Update struct event_packet_context

[ctf.git] / common-trace-format-specification.txt

diff --git a/common-trace-format-specification.txt b/common-trace-format-specification.txt
index 8d5cc928b264fc1a11bdb72655a394236d8d1d52..e8c9e48f6d87145e20a4c4af7a7bf5cc6cedc729 100644 (file)
--- a/common-trace-format-specification.txt
+++ b/common-trace-format-specification.txt
@@ -415,8 +415,11 @@ struct example {
   uint64_t second_field_name;  /* Named type declared in the meta-data */
 };
 
-The fields are placed in a sequence next to each other. They each possess a
-field name, which is a unique identifier within the structure.
+The fields are placed in a sequence next to each other. They each
+possess a field name, which is a unique identifier within the structure.
+The identifier is not allowed to use any reserved keyword
+(see Section C.1.2). Replacing reserved keywords with
+underscore-prefixed field names is recommended.
 
 A nameless structure can be declared as a field type or as part of a typedef:
 
@@ -454,6 +457,11 @@ containing the variant is independent of the variant alignment.  The size of the
 variant is the size as selected by the tag value for the specific instance of
 the variant.
 
+Each variant type selector possess a field name, which is a unique
+identifier within the variant. The identifier is not allowed to use any
+reserved keyword (see Section C.1.2). Replacing reserved keywords with
+underscore-prefixed field names is recommended.
+
 A named variant declaration followed by its definition within a structure
 declaration:
 
@@ -744,7 +752,6 @@ struct event_packet_context {
   uint32_t cpu_id;
   uint32_t/uint16_t content_size;
   uint32_t/uint16_t packet_size;
-  uint8_t  stream_packet_count_bits;   /* Significant counter bits */
   uint8_t  compression_scheme;
   uint8_t  encryption_scheme;
   uint8_t  checksum_scheme;
@@ -933,7 +940,21 @@ CTF stream packet facilities (checksumming, compression, encryption,
 network-readiness) for meta-data stream generated and transported by a
 tracer.
 
-The text-only meta-data file is a plain text TSDL description.
+The text-only meta-data file is a plain-text TSDL description. This file
+must begin with the following characters to identify the file as a CTF
+TSDL text-based metadata file (without the double-quotes) :
+
+"/* CTF"
+
+It must be followed by a space, and the version of the specification
+followed by the CTF trace, e.g.:
+
+" 1.8"
+
+These characters allow automated discovery of file type and CTF
+specification version. They are interpreted as a the beginning of a
+comment by the TSDL metadata parser.  The comment can be continued to
+contain extra commented characters before it is closed.
 
 The packet-based meta-data is made of "meta-data packets", which each
 start with a meta-data packet header. The packet-based meta-data
@@ -958,6 +979,8 @@ struct metadata_packet_header {
   uint8_t  compression_scheme;         /* 0 if unused */
   uint8_t  encryption_scheme;          /* 0 if unused */
   uint8_t  checksum_scheme;            /* 0 if unused */
+  uint8_t  major;                      /* CTF spec version major number */
+  uint8_t  minor;                      /* CTF spec version minor number */
 };
 
 The packet-based meta-data can be converted to a text-only meta-data by
@@ -1029,9 +1052,8 @@ associated with a variant, and to lookup up the location of the length
 field associated with a sequence.
 
 Variants and sequences can refer to a tag field either using a relative
-path or an absolute path. The relative path starts with "." to ensure
-there are no conflicts with dynamic scope names. It is relative to the
-scope in which the variant or sequence performing the lookup is located.
+path or an absolute path. The relative path is relative to the scope in
+which the variant or sequence performing the lookup is located.
 Relative paths are only allowed to lookup within the same static scope,
 which includes its nested static scopes. Lookups targeting parent static
 scopes need to be performed with an absolute path.
@@ -1056,15 +1078,13 @@ The dynamic scope prefixes are thus:
 
 
 The target dynamic scope must be specified explicitly when referring to
-a field outside of the static scope (absolute scope reference).
-References to fields within the static scope (including local static
-scopes and nested static scopes) can be referenced by using a relative
-reference (starting with ".").
-
-As a matter of convenience, the leading "." in relative paths can be
-omitted. In case of conflict between relative and dynamic paths, the
-relative path is preferred. It is recommended to use the "." prefix for
-relative paths to ensure no path name conflict can occur.
+a field outside of the static scope (absolute scope reference). No
+conflict can occur between relative and dynamic paths, because the
+keywords "trace", "stream", and "event" are reserved, and thus
+not permitted as field names. It is recommended that field names
+clashing with CTF and C99 reserved keywords use an underscore prefix to
+eliminate the risk of generating a description containing an invalid
+field name.
 
 The information available in the dynamic scopes can be thought of as the
 current tracing context. At trace production, information about the
@@ -1108,9 +1128,11 @@ stream {
 };
 
 event {
-  name = event_name;
+  name = "event_name";
   id = value;                  /* Numeric identifier within the stream */
   stream_id = stream_id;
+  loglevel.identifier = "loglevel_identifier";
+  loglevel.value = value;
   context := struct {
     ...
   };