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4dfca05b 1Common Trace Format (CTF) Specification (pre-v1.8)
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2
3Mathieu Desnoyers, EfficiOS Inc.
4
339a7dde 5The goal of the present document is to specify a trace format that suits the
cc089c3a 6needs of the embedded, telecom, high-performance and kernel communities. It is
5ba9f198 7based on the Common Trace Format Requirements (v1.4) document. It is designed to
cc089c3a 8allow traces to be natively generated by the Linux kernel, Linux user-space
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9applications written in C/C++, and hardware components. One major element of
10CTF is the Trace Stream Description Language (TSDL) which flexibility
11enables description of various binary trace stream layouts.
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12
13The latest version of this document can be found at:
14
15 git tree: git://git.efficios.com/ctf.git
16 gitweb: http://git.efficios.com/?p=ctf.git
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17
18A reference implementation of a library to read and write this trace format is
19being implemented within the BabelTrace project, a converter between trace
20formats. The development tree is available at:
21
22 git tree: git://git.efficios.com/babeltrace.git
23 gitweb: http://git.efficios.com/?p=babeltrace.git
24
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25The CE Workgroup of the Linux Foundation, Ericsson, and EfficiOS have
26sponsored this work.
27
5ba9f198 28
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29Table of Contents
30
311. Preliminary definitions
322. High-level representation of a trace
333. Event stream
344. Types
35 4.1 Basic types
36 4.1.1 Type inheritance
37 4.1.2 Alignment
38 4.1.3 Byte order
39 4.1.4 Size
40 4.1.5 Integers
41 4.1.6 GNU/C bitfields
42 4.1.7 Floating point
43 4.1.8 Enumerations
444.2 Compound types
45 4.2.1 Structures
46 4.2.2 Variants (Discriminated/Tagged Unions)
47 4.2.3 Arrays
48 4.2.4 Sequences
49 4.2.5 Strings
505. Event Packet Header
51 5.1 Event Packet Header Description
52 5.2 Event Packet Context Description
536. Event Structure
54 6.1 Event Header
55 6.1.1 Type 1 - Few event IDs
56 6.1.2 Type 2 - Many event IDs
57 6.2 Event Context
58 6.3 Event Payload
59 6.3.1 Padding
60 6.3.2 Alignment
617. Trace Stream Description Language (TSDL)
62 7.1 Meta-data
63 7.2 Declaration vs Definition
64 7.3 TSDL Scopes
65 7.3.1 Lexical Scope
37ab95c3 66 7.3.2 Static and Dynamic Scopes
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67 7.4 TSDL Examples
68
69
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701. Preliminary definitions
71
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72 - Event Trace: An ordered sequence of events.
73 - Event Stream: An ordered sequence of events, containing a subset of the
74 trace event types.
75 - Event Packet: A sequence of physically contiguous events within an event
76 stream.
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77 - Event: This is the basic entry in a trace. (aka: a trace record).
78 - An event identifier (ID) relates to the class (a type) of event within
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79 an event stream.
80 e.g. event: irq_entry.
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81 - An event (or event record) relates to a specific instance of an event
82 class.
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83 e.g. event: irq_entry, at time X, on CPU Y
84 - Source Architecture: Architecture writing the trace.
85 - Reader Architecture: Architecture reading the trace.
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86
87
882. High-level representation of a trace
89
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90A trace is divided into multiple event streams. Each event stream contains a
91subset of the trace event types.
5ba9f198 92
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93The final output of the trace, after its generation and optional transport over
94the network, is expected to be either on permanent or temporary storage in a
95virtual file system. Because each event stream is appended to while a trace is
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96being recorded, each is associated with a distinct set of files for
97output. Therefore, a stored trace can be represented as a directory
98containing zero, one or more files per stream.
5ba9f198 99
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100Meta-data description associated with the trace contains information on
101trace event types expressed in the Trace Stream Description Language
102(TSDL). This language describes:
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103
104- Trace version.
105- Types available.
6672e9e1 106- Per-trace event header description.
3bf79539 107- Per-stream event header description.
6672e9e1 108- Per-stream event context description.
5ba9f198 109- Per-event
3bf79539 110 - Event type to stream mapping.
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111 - Event type to name mapping.
112 - Event type to ID mapping.
6672e9e1 113 - Event context description.
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114 - Event fields description.
115
116
3bf79539 1173. Event stream
5ba9f198 118
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119An event stream can be divided into contiguous event packets of variable
120size. These subdivisions have a variable size. An event packet can
121contain a certain amount of padding at the end. The stream header is
122repeated at the beginning of each event packet. The rationale for the
123event stream design choices is explained in Appendix B. Stream Header
124Rationale.
5ba9f198 125
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126The event stream header will therefore be referred to as the "event packet
127header" throughout the rest of this document.
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128
129
1304. Types
131
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132Types are organized as type classes. Each type class belong to either of two
133kind of types: basic types or compound types.
134
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1354.1 Basic types
136
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137A basic type is a scalar type, as described in this section. It includes
138integers, GNU/C bitfields, enumerations, and floating point values.
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139
1404.1.1 Type inheritance
141
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142Type specifications can be inherited to allow deriving types from a
143type class. For example, see the uint32_t named type derived from the "integer"
144type class below ("Integers" section). Types have a precise binary
145representation in the trace. A type class has methods to read and write these
146types, but must be derived into a type to be usable in an event field.
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147
1484.1.2 Alignment
149
150We define "byte-packed" types as aligned on the byte size, namely 8-bit.
151We define "bit-packed" types as following on the next bit, as defined by the
370eae99 152"Integers" section.
5ba9f198 153
6672e9e1 154Each basic type must specify its alignment, in bits. Examples of
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155possible alignments are: bit-packed (align = 1), byte-packed (align =
1568), or word-aligned (e.g. align = 32 or align = 64). The choice depends
157on the architecture preference and compactness vs performance trade-offs
158of the implementation. Architectures providing fast unaligned write
159byte-packed basic types to save space, aligning each type on byte
160boundaries (8-bit). Architectures with slow unaligned writes align types
161on specific alignment values. If no specific alignment is declared for a
162type, it is assumed to be bit-packed for integers with size not multiple
163of 8 bits and for gcc bitfields. All other basic types are byte-packed
164by default. It is however recommended to always specify the alignment
165explicitly. Alignment values must be power of two. Compound types are
166aligned as specified in their individual specification.
5ba9f198 167
6672e9e1 168TSDL meta-data attribute representation of a specific alignment:
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169
170 align = value; /* value in bits */
171
1724.1.3 Byte order
173
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174By default, the native endianness of the source architecture the trace is used.
175Byte order can be overridden for a basic type by specifying a "byte_order"
176attribute. Typical use-case is to specify the network byte order (big endian:
177"be") to save data captured from the network into the trace without conversion.
178If not specified, the byte order is native.
5ba9f198 179
6672e9e1 180TSDL meta-data representation:
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181
182 byte_order = native OR network OR be OR le; /* network and be are aliases */
183
1844.1.4 Size
185
186Type size, in bits, for integers and floats is that returned by "sizeof()" in C
187multiplied by CHAR_BIT.
188We require the size of "char" and "unsigned char" types (CHAR_BIT) to be fixed
189to 8 bits for cross-endianness compatibility.
190
6672e9e1 191TSDL meta-data representation:
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192
193 size = value; (value is in bits)
194
1954.1.5 Integers
196
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197Signed integers are represented in two-complement. Integer alignment,
198size, signedness and byte ordering are defined in the TSDL meta-data.
199Integers aligned on byte size (8-bit) and with length multiple of byte
200size (8-bit) correspond to the C99 standard integers. In addition,
201integers with alignment and/or size that are _not_ a multiple of the
202byte size are permitted; these correspond to the C99 standard bitfields,
203with the added specification that the CTF integer bitfields have a fixed
204binary representation. A MIT-licensed reference implementation of the
205CTF portable bitfields is available at:
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206
207 http://git.efficios.com/?p=babeltrace.git;a=blob;f=include/babeltrace/bitfield.h
208
209Binary representation of integers:
210
211- On little and big endian:
212 - Within a byte, high bits correspond to an integer high bits, and low bits
213 correspond to low bits.
214- On little endian:
215 - Integer across multiple bytes are placed from the less significant to the
216 most significant.
217 - Consecutive integers are placed from lower bits to higher bits (even within
218 a byte).
219- On big endian:
220 - Integer across multiple bytes are placed from the most significant to the
221 less significant.
222 - Consecutive integers are placed from higher bits to lower bits (even within
223 a byte).
224
225This binary representation is derived from the bitfield implementation in GCC
226for little and big endian. However, contrary to what GCC does, integers can
6672e9e1 227cross units boundaries (no padding is required). Padding can be explicitly
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228added (see 4.1.6 GNU/C bitfields) to follow the GCC layout if needed.
229
6672e9e1 230TSDL meta-data representation:
5ba9f198 231
80fd2569 232 integer {
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233 signed = true OR false; /* default false */
234 byte_order = native OR network OR be OR le; /* default native */
235 size = value; /* value in bits, no default */
236 align = value; /* value in bits */
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237 /* based used for pretty-printing output, default: decimal. */
238 base = decimal OR dec OR OR d OR i OR u OR 10 OR hexadecimal OR hex OR x OR X OR p OR 16
239 OR octal OR oct OR o OR 8 OR binary OR b OR 2;
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240 /* character encoding, default: none */
241 encoding = none or UTF8 or ASCII;
2152348f 242 }
5ba9f198 243
80fd2569 244Example of type inheritance (creation of a uint32_t named type):
5ba9f198 245
359894ac 246typealias integer {
9e4e34e9 247 size = 32;
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248 signed = false;
249 align = 32;
38b8da21 250} := uint32_t;
5ba9f198 251
80fd2569 252Definition of a named 5-bit signed bitfield:
5ba9f198 253
359894ac 254typealias integer {
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255 size = 5;
256 signed = true;
257 align = 1;
38b8da21 258} := int5_t;
5ba9f198 259
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260The character encoding field can be used to specify that the integer
261must be printed as a text character when read. e.g.:
262
263typealias integer {
264 size = 8;
265 align = 8;
266 signed = false;
267 encoding = UTF8;
268} := utf_char;
269
270
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2714.1.6 GNU/C bitfields
272
273The GNU/C bitfields follow closely the integer representation, with a
274particularity on alignment: if a bitfield cannot fit in the current unit, the
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275unit is padded and the bitfield starts at the following unit. The unit size is
276defined by the size of the type "unit_type".
5ba9f198 277
6672e9e1 278TSDL meta-data representation:
80fd2569 279
d674f4b8 280 unit_type name:size;
80fd2569 281
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282As an example, the following structure declared in C compiled by GCC:
283
284struct example {
285 short a:12;
286 short b:5;
287};
288
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289The example structure is aligned on the largest element (short). The second
290bitfield would be aligned on the next unit boundary, because it would not fit in
291the current unit.
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292
2934.1.7 Floating point
294
6672e9e1 295The floating point values byte ordering is defined in the TSDL meta-data.
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296
297Floating point values follow the IEEE 754-2008 standard interchange formats.
298Description of the floating point values include the exponent and mantissa size
299in bits. Some requirements are imposed on the floating point values:
300
301- FLT_RADIX must be 2.
302- mant_dig is the number of digits represented in the mantissa. It is specified
303 by the ISO C99 standard, section 5.2.4, as FLT_MANT_DIG, DBL_MANT_DIG and
304 LDBL_MANT_DIG as defined by <float.h>.
305- exp_dig is the number of digits represented in the exponent. Given that
306 mant_dig is one bit more than its actual size in bits (leading 1 is not
307 needed) and also given that the sign bit always takes one bit, exp_dig can be
308 specified as:
309
310 - sizeof(float) * CHAR_BIT - FLT_MANT_DIG
311 - sizeof(double) * CHAR_BIT - DBL_MANT_DIG
312 - sizeof(long double) * CHAR_BIT - LDBL_MANT_DIG
313
6672e9e1 314TSDL meta-data representation:
5ba9f198 315
80fd2569 316floating_point {
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317 exp_dig = value;
318 mant_dig = value;
319 byte_order = native OR network OR be OR le;
320 align = value;
2152348f 321}
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322
323Example of type inheritance:
324
359894ac 325typealias floating_point {
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326 exp_dig = 8; /* sizeof(float) * CHAR_BIT - FLT_MANT_DIG */
327 mant_dig = 24; /* FLT_MANT_DIG */
328 byte_order = native;
ec4404a7 329 align = 32;
38b8da21 330} := float;
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331
332TODO: define NaN, +inf, -inf behavior.
333
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334Bit-packed, byte-packed or larger alignments can be used for floating
335point values, similarly to integers.
336
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3374.1.8 Enumerations
338
339Enumerations are a mapping between an integer type and a table of strings. The
340numerical representation of the enumeration follows the integer type specified
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341by the meta-data. The enumeration mapping table is detailed in the enumeration
342description within the meta-data. The mapping table maps inclusive value
343ranges (or single values) to strings. Instead of being limited to simple
3bf79539 344"value -> string" mappings, these enumerations map
80fd2569 345"[ start_value ... end_value ] -> string", which map inclusive ranges of
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346values to strings. An enumeration from the C language can be represented in
347this format by having the same start_value and end_value for each element, which
348is in fact a range of size 1. This single-value range is supported without
4767a9e7 349repeating the start and end values with the value = string declaration.
80fd2569 350
a9b83695 351enum name : integer_type {
359894ac 352 somestring = start_value1 ... end_value1,
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353 "other string" = start_value2 ... end_value2,
354 yet_another_string, /* will be assigned to end_value2 + 1 */
355 "some other string" = value,
356 ...
357};
358
359If the values are omitted, the enumeration starts at 0 and increment of 1 for
360each entry:
361
a9b83695 362enum name : unsigned int {
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363 ZERO,
364 ONE,
365 TWO,
366 TEN = 10,
367 ELEVEN,
3bf79539 368};
5ba9f198 369
80fd2569 370Overlapping ranges within a single enumeration are implementation defined.
5ba9f198 371
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372A nameless enumeration can be declared as a field type or as part of a typedef:
373
a9b83695 374enum : integer_type {
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375 ...
376}
377
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378Enumerations omitting the container type ": integer_type" use the "int"
379type (for compatibility with C99). The "int" type must be previously
380declared. E.g.:
381
382typealias integer { size = 32; align = 32; signed = true } := int;
383
384enum {
385 ...
386}
387
1fad7a85 388
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3894.2 Compound types
390
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391Compound are aggregation of type declarations. Compound types include
392structures, variant, arrays, sequences, and strings.
393
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3944.2.1 Structures
395
396Structures are aligned on the largest alignment required by basic types
397contained within the structure. (This follows the ISO/C standard for structures)
398
6672e9e1 399TSDL meta-data representation of a named structure:
5ba9f198 400
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401struct name {
402 field_type field_name;
403 field_type field_name;
404 ...
405};
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406
407Example:
408
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409struct example {
410 integer { /* Nameless type */
411 size = 16;
412 signed = true;
413 align = 16;
414 } first_field_name;
6672e9e1 415 uint64_t second_field_name; /* Named type declared in the meta-data */
3bf79539 416};
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417
418The fields are placed in a sequence next to each other. They each possess a
419field name, which is a unique identifier within the structure.
420
2152348f 421A nameless structure can be declared as a field type or as part of a typedef:
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422
423struct {
424 ...
2152348f 425}
80fd2569 426
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427Alignment for a structure compound type can be forced to a minimum value
428by adding an "align" specifier after the declaration of a structure
429body. This attribute is read as: align(value). The value is specified in
430bits. The structure will be aligned on the maximum value between this
431attribute and the alignment required by the basic types contained within
432the structure. e.g.
433
434struct {
435 ...
436} align(32)
437
77a98c82 4384.2.2 Variants (Discriminated/Tagged Unions)
fcba70d4 439
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440A CTF variant is a selection between different types. A CTF variant must
441always be defined within the scope of a structure or within fields
442contained within a structure (defined recursively). A "tag" enumeration
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443field must appear in either the same static scope, prior to the variant
444field (in field declaration order), in an upper static scope , or in an
445upper dynamic scope (see Section 7.3.2). The type selection is indicated
446by the mapping from the enumeration value to the string used as variant
447type selector. The field to use as tag is specified by the "tag_field",
448specified between "< >" after the "variant" keyword for unnamed
449variants, and after "variant name" for named variants.
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450
451The alignment of the variant is the alignment of the type as selected by the tag
452value for the specific instance of the variant. The alignment of the type
453containing the variant is independent of the variant alignment. The size of the
454variant is the size as selected by the tag value for the specific instance of
455the variant.
456
457A named variant declaration followed by its definition within a structure
458declaration:
459
460variant name {
461 field_type sel1;
462 field_type sel2;
463 field_type sel3;
464 ...
465};
466
467struct {
a9b83695 468 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
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469 ...
470 variant name <tag_field> v;
471}
472
473An unnamed variant definition within a structure is expressed by the following
6672e9e1 474TSDL meta-data:
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475
476struct {
a9b83695 477 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
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478 ...
479 variant <tag_field> {
480 field_type sel1;
481 field_type sel2;
482 field_type sel3;
483 ...
484 } v;
485}
486
487Example of a named variant within a sequence that refers to a single tag field:
488
489variant example {
490 uint32_t a;
491 uint64_t b;
492 short c;
493};
494
495struct {
a9b83695 496 enum : uint2_t { a, b, c } choice;
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497 unsigned int seqlen;
498 variant example <choice> v[seqlen];
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499}
500
501Example of an unnamed variant:
502
503struct {
a9b83695 504 enum : uint2_t { a, b, c, d } choice;
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505 /* Unrelated fields can be added between the variant and its tag */
506 int32_t somevalue;
507 variant <choice> {
508 uint32_t a;
509 uint64_t b;
510 short c;
511 struct {
512 unsigned int field1;
513 uint64_t field2;
514 } d;
515 } s;
516}
517
518Example of an unnamed variant within an array:
519
520struct {
a9b83695 521 enum : uint2_t { a, b, c } choice;
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522 variant <choice> {
523 uint32_t a;
524 uint64_t b;
525 short c;
15850440 526 } v[10];
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527}
528
529Example of a variant type definition within a structure, where the defined type
530is then declared within an array of structures. This variant refers to a tag
37ab95c3 531located in an upper static scope. This example clearly shows that a variant
fcba70d4 532type definition referring to the tag "x" uses the closest preceding field from
37ab95c3 533the static scope of the type definition.
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534
535struct {
a9b83695 536 enum : uint2_t { a, b, c, d } x;
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537
538 typedef variant <x> { /*
539 * "x" refers to the preceding "x" enumeration in the
37ab95c3 540 * static scope of the type definition.
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541 */
542 uint32_t a;
543 uint64_t b;
544 short c;
545 } example_variant;
546
547 struct {
a9b83695 548 enum : int { x, y, z } x; /* This enumeration is not used by "v". */
fcba70d4 549 example_variant v; /*
a9b83695 550 * "v" uses the "enum : uint2_t { a, b, c, d }"
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551 * tag.
552 */
553 } a[10];
554}
555
5564.2.3 Arrays
5ba9f198 557
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558Arrays are fixed-length. Their length is declared in the type
559declaration within the meta-data. They contain an array of "inner type"
560elements, which can refer to any type not containing the type of the
561array being declared (no circular dependency). The length is the number
562of elements in an array.
5ba9f198 563
6672e9e1 564TSDL meta-data representation of a named array:
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565
566typedef elem_type name[length];
5ba9f198 567
2152348f 568A nameless array can be declared as a field type within a structure, e.g.:
5ba9f198 569
2152348f 570 uint8_t field_name[10];
80fd2569 571
ec4404a7 572Arrays are always aligned on their element alignment requirement.
5ba9f198 573
fcba70d4 5744.2.4 Sequences
5ba9f198 575
1ab22b2a 576Sequences are dynamically-sized arrays. They refer to a a "length"
37ab95c3 577unsigned integer field, which must appear in either the same static scope,
1ab22b2a 578prior to the sequence field (in field declaration order), in an upper
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579static scope, or in an upper dynamic scope (see Section 7.3.2). This
580length field represents the number of elements in the sequence. The
581sequence per se is an array of "inner type" elements.
5ba9f198 582
1ab22b2a 583TSDL meta-data representation for a sequence type definition:
80fd2569 584
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585struct {
586 unsigned int length_field;
587 typedef elem_type typename[length_field];
588 typename seq_field_name;
589}
590
591A sequence can also be declared as a field type, e.g.:
80fd2569 592
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593struct {
594 unsigned int length_field;
595 long seq_field_name[length_field];
596}
80fd2569 597
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598Multiple sequences can refer to the same length field, and these length
599fields can be in a different upper dynamic scope:
600
601e.g., assuming the stream.event.header defines:
602
603stream {
604 ...
605 id = 1;
606 event.header := struct {
607 uint16_t seq_len;
608 };
609};
610
611event {
612 ...
613 stream_id = 1;
614 fields := struct {
615 long seq_a[stream.event.header.seq_len];
616 char seq_b[stream.event.header.seq_len];
617 };
618};
80fd2569 619
1ab22b2a 620The sequence elements follow the "array" specifications.
5ba9f198 621
fcba70d4 6224.2.5 Strings
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623
624Strings are an array of bytes of variable size and are terminated by a '\0'
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625"NULL" character. Their encoding is described in the TSDL meta-data. In
626absence of encoding attribute information, the default encoding is
627UTF-8.
5ba9f198 628
6672e9e1 629TSDL meta-data representation of a named string type:
80fd2569 630
359894ac 631typealias string {
5ba9f198 632 encoding = UTF8 OR ASCII;
38b8da21 633} := name;
5ba9f198 634
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635A nameless string type can be declared as a field type:
636
637string field_name; /* Use default UTF8 encoding */
5ba9f198 638
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639Strings are always aligned on byte size.
640
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6415. Event Packet Header
642
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643The event packet header consists of two parts: the "event packet header"
644is the same for all streams of a trace. The second part, the "event
645packet context", is described on a per-stream basis. Both are described
646in the TSDL meta-data. The packets are aligned on architecture-page-sized
647addresses.
3bf79539 648
6672e9e1 649Event packet header (all fields are optional, specified by TSDL meta-data):
3bf79539 650
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651- Magic number (CTF magic number: 0xC1FC1FC1) specifies that this is a
652 CTF packet. This magic number is optional, but when present, it should
653 come at the very beginning of the packet.
654- Trace UUID, used to ensure the event packet match the meta-data used.
655 (note: we cannot use a meta-data checksum in every cases instead of a
656 UUID because meta-data can be appended to while tracing is active)
657 This field is optional.
658- Stream ID, used as reference to stream description in meta-data.
659 This field is optional if there is only one stream description in the
660 meta-data, but becomes required if there are more than one stream in
661 the TSDL meta-data description.
3bf79539 662
6672e9e1 663Event packet context (all fields are optional, specified by TSDL meta-data):
3bf79539 664
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665- Event packet content size (in bits).
666- Event packet size (in bits, includes padding).
cda89682 667- Event packet content checksum. Checksum excludes the event packet
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668 header.
669- Per-stream event packet sequence count (to deal with UDP packet loss). The
670 number of significant sequence counter bits should also be present, so
b11853af 671 wrap-arounds are dealt with correctly.
6672e9e1 672- Time-stamp at the beginning and time-stamp at the end of the event packet.
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673 Both timestamps are written in the packet header, but sampled respectively
674 while (or before) writing the first event and while (or after) writing the
675 last event in the packet. The inclusive range between these timestamps should
676 include all event timestamps assigned to events contained within the packet.
5ba9f198 677- Events discarded count
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678 - Snapshot of a per-stream free-running counter, counting the number of
679 events discarded that were supposed to be written in the stream prior to
680 the first event in the event packet.
5ba9f198 681 * Note: producer-consumer buffer full condition should fill the current
3bf79539 682 event packet with padding so we know exactly where events have been
5ba9f198 683 discarded.
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684- Lossless compression scheme used for the event packet content. Applied
685 directly to raw data. New types of compression can be added in following
686 versions of the format.
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687 0: no compression scheme
688 1: bzip2
689 2: gzip
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690 3: xz
691- Cypher used for the event packet content. Applied after compression.
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692 0: no encryption
693 1: AES
3bf79539 694- Checksum scheme used for the event packet content. Applied after encryption.
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695 0: no checksum
696 1: md5
697 2: sha1
698 3: crc32
699
6672e9e1 7005.1 Event Packet Header Description
3bf79539 701
fc5425db 702The event packet header layout is indicated by the trace packet.header
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703field. Here is a recommended structure type for the packet header with
704the fields typically expected (although these fields are each optional):
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706struct event_packet_header {
707 uint32_t magic;
3fde5da1 708 uint8_t uuid[16];
3bf79539 709 uint32_t stream_id;
80fd2569 710};
5ba9f198 711
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712trace {
713 ...
714 packet.header := struct event_packet_header;
715};
716
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717If the magic number is not present, tools such as "file" will have no
718mean to discover the file type.
719
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720If the uuid is not present, no validation that the meta-data actually
721corresponds to the stream is performed.
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722
723If the stream_id packet header field is missing, the trace can only
724contain a single stream. Its "id" field can be left out, and its events
725don't need to declare a "stream_id" field.
726
727
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7285.2 Event Packet Context Description
729
730Event packet context example. These are declared within the stream declaration
6672e9e1 731in the meta-data. All these fields are optional. If the packet size field is
6a7c61df 732missing, the whole stream only contains a single packet. If the content
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733size field is missing, the packet is filled (no padding). The content
734and packet sizes include all headers.
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735
736An example event packet context type:
737
80fd2569 738struct event_packet_context {
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739 uint64_t timestamp_begin;
740 uint64_t timestamp_end;
741 uint32_t checksum;
742 uint32_t stream_packet_count;
743 uint32_t events_discarded;
744 uint32_t cpu_id;
745 uint32_t/uint16_t content_size;
746 uint32_t/uint16_t packet_size;
747 uint8_t stream_packet_count_bits; /* Significant counter bits */
748 uint8_t compression_scheme;
749 uint8_t encryption_scheme;
3b0f8e4d 750 uint8_t checksum_scheme;
3bf79539 751};
5ba9f198 752
fcba70d4 753
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7546. Event Structure
755
756The overall structure of an event is:
757
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7581 - Stream Packet Context (as specified by the stream meta-data)
759 2 - Event Header (as specified by the stream meta-data)
760 3 - Stream Event Context (as specified by the stream meta-data)
761 4 - Event Context (as specified by the event meta-data)
762 5 - Event Payload (as specified by the event meta-data)
5ba9f198 763
fdf2bb05 764This structure defines an implicit dynamic scoping, where variants
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765located in inner structures (those with a higher number in the listing
766above) can refer to the fields of outer structures (with lower number in
6c7226e9 767the listing above). See Section 7.3 TSDL Scopes for more detail.
5ba9f198 768
fdf2bb05 7696.1 Event Header
fcba70d4 770
6672e9e1 771Event headers can be described within the meta-data. We hereby propose, as an
fcba70d4
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772example, two types of events headers. Type 1 accommodates streams with less than
77331 event IDs. Type 2 accommodates streams with 31 or more event IDs.
5ba9f198 774
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775One major factor can vary between streams: the number of event IDs assigned to
776a stream. Luckily, this information tends to stay relatively constant (modulo
5ba9f198 777event registration while trace is being recorded), so we can specify different
3bf79539 778representations for streams containing few event IDs and streams containing
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MD
779many event IDs, so we end up representing the event ID and time-stamp as
780densely as possible in each case.
5ba9f198 781
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782The header is extended in the rare occasions where the information cannot be
783represented in the ranges available in the standard event header. They are also
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784used in the rare occasions where the data required for a field could not be
785collected: the flag corresponding to the missing field within the missing_fields
786array is then set to 1.
5ba9f198 787
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788Types uintX_t represent an X-bit unsigned integer, as declared with
789either:
5ba9f198 790
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MD
791 typealias integer { size = X; align = X; signed = false } := uintX_t;
792
793 or
794
795 typealias integer { size = X; align = 1; signed = false } := uintX_t;
5ba9f198 796
fdf2bb05 7976.1.1 Type 1 - Few event IDs
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798
799 - Aligned on 32-bit (or 8-bit if byte-packed, depending on the architecture
800 preference).
5ba9f198 801 - Native architecture byte ordering.
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802 - For "compact" selection
803 - Fixed size: 32 bits.
804 - For "extended" selection
805 - Size depends on the architecture and variant alignment.
5ba9f198 806
80fd2569 807struct event_header_1 {
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808 /*
809 * id: range: 0 - 30.
810 * id 31 is reserved to indicate an extended header.
811 */
a9b83695 812 enum : uint5_t { compact = 0 ... 30, extended = 31 } id;
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813 variant <id> {
814 struct {
815 uint27_t timestamp;
816 } compact;
817 struct {
818 uint32_t id; /* 32-bit event IDs */
819 uint64_t timestamp; /* 64-bit timestamps */
820 } extended;
821 } v;
cb108fea 822} align(32); /* or align(8) */
5ba9f198 823
5ba9f198 824
fdf2bb05 8256.1.2 Type 2 - Many event IDs
5ba9f198 826
fcba70d4 827 - Aligned on 16-bit (or 8-bit if byte-packed, depending on the architecture
5ba9f198 828 preference).
5ba9f198 829 - Native architecture byte ordering.
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830 - For "compact" selection
831 - Size depends on the architecture and variant alignment.
832 - For "extended" selection
833 - Size depends on the architecture and variant alignment.
5ba9f198 834
80fd2569 835struct event_header_2 {
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836 /*
837 * id: range: 0 - 65534.
838 * id 65535 is reserved to indicate an extended header.
839 */
a9b83695 840 enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;
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841 variant <id> {
842 struct {
843 uint32_t timestamp;
844 } compact;
845 struct {
846 uint32_t id; /* 32-bit event IDs */
847 uint64_t timestamp; /* 64-bit timestamps */
848 } extended;
849 } v;
cb108fea 850} align(16); /* or align(8) */
5ba9f198 851
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852
8536.2 Event Context
854
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855The event context contains information relative to the current event.
856The choice and meaning of this information is specified by the TSDL
857stream and event meta-data descriptions. The stream context is applied
858to all events within the stream. The stream context structure follows
859the event header. The event context is applied to specific events. Its
860structure follows the stream context structure.
5ba9f198 861
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862An example of stream-level event context is to save the event payload size with
863each event, or to save the current PID with each event. These are declared
6672e9e1 864within the stream declaration within the meta-data:
5ba9f198 865
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866 stream {
867 ...
6672e9e1 868 event.context := struct {
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MD
869 uint pid;
870 uint16_t payload_size;
6672e9e1 871 };
fcba70d4
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872 };
873
874An example of event-specific event context is to declare a bitmap of missing
875fields, only appended after the stream event context if the extended event
876header is selected. NR_FIELDS is the number of fields within the event (a
877numeric value).
5ba9f198 878
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879 event {
880 context = struct {
881 variant <id> {
882 struct { } compact;
883 struct {
884 uint1_t missing_fields[NR_FIELDS]; /* missing event fields bitmap */
885 } extended;
886 } v;
887 };
888 ...
889 }
5ba9f198
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890
8916.3 Event Payload
892
893An event payload contains fields specific to a given event type. The fields
6672e9e1 894belonging to an event type are described in the event-specific meta-data
5ba9f198
MD
895within a structure type.
896
8976.3.1 Padding
898
899No padding at the end of the event payload. This differs from the ISO/C standard
900for structures, but follows the CTF standard for structures. In a trace, even
901though it makes sense to align the beginning of a structure, it really makes no
902sense to add padding at the end of the structure, because structures are usually
903not followed by a structure of the same type.
904
905This trick can be done by adding a zero-length "end" field at the end of the C
906structures, and by using the offset of this field rather than using sizeof()
3bf79539 907when calculating the size of a structure (see Appendix "A. Helper macros").
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MD
908
9096.3.2 Alignment
910
911The event payload is aligned on the largest alignment required by types
912contained within the payload. (This follows the ISO/C standard for structures)
913
914
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MD
9157. Trace Stream Description Language (TSDL)
916
917The Trace Stream Description Language (TSDL) allows expression of the
918binary trace streams layout in a C99-like Domain Specific Language
919(DSL).
920
921
6672e9e1 9227.1 Meta-data
6c7226e9
MD
923
924The trace stream layout description is located in the trace meta-data.
925The meta-data is itself located in a stream identified by its name:
926"metadata".
5ba9f198 927
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928The meta-data description can be expressed in two different formats:
929text-only and packet-based. The text-only description facilitates
930generation of meta-data and provides a convenient way to enter the
931meta-data information by hand. The packet-based meta-data provides the
932CTF stream packet facilities (checksumming, compression, encryption,
933network-readiness) for meta-data stream generated and transported by a
934tracer.
935
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936The text-only meta-data file is a plain-text TSDL description. This file
937must begin with the following characters to identify the file as a CTF
9486a18c 938TSDL text-based metadata file (without the double-quotes) :
1b4d35eb 939
ec2b4db8 940"/* CTF"
1b4d35eb 941
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942It must be followed by a space, and the version of the specification
943followed by the CTF trace, e.g.:
944
945" 1.8"
946
947These characters allow automated discovery of file type and CTF
948specification version. They are interpreted as a the beginning of a
949comment by the TSDL metadata parser. The comment can be continued to
950contain extra commented characters before it is closed.
6672e9e1
MD
951
952The packet-based meta-data is made of "meta-data packets", which each
953start with a meta-data packet header. The packet-based meta-data
954description is detected by reading the magic number "0x75D11D57" at the
955beginning of the file. This magic number is also used to detect the
956endianness of the architecture by trying to read the CTF magic number
957and its counterpart in reversed endianness. The events within the
958meta-data stream have no event header nor event context. Each event only
5ae2352d 959contains a "sequence" payload, which is a sequence of bits using the
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960"trace.packet.header.content_size" field as a placeholder for its length
961(the packet header size should be substracted). The formatting of this
962sequence of bits is a plain-text representation of the TSDL description.
963Each meta-data packet start with a special packet header, specific to
964the meta-data stream, which contains, exactly:
6672e9e1
MD
965
966struct metadata_packet_header {
2daeaa3a 967 uint32_t magic; /* 0x75D11D57 */
3fde5da1 968 uint8_t uuid[16]; /* Unique Universal Identifier */
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969 uint32_t checksum; /* 0 if unused */
970 uint32_t content_size; /* in bits */
971 uint32_t packet_size; /* in bits */
972 uint8_t compression_scheme; /* 0 if unused */
973 uint8_t encryption_scheme; /* 0 if unused */
974 uint8_t checksum_scheme; /* 0 if unused */
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MD
975 uint8_t major; /* CTF spec version major number */
976 uint8_t minor; /* CTF spec version minor number */
6672e9e1
MD
977};
978
979The packet-based meta-data can be converted to a text-only meta-data by
980concatenating all the strings in contains.
4fafe1ad 981
6672e9e1
MD
982In the textual representation of the meta-data, the text contained
983within "/*" and "*/", as well as within "//" and end of line, are
984treated as comments. Boolean values can be represented as true, TRUE,
985or 1 for true, and false, FALSE, or 0 for false. Within the string-based
986meta-data description, the trace UUID is represented as a string of
987hexadecimal digits and dashes "-". In the event packet header, the trace
988UUID is represented as an array of bytes.
fcba70d4 989
fdf2bb05 990
6c7226e9 9917.2 Declaration vs Definition
fdf2bb05
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992
993A declaration associates a layout to a type, without specifying where
994this type is located in the event structure hierarchy (see Section 6).
995This therefore includes typedef, typealias, as well as all type
996specifiers. In certain circumstances (typedef, structure field and
997variant field), a declaration is followed by a declarator, which specify
998the newly defined type name (for typedef), or the field name (for
999declarations located within structure and variants). Array and sequence,
1000declared with square brackets ("[" "]"), are part of the declarator,
a9b83695 1001similarly to C99. The enumeration base type is specified by
6c7226e9 1002": enum_base", which is part of the type specifier. The variant tag
a9b83695 1003name, specified between "<" ">", is also part of the type specifier.
fdf2bb05
MD
1004
1005A definition associates a type to a location in the event structure
b9606a77
MD
1006hierarchy (see Section 6). This association is denoted by ":=", as shown
1007in Section 7.3.
fdf2bb05
MD
1008
1009
6c7226e9 10107.3 TSDL Scopes
fdf2bb05 1011
37ab95c3
MD
1012TSDL uses three different types of scoping: a lexical scope is used for
1013declarations and type definitions, and static and dynamic scopes are
1014used for variants references to tag fields (with relative and absolute
1015path lookups) and for sequence references to length fields.
fdf2bb05 1016
6c7226e9 10177.3.1 Lexical Scope
fdf2bb05 1018
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MD
1019Each of "trace", "stream", "event", "struct" and "variant" have their own
1020nestable declaration scope, within which types can be declared using "typedef"
fdf2bb05 1021and "typealias". A root declaration scope also contains all declarations
7d9d7e92 1022located outside of any of the aforementioned declarations. An inner
fdf2bb05 1023declaration scope can refer to type declared within its container
7d9d7e92
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1024lexical scope prior to the inner declaration scope. Redefinition of a
1025typedef or typealias is not valid, although hiding an upper scope
fdf2bb05
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1026typedef or typealias is allowed within a sub-scope.
1027
37ab95c3 10287.3.2 Static and Dynamic Scopes
fdf2bb05 1029
37ab95c3
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1030A local static scope consists in the scope generated by the declaration
1031of fields within a compound type. A static scope is a local static scope
1032augmented with the nested sub-static-scopes it contains.
1033
1034A dynamic scope consists in the static scope augmented with the
7d9d7e92 1035implicit event structure definition hierarchy presented at Section 6.
fdf2bb05 1036
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1037Multiple declarations of the same field name within a local static scope
1038is not valid. It is however valid to re-use the same field name in
1039different local scopes.
1040
1041Nested static and dynamic scopes form lookup paths. These are used for
1042variant tag and sequence length references. They are used at the variant
1043and sequence definition site to look up the location of the tag field
1044associated with a variant, and to lookup up the location of the length
1045field associated with a sequence.
1046
1047Variants and sequences can refer to a tag field either using a relative
1048path or an absolute path. The relative path starts with "." to ensure
1049there are no conflicts with dynamic scope names. It is relative to the
1050scope in which the variant or sequence performing the lookup is located.
1051Relative paths are only allowed to lookup within the same static scope,
1052which includes its nested static scopes. Lookups targeting parent static
1053scopes need to be performed with an absolute path.
1054
1055Absolute path lookups use the full path including the dynamic scope
1056followed by a "." and then the static scope. Therefore, variants (or
1057sequences) in lower levels in the dynamic scope (e.g. event context) can
1058refer to a tag (or length) field located in upper levels (e.g. in the
1059event header) by specifying, in this case, the associated tag with
1060<stream.event.header.field_name>. This allows, for instance, the event
1061context to define a variant referring to the "id" field of the event
1062header as selector.
1063
284724ae 1064The dynamic scope prefixes are thus:
fdf2bb05 1065
e0d9e2c7 1066 - Trace Packet Header: <trace.packet.header. >,
7d9d7e92
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1067 - Stream Packet Context: <stream.packet.context. >,
1068 - Event Header: <stream.event.header. >,
1069 - Stream Event Context: <stream.event.context. >,
1070 - Event Context: <event.context. >,
1071 - Event Payload: <event.fields. >.
fdf2bb05 1072
37ab95c3
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1073
1074The target dynamic scope must be specified explicitly when referring to
1075a field outside of the static scope (absolute scope reference).
1076References to fields within the static scope (including local static
1077scopes and nested static scopes) can be referenced by using a relative
1078reference (starting with ".").
1079
1080As a matter of convenience, the leading "." in relative paths can be
1081omitted. In case of conflict between relative and dynamic paths, the
1082relative path is preferred. It is recommended to use the "." prefix for
1083relative paths to ensure no path name conflict can occur.
fdf2bb05 1084
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1085The information available in the dynamic scopes can be thought of as the
1086current tracing context. At trace production, information about the
1087current context is saved into the specified scope field levels. At trace
1088consumption, for each event, the current trace context is therefore
1089readable by accessing the upper dynamic scopes.
1090
fdf2bb05 1091
6c7226e9 10927.4 TSDL Examples
d285084f 1093
6672e9e1 1094The grammar representing the TSDL meta-data is presented in Appendix C.
7df6b93a 1095TSDL Grammar. This section presents a rather lighter reading that
6672e9e1 1096consists in examples of TSDL meta-data, with template values.
969f30c0 1097
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1098The stream "id" can be left out if there is only one stream in the
1099trace. The event "id" field can be left out if there is only one event
1100in a stream.
1101
5ba9f198 1102trace {
fdf2bb05 1103 major = value; /* Trace format version */
5ba9f198 1104 minor = value;
fdf2bb05 1105 uuid = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"; /* Trace UUID */
58997e9e 1106 byte_order = be OR le; /* Endianness (required) */
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1107 packet.header := struct {
1108 uint32_t magic;
3fde5da1 1109 uint8_t uuid[16];
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1110 uint32_t stream_id;
1111 };
3bf79539 1112};
5ba9f198 1113
3bf79539
MD
1114stream {
1115 id = stream_id;
fdf2bb05 1116 /* Type 1 - Few event IDs; Type 2 - Many event IDs. See section 6.1. */
4fa992a5
MD
1117 event.header := event_header_1 OR event_header_2;
1118 event.context := struct {
77a98c82 1119 ...
3bf79539 1120 };
4fa992a5 1121 packet.context := struct {
77a98c82 1122 ...
3bf79539
MD
1123 };
1124};
5ba9f198
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1125
1126event {
3d13ef1a 1127 name = event_name;
3bf79539 1128 id = value; /* Numeric identifier within the stream */
67f02e24 1129 stream_id = stream_id;
4fa992a5 1130 context := struct {
fcba70d4
MD
1131 ...
1132 };
4fa992a5 1133 fields := struct {
80fd2569
MD
1134 ...
1135 };
3bf79539 1136};
5ba9f198
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1137
1138/* More detail on types in section 4. Types */
1139
3d13ef1a
MD
1140/*
1141 * Named types:
1142 *
4fa992a5 1143 * Type declarations behave similarly to the C standard.
3d13ef1a
MD
1144 */
1145
80af8ac6 1146typedef aliased_type_specifiers new_type_declarators;
2152348f 1147
3d13ef1a 1148/* e.g.: typedef struct example new_type_name[10]; */
80fd2569 1149
4fa992a5
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1150/*
1151 * typealias
1152 *
1153 * The "typealias" declaration can be used to give a name (including
80af8ac6
MD
1154 * pointer declarator specifier) to a type. It should also be used to
1155 * map basic C types (float, int, unsigned long, ...) to a CTF type.
1156 * Typealias is a superset of "typedef": it also allows assignment of a
38b8da21 1157 * simple variable identifier to a type.
4fa992a5
MD
1158 */
1159
1160typealias type_class {
80fd2569 1161 ...
38b8da21 1162} := type_specifiers type_declarator;
2152348f 1163
3d13ef1a
MD
1164/*
1165 * e.g.:
4fa992a5 1166 * typealias integer {
3d13ef1a
MD
1167 * size = 32;
1168 * align = 32;
1169 * signed = false;
38b8da21 1170 * } := struct page *;
359894ac
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1171 *
1172 * typealias integer {
1173 * size = 32;
1174 * align = 32;
1175 * signed = true;
38b8da21 1176 * } := int;
3d13ef1a 1177 */
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1178
1179struct name {
3bf79539
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1180 ...
1181};
5ba9f198 1182
fcba70d4
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1183variant name {
1184 ...
1185};
1186
a9b83695 1187enum name : integer_type {
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1188 ...
1189};
1190
2152348f 1191
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1192/*
1193 * Unnamed types, contained within compound type fields, typedef or typealias.
1194 */
2152348f 1195
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1196struct {
1197 ...
2152348f 1198}
5ba9f198 1199
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1200struct {
1201 ...
1202} align(value)
1203
fcba70d4
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1204variant {
1205 ...
1206}
1207
a9b83695 1208enum : integer_type {
80fd2569 1209 ...
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1210}
1211
1212typedef type new_type[length];
3bf79539 1213
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1214struct {
1215 type field_name[length];
1216}
1217
1218typedef type new_type[length_type];
1219
1220struct {
1221 type field_name[length_type];
1222}
1223
1224integer {
80fd2569 1225 ...
2152348f 1226}
3bf79539 1227
2152348f 1228floating_point {
80fd2569 1229 ...
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MD
1230}
1231
1232struct {
1233 integer_type field_name:size; /* GNU/C bitfield */
1234}
1235
1236struct {
1237 string field_name;
1238}
3bf79539 1239
fcba70d4 1240
3bf79539 1241A. Helper macros
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1242
1243The two following macros keep track of the size of a GNU/C structure without
1244padding at the end by placing HEADER_END as the last field. A one byte end field
1245is used for C90 compatibility (C99 flexible arrays could be used here). Note
1246that this does not affect the effective structure size, which should always be
1247calculated with the header_sizeof() helper.
1248
1249#define HEADER_END char end_field
1250#define header_sizeof(type) offsetof(typeof(type), end_field)
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1251
1252
1253B. Stream Header Rationale
1254
1255An event stream is divided in contiguous event packets of variable size. These
1256subdivisions allow the trace analyzer to perform a fast binary search by time
1257within the stream (typically requiring to index only the event packet headers)
1258without reading the whole stream. These subdivisions have a variable size to
1259eliminate the need to transfer the event packet padding when partially filled
1260event packets must be sent when streaming a trace for live viewing/analysis.
1261An event packet can contain a certain amount of padding at the end. Dividing
1262streams into event packets is also useful for network streaming over UDP and
1263flight recorder mode tracing (a whole event packet can be swapped out of the
1264buffer atomically for reading).
1265
1266The stream header is repeated at the beginning of each event packet to allow
1267flexibility in terms of:
1268
1269 - streaming support,
1270 - allowing arbitrary buffers to be discarded without making the trace
1271 unreadable,
1272 - allow UDP packet loss handling by either dealing with missing event packet
1273 or asking for re-transmission.
1274 - transparently support flight recorder mode,
1275 - transparently support crash dump.
1276
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1277
1278C. TSDL Grammar
fcba70d4 1279
4fa992a5 1280/*
6c7226e9 1281 * Common Trace Format (CTF) Trace Stream Description Language (TSDL) Grammar.
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1282 *
1283 * Inspired from the C99 grammar:
1284 * http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf (Annex A)
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1285 * and c++1x grammar (draft)
1286 * http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3291.pdf (Annex A)
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1287 *
1288 * Specialized for CTF needs by including only constant and declarations from
1289 * C99 (excluding function declarations), and by adding support for variants,
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1290 * sequences and CTF-specific specifiers. Enumeration container types
1291 * semantic is inspired from c++1x enum-base.
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1292 */
1293
12941) Lexical grammar
1295
12961.1) Lexical elements
1297
1298token:
1299 keyword
1300 identifier
1301 constant
1302 string-literal
1303 punctuator
1304
13051.2) Keywords
1306
1307keyword: is one of
1308
ec4404a7 1309align
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1310const
1311char
1312double
1313enum
1314event
1315floating_point
1316float
1317integer
1318int
1319long
1320short
1321signed
1322stream
1323string
1324struct
1325trace
3e1e1a78 1326typealias
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MD
1327typedef
1328unsigned
1329variant
1330void
1331_Bool
1332_Complex
1333_Imaginary
1334
1335
13361.3) Identifiers
1337
1338identifier:
1339 identifier-nondigit
1340 identifier identifier-nondigit
1341 identifier digit
1342
1343identifier-nondigit:
1344 nondigit
1345 universal-character-name
1346 any other implementation-defined characters
1347
1348nondigit:
1349 _
1350 [a-zA-Z] /* regular expression */
1351
1352digit:
1353 [0-9] /* regular expression */
1354
13551.4) Universal character names
1356
1357universal-character-name:
1358 \u hex-quad
1359 \U hex-quad hex-quad
1360
1361hex-quad:
1362 hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
1363
13641.5) Constants
1365
1366constant:
1367 integer-constant
1368 enumeration-constant
1369 character-constant
1370
1371integer-constant:
1372 decimal-constant integer-suffix-opt
1373 octal-constant integer-suffix-opt
1374 hexadecimal-constant integer-suffix-opt
1375
1376decimal-constant:
1377 nonzero-digit
1378 decimal-constant digit
1379
1380octal-constant:
1381 0
1382 octal-constant octal-digit
1383
1384hexadecimal-constant:
1385 hexadecimal-prefix hexadecimal-digit
1386 hexadecimal-constant hexadecimal-digit
1387
1388hexadecimal-prefix:
1389 0x
1390 0X
1391
1392nonzero-digit:
1393 [1-9]
1394
1395integer-suffix:
1396 unsigned-suffix long-suffix-opt
1397 unsigned-suffix long-long-suffix
1398 long-suffix unsigned-suffix-opt
1399 long-long-suffix unsigned-suffix-opt
1400
1401unsigned-suffix:
1402 u
1403 U
1404
1405long-suffix:
1406 l
1407 L
1408
1409long-long-suffix:
1410 ll
1411 LL
1412
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MD
1413enumeration-constant:
1414 identifier
1415 string-literal
1416
1417character-constant:
1418 ' c-char-sequence '
1419 L' c-char-sequence '
1420
1421c-char-sequence:
1422 c-char
1423 c-char-sequence c-char
1424
1425c-char:
1426 any member of source charset except single-quote ('), backslash
1427 (\), or new-line character.
1428 escape-sequence
1429
1430escape-sequence:
1431 simple-escape-sequence
1432 octal-escape-sequence
1433 hexadecimal-escape-sequence
1434 universal-character-name
1435
1436simple-escape-sequence: one of
1437 \' \" \? \\ \a \b \f \n \r \t \v
1438
1439octal-escape-sequence:
1440 \ octal-digit
1441 \ octal-digit octal-digit
1442 \ octal-digit octal-digit octal-digit
1443
1444hexadecimal-escape-sequence:
1445 \x hexadecimal-digit
1446 hexadecimal-escape-sequence hexadecimal-digit
1447
14481.6) String literals
1449
1450string-literal:
1451 " s-char-sequence-opt "
1452 L" s-char-sequence-opt "
1453
1454s-char-sequence:
1455 s-char
1456 s-char-sequence s-char
1457
1458s-char:
1459 any member of source charset except double-quote ("), backslash
1460 (\), or new-line character.
1461 escape-sequence
1462
14631.7) Punctuators
1464
1465punctuator: one of
1466 [ ] ( ) { } . -> * + - < > : ; ... = ,
1467
1468
14692) Phrase structure grammar
1470
1471primary-expression:
1472 identifier
1473 constant
1474 string-literal
1475 ( unary-expression )
1476
1477postfix-expression:
1478 primary-expression
1479 postfix-expression [ unary-expression ]
1480 postfix-expression . identifier
1481 postfix-expressoin -> identifier
1482
1483unary-expression:
1484 postfix-expression
1485 unary-operator postfix-expression
1486
1487unary-operator: one of
1488 + -
1489
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1490assignment-operator:
1491 =
1492
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1493type-assignment-operator:
1494 :=
1495
4fa992a5 1496constant-expression-range:
73d61ac3 1497 unary-expression ... unary-expression
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1498
14992.2) Declarations:
1500
1501declaration:
689e04b4 1502 declaration-specifiers declarator-list-opt ;
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1503 ctf-specifier ;
1504
1505declaration-specifiers:
689e04b4 1506 storage-class-specifier declaration-specifiers-opt
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1507 type-specifier declaration-specifiers-opt
1508 type-qualifier declaration-specifiers-opt
1509
1510declarator-list:
1511 declarator
1512 declarator-list , declarator
1513
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1514abstract-declarator-list:
1515 abstract-declarator
1516 abstract-declarator-list , abstract-declarator
1517
4fa992a5
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1518storage-class-specifier:
1519 typedef
1520
1521type-specifier:
1522 void
1523 char
1524 short
1525 int
1526 long
1527 float
1528 double
1529 signed
1530 unsigned
1531 _Bool
1532 _Complex
cfdd51ec 1533 _Imaginary
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1534 struct-specifier
1535 variant-specifier
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1536 enum-specifier
1537 typedef-name
1538 ctf-type-specifier
1539
ec4404a7 1540align-attribute:
73d61ac3 1541 align ( unary-expression )
ec4404a7 1542
4fa992a5 1543struct-specifier:
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MD
1544 struct identifier-opt { struct-or-variant-declaration-list-opt } align-attribute-opt
1545 struct identifier align-attribute-opt
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1546
1547struct-or-variant-declaration-list:
1548 struct-or-variant-declaration
1549 struct-or-variant-declaration-list struct-or-variant-declaration
1550
1551struct-or-variant-declaration:
1552 specifier-qualifier-list struct-or-variant-declarator-list ;
eacb16d1 1553 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list ;
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1554 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list ;
1555 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list ;
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1556
1557specifier-qualifier-list:
1558 type-specifier specifier-qualifier-list-opt
1559 type-qualifier specifier-qualifier-list-opt
1560
1561struct-or-variant-declarator-list:
1562 struct-or-variant-declarator
1563 struct-or-variant-declarator-list , struct-or-variant-declarator
1564
1565struct-or-variant-declarator:
1566 declarator
73d61ac3 1567 declarator-opt : unary-expression
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1568
1569variant-specifier:
1570 variant identifier-opt variant-tag-opt { struct-or-variant-declaration-list }
1571 variant identifier variant-tag
1572
1573variant-tag:
37ab95c3 1574 < unary-expression >
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1575
1576enum-specifier:
1577 enum identifier-opt { enumerator-list }
1578 enum identifier-opt { enumerator-list , }
1579 enum identifier
a9b83695
MD
1580 enum identifier-opt : declaration-specifiers { enumerator-list }
1581 enum identifier-opt : declaration-specifiers { enumerator-list , }
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1582
1583enumerator-list:
1584 enumerator
1585 enumerator-list , enumerator
1586
1587enumerator:
1588 enumeration-constant
8d2d41f7
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1589 enumeration-constant assignment-operator unary-expression
1590 enumeration-constant assignment-operator constant-expression-range
4fa992a5
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1591
1592type-qualifier:
1593 const
1594
1595declarator:
1596 pointer-opt direct-declarator
1597
1598direct-declarator:
1599 identifier
1600 ( declarator )
1ab22b2a 1601 direct-declarator [ unary-expression ]
4fa992a5 1602
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1603abstract-declarator:
1604 pointer-opt direct-abstract-declarator
1605
1606direct-abstract-declarator:
1607 identifier-opt
1608 ( abstract-declarator )
1ab22b2a 1609 direct-abstract-declarator [ unary-expression ]
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1610 direct-abstract-declarator [ ]
1611
4fa992a5 1612pointer:
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1613 * type-qualifier-list-opt
1614 * type-qualifier-list-opt pointer
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1615
1616type-qualifier-list:
1617 type-qualifier
1618 type-qualifier-list type-qualifier
1619
4fa992a5
MD
1620typedef-name:
1621 identifier
1622
16232.3) CTF-specific declarations
1624
1625ctf-specifier:
1626 event { ctf-assignment-expression-list-opt }
1627 stream { ctf-assignment-expression-list-opt }
1628 trace { ctf-assignment-expression-list-opt }
b12919a5
MD
1629 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1630 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
4fa992a5
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1631
1632ctf-type-specifier:
1633 floating_point { ctf-assignment-expression-list-opt }
1634 integer { ctf-assignment-expression-list-opt }
1635 string { ctf-assignment-expression-list-opt }
7609d3c7 1636 string
4fa992a5
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1637
1638ctf-assignment-expression-list:
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1639 ctf-assignment-expression ;
1640 ctf-assignment-expression-list ctf-assignment-expression ;
4fa992a5
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1641
1642ctf-assignment-expression:
1643 unary-expression assignment-operator unary-expression
1644 unary-expression type-assignment-operator type-specifier
eacb16d1 1645 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list
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1646 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1647 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
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