_size = _bool_size, \
                                                        .len_bits = _len_bits, \
                                                        .byte_order = _byte_order, \
@@ -1082,22 +1143,22 @@ struct side_event_description {
                        }, \
                }, \
        }
-#define side_type_gather_bool(_offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr) \
-       _side_type_gather_bool(SIDE_TYPE_BYTE_ORDER_HOST, _offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr)
-#define side_type_gather_bool_le(_offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr) \
-       _side_type_gather_bool(SIDE_TYPE_BYTE_ORDER_LE, _offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr)
-#define side_type_gather_bool_be(_offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr) \
-       _side_type_gather_bool(SIDE_TYPE_BYTE_ORDER_BE, _offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr)
-
-#define side_field_gather_bool(_name, _offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_bool(_offset, _bool_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(_attr)))
-#define side_field_gather_bool_le(_name, _offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_bool_le(_offset, _bool_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(_attr)))
-#define side_field_gather_bool_be(_name, _offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_bool_be(_offset, _bool_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(_attr)))
+#define side_type_gather_bool(_offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr...) \
+       _side_type_gather_bool(SIDE_TYPE_BYTE_ORDER_HOST, _offset, _bool_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_gather_bool_le(_offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr...) \
+       _side_type_gather_bool(SIDE_TYPE_BYTE_ORDER_LE, _offset, _bool_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_gather_bool_be(_offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr...) \
+       _side_type_gather_bool(SIDE_TYPE_BYTE_ORDER_BE, _offset, _bool_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+
+#define side_field_gather_bool(_name, _offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_bool(_offset, _bool_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))))
+#define side_field_gather_bool_le(_name, _offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_bool_le(_offset, _bool_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))))
+#define side_field_gather_bool_be(_name, _offset, _bool_size, _offset_bits, _len_bits, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_bool_be(_offset, _bool_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))))
 
 #define _side_type_gather_integer(_type, _signedness, _byte_order, _offset, \
-               _integer_size, _offset_bits, _len_bits, _access_mode, _attr) \
+               _integer_size, _offset_bits, _len_bits, _access_mode, _attr...) \
        { \
                .type = _type, \
                .u = { \
@@ -1107,8 +1168,8 @@ struct side_event_description {
                                                .offset = _offset, \
                                                .access_mode = _access_mode, \
                                                .type = { \
-                                                       .attr = _attr, \
-                                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                                                       .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                                        .integer_size = _integer_size, \
                                                        .len_bits = _len_bits, \
                                                        .signedness = _signedness, \
@@ -1121,61 +1182,61 @@ struct side_event_description {
                }, \
        }
 
-#define side_type_gather_unsigned_integer(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr) \
+#define side_type_gather_unsigned_integer(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr...) \
        _side_type_gather_integer(SIDE_TYPE_GATHER_INTEGER, false,  SIDE_TYPE_BYTE_ORDER_HOST, \
-                       _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(_attr))
-#define side_type_gather_signed_integer(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr) \
+                       _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_gather_signed_integer(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr...) \
        _side_type_gather_integer(SIDE_TYPE_GATHER_INTEGER, true, SIDE_TYPE_BYTE_ORDER_HOST, \
-                       _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(_attr))
+                       _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
-#define side_type_gather_unsigned_integer_le(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr) \
+#define side_type_gather_unsigned_integer_le(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr...) \
        _side_type_gather_integer(SIDE_TYPE_GATHER_INTEGER, false,  SIDE_TYPE_BYTE_ORDER_LE, \
-                       _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(_attr))
-#define side_type_gather_signed_integer_le(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr) \
+                       _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_gather_signed_integer_le(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr...) \
        _side_type_gather_integer(SIDE_TYPE_GATHER_INTEGER, true, SIDE_TYPE_BYTE_ORDER_LE, \
-                       _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(_attr))
+                       _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
-#define side_type_gather_unsigned_integer_be(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr) \
+#define side_type_gather_unsigned_integer_be(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr...) \
        _side_type_gather_integer(SIDE_TYPE_GATHER_INTEGER, false,  SIDE_TYPE_BYTE_ORDER_BE, \
-                       _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(_attr))
-#define side_type_gather_signed_integer_be(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr) \
+                       _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_gather_signed_integer_be(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr...) \
        _side_type_gather_integer(SIDE_TYPE_GATHER_INTEGER, true, SIDE_TYPE_BYTE_ORDER_BE, \
-                       _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(_attr))
+                       _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
-#define side_field_gather_unsigned_integer(_name, _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_unsigned_integer(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(_attr)))
-#define side_field_gather_signed_integer(_name, _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_signed_integer(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(_attr)))
+#define side_field_gather_unsigned_integer(_name, _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_unsigned_integer(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_gather_signed_integer(_name, _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_signed_integer(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 
-#define side_field_gather_unsigned_integer_le(_name, _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_unsigned_integer_le(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(_attr)))
-#define side_field_gather_signed_integer_le(_name, _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_signed_integer_le(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(_attr)))
+#define side_field_gather_unsigned_integer_le(_name, _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_unsigned_integer_le(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_gather_signed_integer_le(_name, _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_signed_integer_le(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 
-#define side_field_gather_unsigned_integer_be(_name, _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_unsigned_integer_be(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(_attr)))
-#define side_field_gather_signed_integer_be(_name, _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_signed_integer_be(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM(_attr)))
+#define side_field_gather_unsigned_integer_be(_name, _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_unsigned_integer_be(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_gather_signed_integer_be(_name, _integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_signed_integer_be(_integer_offset, _integer_size, _offset_bits, _len_bits, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 
-#define side_type_gather_pointer(_offset, _access_mode, _attr) \
+#define side_type_gather_pointer(_offset, _access_mode, _attr...) \
        _side_type_gather_integer(SIDE_TYPE_GATHER_POINTER, false, SIDE_TYPE_BYTE_ORDER_HOST, \
-                       _offset, sizeof(uintptr_t), 0, 0, _access_mode, SIDE_PARAM(_attr))
-#define side_field_gather_pointer(_name, _offset, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_pointer(_offset, _access_mode, SIDE_PARAM(_attr)))
+                       _offset, sizeof(uintptr_t), 0, 0, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_field_gather_pointer(_name, _offset, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_pointer(_offset, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 
-#define side_type_gather_pointer_le(_offset, _access_mode, _attr) \
+#define side_type_gather_pointer_le(_offset, _access_mode, _attr...) \
        _side_type_gather_integer(SIDE_TYPE_GATHER_POINTER, false, SIDE_TYPE_BYTE_ORDER_LE, \
-                       _offset, sizeof(uintptr_t), 0, 0, _access_mode, SIDE_PARAM(_attr))
-#define side_field_gather_pointer_le(_name, _offset, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_pointer_le(_offset, _access_mode, SIDE_PARAM(_attr)))
+                       _offset, sizeof(uintptr_t), 0, 0, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_field_gather_pointer_le(_name, _offset, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_pointer_le(_offset, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 
-#define side_type_gather_pointer_be(_offset, _access_mode, _attr) \
+#define side_type_gather_pointer_be(_offset, _access_mode, _attr...) \
        _side_type_gather_integer(SIDE_TYPE_GATHER_POINTER, false, SIDE_TYPE_BYTE_ORDER_BE, \
-                       _offset, sizeof(uintptr_t), 0, 0, _access_mode, SIDE_PARAM(_attr))
-#define side_field_gather_pointer_be(_name, _offset, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_pointer_be(_offset, _access_mode, SIDE_PARAM(_attr)))
+                       _offset, sizeof(uintptr_t), 0, 0, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_field_gather_pointer_be(_name, _offset, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_pointer_be(_offset, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 
-#define _side_type_gather_float(_byte_order, _offset, _float_size, _access_mode, _attr) \
+#define _side_type_gather_float(_byte_order, _offset, _float_size, _access_mode, _attr...) \
        { \
                .type = SIDE_TYPE_GATHER_FLOAT, \
                .u = { \
@@ -1185,8 +1246,8 @@ struct side_event_description {
                                                .offset = _offset, \
                                                .access_mode = _access_mode, \
                                                .type = { \
-                                                       .attr = _attr, \
-                                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                                                       .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                                        .float_size = _float_size, \
                                                        .byte_order = _byte_order, \
                                                }, \
@@ -1196,21 +1257,21 @@ struct side_event_description {
                }, \
        }
 
-#define side_type_gather_float(_offset, _float_size, _access_mode, _attr) \
-       _side_type_gather_float(SIDE_TYPE_FLOAT_WORD_ORDER_HOST, _offset, _float_size, _access_mode, _attr)
-#define side_type_gather_float_le(_offset, _float_size, _access_mode, _attr) \
-       _side_type_gather_float(SIDE_TYPE_BYTE_ORDER_LE, _offset, _float_size, _access_mode, _attr)
-#define side_type_gather_float_be(_offset, _float_size, _access_mode, _attr) \
-       _side_type_gather_float(SIDE_TYPE_BYTE_ORDER_BE, _offset, _float_size, _access_mode, _attr)
-
-#define side_field_gather_float(_name, _offset, _float_size, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_float(_offset, _float_size, _access_mode, _attr))
-#define side_field_gather_float_le(_name, _offset, _float_size, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_float_le(_offset, _float_size, _access_mode, _attr))
-#define side_field_gather_float_be(_name, _offset, _float_size, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_float_be(_offset, _float_size, _access_mode, _attr))
-
-#define _side_type_gather_string(_offset, _byte_order, _unit_size, _access_mode, _attr) \
+#define side_type_gather_float(_offset, _float_size, _access_mode, _attr...) \
+       _side_type_gather_float(SIDE_TYPE_FLOAT_WORD_ORDER_HOST, _offset, _float_size, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_gather_float_le(_offset, _float_size, _access_mode, _attr...) \
+       _side_type_gather_float(SIDE_TYPE_BYTE_ORDER_LE, _offset, _float_size, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_gather_float_be(_offset, _float_size, _access_mode, _attr...) \
+       _side_type_gather_float(SIDE_TYPE_BYTE_ORDER_BE, _offset, _float_size, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+
+#define side_field_gather_float(_name, _offset, _float_size, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_float(_offset, _float_size, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_gather_float_le(_name, _offset, _float_size, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_float_le(_offset, _float_size, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_gather_float_be(_name, _offset, _float_size, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_float_be(_offset, _float_size, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+
+#define _side_type_gather_string(_offset, _byte_order, _unit_size, _access_mode, _attr...) \
        { \
                .type = SIDE_TYPE_GATHER_STRING, \
                .u = { \
@@ -1220,8 +1281,8 @@ struct side_event_description {
                                                .offset = _offset, \
                                                .access_mode = _access_mode, \
                                                .type = { \
-                                                       .attr = _attr, \
-                                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                                                       .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                                        .unit_size = _unit_size, \
                                                        .byte_order = _byte_order, \
                                                }, \
@@ -1230,38 +1291,38 @@ struct side_event_description {
                        }, \
                }, \
        }
-#define side_type_gather_string(_offset, _access_mode, _attr) \
-       _side_type_gather_string(_offset, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint8_t), _access_mode, SIDE_PARAM(_attr))
-#define side_field_gather_string(_name, _offset, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_string(_offset, _access_mode, SIDE_PARAM(_attr)))
-
-#define side_type_gather_string16(_offset, _access_mode, _attr) \
-       _side_type_gather_string(_offset, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint16_t), _access_mode, SIDE_PARAM(_attr))
-#define side_type_gather_string16_le(_offset, _access_mode, _attr) \
-       _side_type_gather_string(_offset, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint16_t), _access_mode, SIDE_PARAM(_attr))
-#define side_type_gather_string16_be(_offset, _access_mode, _attr) \
-       _side_type_gather_string(_offset, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint16_t), _access_mode, SIDE_PARAM(_attr))
-
-#define side_field_gather_string16(_name, _offset, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_string16(_offset, _access_mode, SIDE_PARAM(_attr)))
-#define side_field_gather_string16_le(_name, _offset, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_string16_le(_offset, _access_mode, SIDE_PARAM(_attr)))
-#define side_field_gather_string16_be(_name, _offset, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_string16_be(_offset, _access_mode, SIDE_PARAM(_attr)))
-
-#define side_type_gather_string32(_offset, _access_mode, _attr) \
-       _side_type_gather_string(_offset, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint32_t), _access_mode, SIDE_PARAM(_attr))
-#define side_type_gather_string32_le(_offset, _access_mode, _attr) \
-       _side_type_gather_string(_offset, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint32_t), _access_mode, SIDE_PARAM(_attr))
-#define side_type_gather_string32_be(_offset, _access_mode, _attr) \
-       _side_type_gather_string(_offset, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint32_t), _access_mode, SIDE_PARAM(_attr))
-
-#define side_field_gather_string32(_name, _offset, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_string32(_offset, _access_mode, SIDE_PARAM(_attr)))
-#define side_field_gather_string32_le(_name, _offset, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_string32_le(_offset, _access_mode, SIDE_PARAM(_attr)))
-#define side_field_gather_string32_be(_name, _offset, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_string32_be(_offset, _access_mode, SIDE_PARAM(_attr)))
+#define side_type_gather_string(_offset, _access_mode, _attr...) \
+       _side_type_gather_string(_offset, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint8_t), _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_field_gather_string(_name, _offset, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_string(_offset, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+
+#define side_type_gather_string16(_offset, _access_mode, _attr...) \
+       _side_type_gather_string(_offset, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint16_t), _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_gather_string16_le(_offset, _access_mode, _attr...) \
+       _side_type_gather_string(_offset, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint16_t), _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_gather_string16_be(_offset, _access_mode, _attr...) \
+       _side_type_gather_string(_offset, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint16_t), _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+
+#define side_field_gather_string16(_name, _offset, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_string16(_offset, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_gather_string16_le(_name, _offset, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_string16_le(_offset, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_gather_string16_be(_name, _offset, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_string16_be(_offset, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+
+#define side_type_gather_string32(_offset, _access_mode, _attr...) \
+       _side_type_gather_string(_offset, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint32_t), _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_gather_string32_le(_offset, _access_mode, _attr...) \
+       _side_type_gather_string(_offset, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint32_t), _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_type_gather_string32_be(_offset, _access_mode, _attr...) \
+       _side_type_gather_string(_offset, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint32_t), _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+
+#define side_field_gather_string32(_name, _offset, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_string32(_offset, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_gather_string32_le(_name, _offset, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_string32_le(_offset, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
+#define side_field_gather_string32_be(_name, _offset, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_string32_be(_offset, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 
 #define side_type_gather_enum(_mappings, _elem_type) \
        { \
@@ -1295,7 +1356,7 @@ struct side_event_description {
 #define side_field_gather_struct(_name, _struct_gather, _offset, _size, _access_mode) \
        _side_field(_name, side_type_gather_struct(SIDE_PARAM(_struct_gather), _offset, _size, _access_mode))
 
-#define side_type_gather_array(_elem_type_gather, _length, _offset, _access_mode, _attr) \
+#define side_type_gather_array(_elem_type_gather, _length, _offset, _access_mode, _attr...) \
        { \
                .type = SIDE_TYPE_GATHER_ARRAY, \
                .u = { \
@@ -1306,19 +1367,19 @@ struct side_event_description {
                                                .access_mode = _access_mode, \
                                                .type = { \
                                                        .elem_type = _elem_type_gather, \
-                                                       .attr = _attr, \
+                                                       .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
                                                        .length = _length, \
-                                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                                }, \
                                        }, \
                                }, \
                        }, \
                }, \
        }
-#define side_field_gather_array(_name, _elem_type, _length, _offset, _access_mode, _attr) \
-       _side_field(_name, side_type_gather_array(SIDE_PARAM(_elem_type), _length, _offset, _access_mode, SIDE_PARAM(_attr)))
+#define side_field_gather_array(_name, _elem_type, _length, _offset, _access_mode, _attr...) \
+       _side_field(_name, side_type_gather_array(SIDE_PARAM(_elem_type), _length, _offset, _access_mode, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 
-#define side_type_gather_vla(_elem_type_gather, _offset, _access_mode, _length_type_gather, _attr) \
+#define side_type_gather_vla(_elem_type_gather, _offset, _access_mode, _length_type_gather, _attr...) \
        { \
                .type = SIDE_TYPE_GATHER_VLA, \
                .u = { \
@@ -1330,16 +1391,16 @@ struct side_event_description {
                                                .access_mode = _access_mode, \
                                                .type = { \
                                                        .elem_type = _elem_type_gather, \
-                                                       .attr = _attr, \
-                                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                                                       .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                                }, \
                                        }, \
                                }, \
                        }, \
                }, \
        }
-#define side_field_gather_vla(_name, _elem_type_gather, _offset, _access_mode, _length_type_gather, _attr) \
-       _side_field(_name, side_type_gather_vla(SIDE_PARAM(_elem_type_gather), _offset, _access_mode, SIDE_PARAM(_length_type_gather), SIDE_PARAM(_attr)))
+#define side_field_gather_vla(_name, _elem_type_gather, _offset, _access_mode, _length_type_gather, _attr...) \
+       _side_field(_name, side_type_gather_vla(SIDE_PARAM(_elem_type_gather), _offset, _access_mode, SIDE_PARAM(_length_type_gather), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())))
 
 #define side_elem(...) \
        SIDE_COMPOUND_LITERAL(const struct side_type, __VA_ARGS__)
@@ -1350,6 +1411,9 @@ struct side_event_description {
 #define side_field_list(...) \
        SIDE_COMPOUND_LITERAL(const struct side_event_field, __VA_ARGS__)
 
+#define side_option_list(...) \
+       SIDE_COMPOUND_LITERAL(const struct side_variant_option, __VA_ARGS__)
+
 /* Stack-copy field arguments */
 
 #define side_arg_null(_val)            { .type = SIDE_TYPE_NULL }
@@ -1374,6 +1438,22 @@ struct side_event_description {
 #define side_arg_float_binary128(_val) { .type = SIDE_TYPE_FLOAT_BINARY128, .u = { .side_static = { .float_value = { .side_float_binary128 = (_val) } } } }
 
 #define side_arg_struct(_side_type)    { .type = SIDE_TYPE_STRUCT, .u = { .side_static = { .side_struct = (_side_type) } } }
+
+#define side_arg_define_variant(_identifier, _selector_val, _option) \
+       const struct side_arg_variant _identifier = { \
+               .selector = _selector_val, \
+               .option = _option, \
+       }
+#define side_arg_variant(_side_variant) \
+       { \
+               .type = SIDE_TYPE_VARIANT, \
+               .u = { \
+                       .side_static = { \
+                               .side_variant = (_side_variant), \
+                       }, \
+               }, \
+       }
+
 #define side_arg_array(_side_type)     { .type = SIDE_TYPE_ARRAY, .u = { .side_static = { .side_array = (_side_type) } } }
 #define side_arg_vla(_side_type)       { .type = SIDE_TYPE_VLA, .u = { .side_static = { .side_vla = (_side_type) } } }
 #define side_arg_vla_visitor(_ctx)     { .type = SIDE_TYPE_VLA_VISITOR, .u = { .side_static = { .side_vla_app_visitor_ctx = (_ctx) } } }
@@ -1392,28 +1472,28 @@ struct side_event_description {
 
 /* Dynamic field arguments */
 
-#define side_arg_dynamic_null(_attr) \
+#define side_arg_dynamic_null(_attr...) \
        { \
                .type = SIDE_TYPE_DYNAMIC_NULL, \
                .u = { \
                        .side_dynamic = { \
                                .side_null = { \
-                                       .attr = _attr, \
-                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                                       .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                }, \
                        }, \
                }, \
        }
 
-#define side_arg_dynamic_bool(_val, _attr) \
+#define side_arg_dynamic_bool(_val, _attr...) \
        { \
                .type = SIDE_TYPE_DYNAMIC_BOOL, \
                .u = { \
                        .side_dynamic = { \
                                .side_bool = { \
                                        .type = { \
-                                               .attr = _attr, \
-                                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                                               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                                .bool_size = sizeof(uint8_t), \
                                                .len_bits = 0, \
                                                .byte_order = SIDE_TYPE_BYTE_ORDER_HOST, \
@@ -1426,30 +1506,31 @@ struct side_event_description {
                }, \
        }
 
-#define side_arg_dynamic_byte(_val, _attr) \
+#define side_arg_dynamic_byte(_val, _attr...) \
        { \
                .type = SIDE_TYPE_DYNAMIC_BYTE, \
                .u = { \
                        .side_dynamic = { \
                                .side_byte = { \
                                        .type = { \
-                                               .attr = _attr, \
-                                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                                               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                        }, \
                                        .value = (_val), \
                                }, \
                        }, \
                }, \
        }
-#define _side_arg_dynamic_string(_val, _byte_order, _unit_size, _attr) \
+
+#define _side_arg_dynamic_string(_val, _byte_order, _unit_size, _attr...) \
        { \
                .type = SIDE_TYPE_DYNAMIC_STRING, \
                .u = { \
                        .side_dynamic = { \
                                .side_string = { \
                                        .type = { \
-                                               .attr = _attr, \
-                                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                                               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                                .unit_size = _unit_size, \
                                                .byte_order = _byte_order, \
                                        }, \
@@ -1458,30 +1539,30 @@ struct side_event_description {
                        }, \
                }, \
        }
-#define side_arg_dynamic_string(_val, _attr) \
-       _side_arg_dynamic_string(_val, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint8_t), SIDE_PARAM(_attr))
-#define side_arg_dynamic_string16(_val, _attr) \
-       _side_arg_dynamic_string(_val, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint16_t), SIDE_PARAM(_attr))
-#define side_arg_dynamic_string16_le(_val, _attr) \
-       _side_arg_dynamic_string(_val, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint16_t), SIDE_PARAM(_attr))
-#define side_arg_dynamic_string16_be(_val, _attr) \
-       _side_arg_dynamic_string(_val, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint16_t), SIDE_PARAM(_attr))
-#define side_arg_dynamic_string32(_val, _attr) \
-       _side_arg_dynamic_string(_val, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint32_t), SIDE_PARAM(_attr))
-#define side_arg_dynamic_string32_le(_val, _attr) \
-       _side_arg_dynamic_string(_val, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint32_t), SIDE_PARAM(_attr))
-#define side_arg_dynamic_string32_be(_val, _attr) \
-       _side_arg_dynamic_string(_val, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint32_t), SIDE_PARAM(_attr))
-
-#define _side_arg_dynamic_integer(_field, _val, _type, _signedness, _byte_order, _integer_size, _len_bits, _attr) \
+#define side_arg_dynamic_string(_val, _attr...) \
+       _side_arg_dynamic_string(_val, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint8_t), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_string16(_val, _attr...) \
+       _side_arg_dynamic_string(_val, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint16_t), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_string16_le(_val, _attr...) \
+       _side_arg_dynamic_string(_val, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint16_t), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_string16_be(_val, _attr...) \
+       _side_arg_dynamic_string(_val, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint16_t), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_string32(_val, _attr...) \
+       _side_arg_dynamic_string(_val, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint32_t), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_string32_le(_val, _attr...) \
+       _side_arg_dynamic_string(_val, SIDE_TYPE_BYTE_ORDER_LE, sizeof(uint32_t), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_string32_be(_val, _attr...) \
+       _side_arg_dynamic_string(_val, SIDE_TYPE_BYTE_ORDER_BE, sizeof(uint32_t), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+
+#define _side_arg_dynamic_integer(_field, _val, _type, _signedness, _byte_order, _integer_size, _len_bits, _attr...) \
        { \
                .type = _type, \
                .u = { \
                        .side_dynamic = { \
                                .side_integer = { \
                                        .type = { \
-                                               .attr = _attr, \
-                                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                                               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                                .integer_size = _integer_size, \
                                                .len_bits = _len_bits, \
                                                .signedness = _signedness, \
@@ -1495,38 +1576,38 @@ struct side_event_description {
                }, \
        }
 
-#define side_arg_dynamic_u8(_val, _attr) \
-       _side_arg_dynamic_integer(.side_u8, _val, SIDE_TYPE_DYNAMIC_INTEGER, false, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint8_t), 0, SIDE_PARAM(_attr))
-#define side_arg_dynamic_s8(_val, _attr) \
-       _side_arg_dynamic_integer(.side_s8, _val, SIDE_TYPE_DYNAMIC_INTEGER, true, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(int8_t), 0, SIDE_PARAM(_attr))
-
-#define _side_arg_dynamic_u16(_val, _byte_order, _attr) \
-       _side_arg_dynamic_integer(.side_u16, _val, SIDE_TYPE_DYNAMIC_INTEGER, false, _byte_order, sizeof(uint16_t), 0, SIDE_PARAM(_attr))
-#define _side_arg_dynamic_u32(_val, _byte_order, _attr) \
-       _side_arg_dynamic_integer(.side_u32, _val, SIDE_TYPE_DYNAMIC_INTEGER, false, _byte_order, sizeof(uint32_t), 0, SIDE_PARAM(_attr))
-#define _side_arg_dynamic_u64(_val, _byte_order, _attr) \
-       _side_arg_dynamic_integer(.side_u64, _val, SIDE_TYPE_DYNAMIC_INTEGER, false, _byte_order, sizeof(uint64_t), 0, SIDE_PARAM(_attr))
-
-#define _side_arg_dynamic_s16(_val, _byte_order, _attr) \
-       _side_arg_dynamic_integer(.side_s16, _val, SIDE_TYPE_DYNAMIC_INTEGER, true, _byte_order, sizeof(int16_t), 0, SIDE_PARAM(_attr))
-#define _side_arg_dynamic_s32(_val, _byte_order, _attr) \
-       _side_arg_dynamic_integer(.side_s32, _val, SIDE_TYPE_DYNAMIC_INTEGER, true, _byte_order, sizeof(int32_t), 0, SIDE_PARAM(_attr))
-#define _side_arg_dynamic_s64(_val, _byte_order, _attr) \
-       _side_arg_dynamic_integer(.side_s64, _val, SIDE_TYPE_DYNAMIC_INTEGER, true, _byte_order, sizeof(int64_t), 0, SIDE_PARAM(_attr))
-
-#define _side_arg_dynamic_pointer(_val, _byte_order, _attr) \
+#define side_arg_dynamic_u8(_val, _attr...) \
+       _side_arg_dynamic_integer(.side_u8, _val, SIDE_TYPE_DYNAMIC_INTEGER, false, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(uint8_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_s8(_val, _attr...) \
+       _side_arg_dynamic_integer(.side_s8, _val, SIDE_TYPE_DYNAMIC_INTEGER, true, SIDE_TYPE_BYTE_ORDER_HOST, sizeof(int8_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+
+#define _side_arg_dynamic_u16(_val, _byte_order, _attr...) \
+       _side_arg_dynamic_integer(.side_u16, _val, SIDE_TYPE_DYNAMIC_INTEGER, false, _byte_order, sizeof(uint16_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define _side_arg_dynamic_u32(_val, _byte_order, _attr...) \
+       _side_arg_dynamic_integer(.side_u32, _val, SIDE_TYPE_DYNAMIC_INTEGER, false, _byte_order, sizeof(uint32_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define _side_arg_dynamic_u64(_val, _byte_order, _attr...) \
+       _side_arg_dynamic_integer(.side_u64, _val, SIDE_TYPE_DYNAMIC_INTEGER, false, _byte_order, sizeof(uint64_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+
+#define _side_arg_dynamic_s16(_val, _byte_order, _attr...) \
+       _side_arg_dynamic_integer(.side_s16, _val, SIDE_TYPE_DYNAMIC_INTEGER, true, _byte_order, sizeof(int16_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define _side_arg_dynamic_s32(_val, _byte_order, _attr...) \
+       _side_arg_dynamic_integer(.side_s32, _val, SIDE_TYPE_DYNAMIC_INTEGER, true, _byte_order, sizeof(int32_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define _side_arg_dynamic_s64(_val, _byte_order, _attr...) \
+       _side_arg_dynamic_integer(.side_s64, _val, SIDE_TYPE_DYNAMIC_INTEGER, true, _byte_order, sizeof(int64_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+
+#define _side_arg_dynamic_pointer(_val, _byte_order, _attr...) \
        _side_arg_dynamic_integer(.side_uptr, (uintptr_t) (_val), SIDE_TYPE_DYNAMIC_POINTER, false, _byte_order, \
-                       sizeof(uintptr_t), 0, SIDE_PARAM(_attr))
+                       sizeof(uintptr_t), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
-#define _side_arg_dynamic_float(_field, _val, _type, _byte_order, _float_size, _attr) \
+#define _side_arg_dynamic_float(_field, _val, _type, _byte_order, _float_size, _attr...) \
        { \
                .type = _type, \
                .u = { \
                        .side_dynamic = { \
                                .side_float = { \
                                        .type = { \
-                                               .attr = _attr, \
-                                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                                               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                                               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                                .float_size = _float_size, \
                                                .byte_order = _byte_order, \
                                        }, \
@@ -1538,53 +1619,53 @@ struct side_event_description {
                }, \
        }
 
-#define _side_arg_dynamic_float_binary16(_val, _byte_order, _attr) \
-       _side_arg_dynamic_float(.side_float_binary16, _val, SIDE_TYPE_DYNAMIC_FLOAT, _byte_order, sizeof(_Float16), SIDE_PARAM(_attr))
-#define _side_arg_dynamic_float_binary32(_val, _byte_order, _attr) \
-       _side_arg_dynamic_float(.side_float_binary32, _val, SIDE_TYPE_DYNAMIC_FLOAT, _byte_order, sizeof(_Float32), SIDE_PARAM(_attr))
-#define _side_arg_dynamic_float_binary64(_val, _byte_order, _attr) \
-       _side_arg_dynamic_float(.side_float_binary64, _val, SIDE_TYPE_DYNAMIC_FLOAT, _byte_order, sizeof(_Float64), SIDE_PARAM(_attr))
-#define _side_arg_dynamic_float_binary128(_val, _byte_order, _attr) \
-       _side_arg_dynamic_float(.side_float_binary128, _val, SIDE_TYPE_DYNAMIC_FLOAT, _byte_order, sizeof(_Float128), SIDE_PARAM(_attr))
+#define _side_arg_dynamic_float_binary16(_val, _byte_order, _attr...) \
+       _side_arg_dynamic_float(.side_float_binary16, _val, SIDE_TYPE_DYNAMIC_FLOAT, _byte_order, sizeof(_Float16), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define _side_arg_dynamic_float_binary32(_val, _byte_order, _attr...) \
+       _side_arg_dynamic_float(.side_float_binary32, _val, SIDE_TYPE_DYNAMIC_FLOAT, _byte_order, sizeof(_Float32), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define _side_arg_dynamic_float_binary64(_val, _byte_order, _attr...) \
+       _side_arg_dynamic_float(.side_float_binary64, _val, SIDE_TYPE_DYNAMIC_FLOAT, _byte_order, sizeof(_Float64), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define _side_arg_dynamic_float_binary128(_val, _byte_order, _attr...) \
+       _side_arg_dynamic_float(.side_float_binary128, _val, SIDE_TYPE_DYNAMIC_FLOAT, _byte_order, sizeof(_Float128), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
 /* Host endian */
-#define side_arg_dynamic_u16(_val, _attr)              _side_arg_dynamic_u16(_val, SIDE_TYPE_BYTE_ORDER_HOST, SIDE_PARAM(_attr))
-#define side_arg_dynamic_u32(_val, _attr)              _side_arg_dynamic_u32(_val, SIDE_TYPE_BYTE_ORDER_HOST, SIDE_PARAM(_attr))
-#define side_arg_dynamic_u64(_val, _attr)              _side_arg_dynamic_u64(_val, SIDE_TYPE_BYTE_ORDER_HOST, SIDE_PARAM(_attr))
-#define side_arg_dynamic_s16(_val, _attr)              _side_arg_dynamic_s16(_val, SIDE_TYPE_BYTE_ORDER_HOST, SIDE_PARAM(_attr))
-#define side_arg_dynamic_s32(_val, _attr)              _side_arg_dynamic_s32(_val, SIDE_TYPE_BYTE_ORDER_HOST, SIDE_PARAM(_attr))
-#define side_arg_dynamic_s64(_val, _attr)              _side_arg_dynamic_s64(_val, SIDE_TYPE_BYTE_ORDER_HOST, SIDE_PARAM(_attr))
-#define side_arg_dynamic_pointer(_val, _attr)          _side_arg_dynamic_pointer(_val, SIDE_TYPE_BYTE_ORDER_HOST, SIDE_PARAM(_attr))
-#define side_arg_dynamic_float_binary16(_val, _attr)   _side_arg_dynamic_float_binary16(_val, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, SIDE_PARAM(_attr))
-#define side_arg_dynamic_float_binary32(_val, _attr)   _side_arg_dynamic_float_binary32(_val, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, SIDE_PARAM(_attr))
-#define side_arg_dynamic_float_binary64(_val, _attr)   _side_arg_dynamic_float_binary64(_val, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, SIDE_PARAM(_attr))
-#define side_arg_dynamic_float_binary128(_val, _attr)  _side_arg_dynamic_float_binary128(_val, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, SIDE_PARAM(_attr))
+#define side_arg_dynamic_u16(_val, _attr...)                   _side_arg_dynamic_u16(_val, SIDE_TYPE_BYTE_ORDER_HOST, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_u32(_val, _attr...)                   _side_arg_dynamic_u32(_val, SIDE_TYPE_BYTE_ORDER_HOST, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_u64(_val, _attr...)                   _side_arg_dynamic_u64(_val, SIDE_TYPE_BYTE_ORDER_HOST, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_s16(_val, _attr...)                   _side_arg_dynamic_s16(_val, SIDE_TYPE_BYTE_ORDER_HOST, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_s32(_val, _attr...)                   _side_arg_dynamic_s32(_val, SIDE_TYPE_BYTE_ORDER_HOST, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_s64(_val, _attr...)                   _side_arg_dynamic_s64(_val, SIDE_TYPE_BYTE_ORDER_HOST, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_pointer(_val, _attr...)               _side_arg_dynamic_pointer(_val, SIDE_TYPE_BYTE_ORDER_HOST, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_float_binary16(_val, _attr...)                _side_arg_dynamic_float_binary16(_val, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_float_binary32(_val, _attr...)                _side_arg_dynamic_float_binary32(_val, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_float_binary64(_val, _attr...)                _side_arg_dynamic_float_binary64(_val, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_float_binary128(_val, _attr...)       _side_arg_dynamic_float_binary128(_val, SIDE_TYPE_FLOAT_WORD_ORDER_HOST, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
 /* Little endian */
-#define side_arg_dynamic_u16_le(_val, _attr)                   _side_arg_dynamic_u16(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_u32_le(_val, _attr)                   _side_arg_dynamic_u32(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_u64_le(_val, _attr)                   _side_arg_dynamic_u64(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_s16_le(_val, _attr)                   _side_arg_dynamic_s16(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_s32_le(_val, _attr)                   _side_arg_dynamic_s32(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_s64_le(_val, _attr)                   _side_arg_dynamic_s64(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_pointer_le(_val, _attr)               _side_arg_dynamic_pointer(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_float_binary16_le(_val, _attr)                _side_arg_dynamic_float_binary16(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_float_binary32_le(_val, _attr)                _side_arg_dynamic_float_binary32(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_float_binary64_le(_val, _attr)                _side_arg_dynamic_float_binary64(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_float_binary128_le(_val, _attr)       _side_arg_dynamic_float_binary128(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM(_attr))
+#define side_arg_dynamic_u16_le(_val, _attr...)                _side_arg_dynamic_u16(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_u32_le(_val, _attr...)                _side_arg_dynamic_u32(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_u64_le(_val, _attr...)                _side_arg_dynamic_u64(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_s16_le(_val, _attr...)                _side_arg_dynamic_s16(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_s32_le(_val, _attr...)                _side_arg_dynamic_s32(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_s64_le(_val, _attr...)                _side_arg_dynamic_s64(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_pointer_le(_val, _attr...)            _side_arg_dynamic_pointer(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_float_binary16_le(_val, _attr...)     _side_arg_dynamic_float_binary16(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_float_binary32_le(_val, _attr...)     _side_arg_dynamic_float_binary32(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_float_binary64_le(_val, _attr...)     _side_arg_dynamic_float_binary64(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_float_binary128_le(_val, _attr...)    _side_arg_dynamic_float_binary128(_val, SIDE_TYPE_BYTE_ORDER_LE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
 /* Big endian */
-#define side_arg_dynamic_u16_be(_val, _attr)                   _side_arg_dynamic_u16(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_u32_be(_val, _attr)                   _side_arg_dynamic_u32(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_u64_be(_val, _attr)                   _side_arg_dynamic_u64(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_s16_be(_val, _attr)                   _side_arg_dynamic_s16(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_s32_be(_val, _attr)                   _side_arg_dynamic_s32(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_s64_be(_val, _attr)                   _side_arg_dynamic_s64(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_pointer_be(_val, _attr)               _side_arg_dynamic_pointer(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_float_binary16_be(_val, _attr)                _side_arg_dynamic_float_binary16(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_float_binary32_be(_val, _attr)                _side_arg_dynamic_float_binary32(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_float_binary64_be(_val, _attr)                _side_arg_dynamic_float_binary64(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM(_attr))
-#define side_arg_dynamic_float_binary128_be(_val, _attr)       _side_arg_dynamic_float_binary128(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM(_attr))
+#define side_arg_dynamic_u16_be(_val, _attr...)                _side_arg_dynamic_u16(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_u32_be(_val, _attr...)                _side_arg_dynamic_u32(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_u64_be(_val, _attr...)                _side_arg_dynamic_u64(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_s16_be(_val, _attr...)                _side_arg_dynamic_s16(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_s32_be(_val, _attr...)                _side_arg_dynamic_s32(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_s64_be(_val, _attr...)                _side_arg_dynamic_s64(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_pointer_be(_val, _attr...)            _side_arg_dynamic_pointer(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_float_binary16_be(_val, _attr...)     _side_arg_dynamic_float_binary16(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_float_binary32_be(_val, _attr...)     _side_arg_dynamic_float_binary32(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_float_binary64_be(_val, _attr...)     _side_arg_dynamic_float_binary64(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
+#define side_arg_dynamic_float_binary128_be(_val, _attr...)    _side_arg_dynamic_float_binary128(_val, SIDE_TYPE_BYTE_ORDER_BE, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
 #define side_arg_dynamic_vla(_vla) \
        { \
@@ -1596,7 +1677,7 @@ struct side_event_description {
                }, \
        }
 
-#define side_arg_dynamic_vla_visitor(_dynamic_vla_visitor, _ctx, _attr) \
+#define side_arg_dynamic_vla_visitor(_dynamic_vla_visitor, _ctx, _attr...) \
        { \
                .type = SIDE_TYPE_DYNAMIC_VLA_VISITOR, \
                .u = { \
@@ -1604,8 +1685,8 @@ struct side_event_description {
                                .side_dynamic_vla_visitor = { \
                                        .app_ctx = _ctx, \
                                        .visitor = _dynamic_vla_visitor, \
-                                       .attr = _attr, \
-                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                                       .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                }, \
                        }, \
                }, \
@@ -1621,7 +1702,7 @@ struct side_event_description {
                }, \
        }
 
-#define side_arg_dynamic_struct_visitor(_dynamic_struct_visitor, _ctx, _attr) \
+#define side_arg_dynamic_struct_visitor(_dynamic_struct_visitor, _ctx, _attr...) \
        { \
                .type = SIDE_TYPE_DYNAMIC_STRUCT_VISITOR, \
                .u = { \
@@ -1629,29 +1710,29 @@ struct side_event_description {
                                .side_dynamic_struct_visitor = { \
                                        .app_ctx = _ctx, \
                                        .visitor = _dynamic_struct_visitor, \
-                                       .attr = _attr, \
-                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                                       .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
+                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                                }, \
                        }, \
                }, \
        }
 
-#define side_arg_dynamic_define_vec(_identifier, _sav, _attr) \
+#define side_arg_dynamic_define_vec(_identifier, _sav, _attr...) \
        const struct side_arg _identifier##_vec[] = { _sav }; \
        const struct side_arg_dynamic_vla _identifier = { \
                .sav = _identifier##_vec, \
-               .attr = _attr, \
+               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
                .len = SIDE_ARRAY_SIZE(_identifier##_vec), \
-               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
        }
 
-#define side_arg_dynamic_define_struct(_identifier, _struct_fields, _attr) \
+#define side_arg_dynamic_define_struct(_identifier, _struct_fields, _attr...) \
        const struct side_arg_dynamic_field _identifier##_fields[] = { _struct_fields }; \
        const struct side_arg_dynamic_struct _identifier = { \
                .fields = _identifier##_fields, \
-               .attr = _attr, \
+               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
                .len = SIDE_ARRAY_SIZE(_identifier##_fields), \
-               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
        }
 
 #define side_arg_define_vec(_identifier, _sav) \
@@ -1692,7 +1773,7 @@ struct side_event_description {
        side_event_cond(_identifier) \
                side_event_call(_identifier, SIDE_PARAM(_sav))
 
-#define side_event_call_variadic(_identifier, _sav, _var_fields, _attr) \
+#define side_event_call_variadic(_identifier, _sav, _var_fields, _attr...) \
        { \
                const struct side_arg side_sav[] = { _sav }; \
                const struct side_arg_vec side_arg_vec = { \
@@ -1702,18 +1783,18 @@ struct side_event_description {
                const struct side_arg_dynamic_field side_fields[] = { _var_fields }; \
                const struct side_arg_dynamic_struct var_struct = { \
                        .fields = side_fields, \
-                       .attr = _attr, \
+                       .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
                        .len = SIDE_ARRAY_SIZE(side_fields), \
-                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                }; \
                side_call_variadic(&(_identifier), &side_arg_vec, &var_struct); \
        }
 
-#define side_event_variadic(_identifier, _sav, _var, _attr) \
+#define side_event_variadic(_identifier, _sav, _var, _attr...) \
        side_event_cond(_identifier) \
-               side_event_call_variadic(_identifier, SIDE_PARAM(_sav), SIDE_PARAM(_var), SIDE_PARAM(_attr))
+               side_event_call_variadic(_identifier, SIDE_PARAM(_sav), SIDE_PARAM(_var), SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
-#define _side_define_event(_linkage, _identifier, _provider, _event, _loglevel, _fields, _attr, _flags) \
+#define _side_define_event(_linkage, _identifier, _provider, _event, _loglevel, _fields, _flags, _attr...) \
        _linkage uintptr_t side_event_enable__##_identifier __attribute__((section("side_event_enable"))); \
        _linkage struct side_event_description __attribute__((section("side_event_description"))) \
                        _identifier = { \
@@ -1721,41 +1802,41 @@ struct side_event_description {
                .provider_name = _provider, \
                .event_name = _event, \
                .fields = _fields, \
-               .attr = _attr, \
+               .attr = SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()), \
                .callbacks = &side_empty_callback, \
                .flags = (_flags), \
                .version = 0, \
                .loglevel = _loglevel, \
                .nr_fields = SIDE_ARRAY_SIZE(SIDE_PARAM(_fields)), \
-               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM(_attr)), \
+               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
                .nr_callbacks = 0, \
        }; \
        static const struct side_event_description *side_event_ptr__##_identifier \
                __attribute__((section("side_event_description_ptr"), used)) = &(_identifier);
 
-#define side_static_event(_identifier, _provider, _event, _loglevel, _fields, _attr) \
+#define side_static_event(_identifier, _provider, _event, _loglevel, _fields, _attr...) \
        _side_define_event(static, _identifier, _provider, _event, _loglevel, SIDE_PARAM(_fields), \
-                       SIDE_PARAM(_attr), 0)
+                       0, ##_attr)
 
-#define side_static_event_variadic(_identifier, _provider, _event, _loglevel, _fields, _attr) \
+#define side_static_event_variadic(_identifier, _provider, _event, _loglevel, _fields, _attr...) \
        _side_define_event(static, _identifier, _provider, _event, _loglevel, SIDE_PARAM(_fields), \
-                       SIDE_PARAM(_attr), SIDE_EVENT_FLAG_VARIADIC)
+                       SIDE_EVENT_FLAG_VARIADIC, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
-#define side_hidden_event(_identifier, _provider, _event, _loglevel, _fields, _attr) \
+#define side_hidden_event(_identifier, _provider, _event, _loglevel, _fields, _attr...) \
        _side_define_event(__attribute__((visibility("hidden"))), _identifier, _provider, _event, \
-                       _loglevel, SIDE_PARAM(_fields), SIDE_PARAM(_attr), 0)
+                       _loglevel, SIDE_PARAM(_fields), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
-#define side_hidden_event_variadic(_identifier, _provider, _event, _loglevel, _fields, _attr) \
+#define side_hidden_event_variadic(_identifier, _provider, _event, _loglevel, _fields, _attr...) \
        _side_define_event(__attribute__((visibility("hidden"))), _identifier, _provider, _event, \
-                       _loglevel, SIDE_PARAM(_fields), SIDE_PARAM(_attr), SIDE_EVENT_FLAG_VARIADIC)
+                       _loglevel, SIDE_PARAM(_fields), SIDE_EVENT_FLAG_VARIADIC, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
-#define side_export_event(_identifier, _provider, _event, _loglevel, _fields, _attr) \
+#define side_export_event(_identifier, _provider, _event, _loglevel, _fields, _attr...) \
        _side_define_event(__attribute__((visibility("default"))), _identifier, _provider, _event, \
-                       _loglevel, SIDE_PARAM(_fields), SIDE_PARAM(_attr), 0)
+                       _loglevel, SIDE_PARAM(_fields), 0, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
-#define side_export_event_variadic(_identifier, _provider, _event, _loglevel, _fields, _attr) \
+#define side_export_event_variadic(_identifier, _provider, _event, _loglevel, _fields, _attr...) \
        _side_define_event(__attribute__((visibility("default"))), _identifier, _provider, _event, \
-                       _loglevel, SIDE_PARAM(_fields), SIDE_PARAM(_attr), SIDE_EVENT_FLAG_VARIADIC)
+                       _loglevel, SIDE_PARAM(_fields), SIDE_EVENT_FLAG_VARIADIC, SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list()))
 
 #define side_declare_event(_identifier) \
        extern uintptr_t side_event_enable_##_identifier; \
@@ -1820,8 +1901,8 @@ void side_tracer_event_notification_unregister(struct side_tracer_handle *handle
  * Explicit hooks to initialize/finalize the side instrumentation
  * library. Those are also library constructor/destructor.
  */
-void side_init(void);
-void side_exit(void);
+void side_init(void) __attribute__((constructor));
+void side_exit(void) __attribute__((destructor));
 
 /*
  * The following constructors/destructors perform automatic registration