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[ctf.git] / common-trace-format-specification.txt
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f5cb0e57 1Common Trace Format (CTF) Specification (v1.8.2)
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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
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44 4.2 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
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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
0b174d87 57 6.2 Stream Event Context and Event Context
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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
beabf088 67 7.4 TSDL Examples
2fa70eba 688. Clocks
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69
70
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711. Preliminary definitions
72
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73 - Event Trace: An ordered sequence of events.
74 - Event Stream: An ordered sequence of events, containing a subset of the
75 trace event types.
76 - Event Packet: A sequence of physically contiguous events within an event
77 stream.
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78 - Event: This is the basic entry in a trace. (aka: a trace record).
79 - An event identifier (ID) relates to the class (a type) of event within
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80 an event stream.
81 e.g. event: irq_entry.
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82 - An event (or event record) relates to a specific instance of an event
83 class.
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84 e.g. event: irq_entry, at time X, on CPU Y
85 - Source Architecture: Architecture writing the trace.
86 - Reader Architecture: Architecture reading the trace.
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87
88
892. High-level representation of a trace
90
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91A trace is divided into multiple event streams. Each event stream contains a
92subset of the trace event types.
5ba9f198 93
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94The final output of the trace, after its generation and optional transport over
95the network, is expected to be either on permanent or temporary storage in a
96virtual file system. Because each event stream is appended to while a trace is
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97being recorded, each is associated with a distinct set of files for
98output. Therefore, a stored trace can be represented as a directory
99containing zero, one or more files per stream.
5ba9f198 100
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101Meta-data description associated with the trace contains information on
102trace event types expressed in the Trace Stream Description Language
103(TSDL). This language describes:
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104
105- Trace version.
106- Types available.
6672e9e1 107- Per-trace event header description.
3bf79539 108- Per-stream event header description.
6672e9e1 109- Per-stream event context description.
5ba9f198 110- Per-event
3bf79539 111 - Event type to stream mapping.
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112 - Event type to name mapping.
113 - Event type to ID mapping.
6672e9e1 114 - Event context description.
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115 - Event fields description.
116
117
3bf79539 1183. Event stream
5ba9f198 119
6672e9e1 120An event stream can be divided into contiguous event packets of variable
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121size. An event packet can contain a certain amount of padding at the
122end. The stream header is repeated at the beginning of each event
123packet. The rationale for the event stream design choices is explained
124in Appendix B. Stream Header Rationale.
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
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168The base offset used for field alignment is the start of the packet
169containing the field. For instance, a field aligned on 32-bit needs to
170be at an offset multiple of 32-bit from the start of the packet that
171contains it.
172
6672e9e1 173TSDL meta-data attribute representation of a specific alignment:
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174
175 align = value; /* value in bits */
176
1774.1.3 Byte order
178
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179By default, byte order of a basic type is the byte order described in
180the trace description. It can be overridden by specifying a
181"byte_order" attribute for a basic type. Typical use-case is to specify
182the network byte order (big endian: "be") to save data captured from the
183network into the trace without conversion.
5ba9f198 184
6672e9e1 185TSDL meta-data representation:
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186
187 byte_order = native OR network OR be OR le; /* network and be are aliases */
188
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189The "native" keyword selects the byte order described in the trace
190description. The "network" byte order is an alias for big endian.
191
7e58b8bf 192Even though the trace description section is not per se a type, for sake
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193of clarity, it should be noted that "native" and "network" byte orders
194are only allowed within type declaration. The byte_order specified in
195the trace description section only accepts "be" or "le" values.
7e58b8bf 196
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1974.1.4 Size
198
199Type size, in bits, for integers and floats is that returned by "sizeof()" in C
200multiplied by CHAR_BIT.
201We require the size of "char" and "unsigned char" types (CHAR_BIT) to be fixed
202to 8 bits for cross-endianness compatibility.
203
6672e9e1 204TSDL meta-data representation:
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205
206 size = value; (value is in bits)
207
2084.1.5 Integers
209
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210Signed integers are represented in two-complement. Integer alignment,
211size, signedness and byte ordering are defined in the TSDL meta-data.
212Integers aligned on byte size (8-bit) and with length multiple of byte
213size (8-bit) correspond to the C99 standard integers. In addition,
214integers with alignment and/or size that are _not_ a multiple of the
215byte size are permitted; these correspond to the C99 standard bitfields,
216with the added specification that the CTF integer bitfields have a fixed
217binary representation. A MIT-licensed reference implementation of the
218CTF portable bitfields is available at:
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219
220 http://git.efficios.com/?p=babeltrace.git;a=blob;f=include/babeltrace/bitfield.h
221
222Binary representation of integers:
223
224- On little and big endian:
225 - Within a byte, high bits correspond to an integer high bits, and low bits
226 correspond to low bits.
227- On little endian:
228 - Integer across multiple bytes are placed from the less significant to the
229 most significant.
230 - Consecutive integers are placed from lower bits to higher bits (even within
231 a byte).
232- On big endian:
233 - Integer across multiple bytes are placed from the most significant to the
234 less significant.
235 - Consecutive integers are placed from higher bits to lower bits (even within
236 a byte).
237
238This binary representation is derived from the bitfield implementation in GCC
239for little and big endian. However, contrary to what GCC does, integers can
6672e9e1 240cross units boundaries (no padding is required). Padding can be explicitly
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241added (see 4.1.6 GNU/C bitfields) to follow the GCC layout if needed.
242
6672e9e1 243TSDL meta-data representation:
5ba9f198 244
80fd2569 245 integer {
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246 signed = true OR false; /* default false */
247 byte_order = native OR network OR be OR le; /* default native */
248 size = value; /* value in bits, no default */
249 align = value; /* value in bits */
56b77c06 250 /* based used for pretty-printing output, default: decimal. */
b46cfbf6 251 base = decimal OR dec OR d OR i OR u OR 10 OR hexadecimal OR hex OR x OR X OR p OR 16
56b77c06 252 OR octal OR oct OR o OR 8 OR binary OR b OR 2;
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253 /* character encoding, default: none */
254 encoding = none or UTF8 or ASCII;
2152348f 255 }
5ba9f198 256
80fd2569 257Example of type inheritance (creation of a uint32_t named type):
5ba9f198 258
359894ac 259typealias integer {
9e4e34e9 260 size = 32;
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261 signed = false;
262 align = 32;
38b8da21 263} := uint32_t;
5ba9f198 264
80fd2569 265Definition of a named 5-bit signed bitfield:
5ba9f198 266
359894ac 267typealias integer {
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268 size = 5;
269 signed = true;
270 align = 1;
38b8da21 271} := int5_t;
5ba9f198 272
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273The character encoding field can be used to specify that the integer
274must be printed as a text character when read. e.g.:
275
276typealias integer {
277 size = 8;
278 align = 8;
279 signed = false;
280 encoding = UTF8;
281} := utf_char;
282
283
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2844.1.6 GNU/C bitfields
285
286The GNU/C bitfields follow closely the integer representation, with a
287particularity on alignment: if a bitfield cannot fit in the current unit, the
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288unit is padded and the bitfield starts at the following unit. The unit size is
289defined by the size of the type "unit_type".
5ba9f198 290
6672e9e1 291TSDL meta-data representation:
80fd2569 292
d674f4b8 293 unit_type name:size;
80fd2569 294
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295As an example, the following structure declared in C compiled by GCC:
296
297struct example {
298 short a:12;
299 short b:5;
300};
301
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302The example structure is aligned on the largest element (short). The second
303bitfield would be aligned on the next unit boundary, because it would not fit in
304the current unit.
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305
3064.1.7 Floating point
307
6672e9e1 308The floating point values byte ordering is defined in the TSDL meta-data.
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309
310Floating point values follow the IEEE 754-2008 standard interchange formats.
311Description of the floating point values include the exponent and mantissa size
312in bits. Some requirements are imposed on the floating point values:
313
314- FLT_RADIX must be 2.
315- mant_dig is the number of digits represented in the mantissa. It is specified
316 by the ISO C99 standard, section 5.2.4, as FLT_MANT_DIG, DBL_MANT_DIG and
317 LDBL_MANT_DIG as defined by <float.h>.
318- exp_dig is the number of digits represented in the exponent. Given that
319 mant_dig is one bit more than its actual size in bits (leading 1 is not
320 needed) and also given that the sign bit always takes one bit, exp_dig can be
321 specified as:
322
323 - sizeof(float) * CHAR_BIT - FLT_MANT_DIG
324 - sizeof(double) * CHAR_BIT - DBL_MANT_DIG
325 - sizeof(long double) * CHAR_BIT - LDBL_MANT_DIG
326
6672e9e1 327TSDL meta-data representation:
5ba9f198 328
80fd2569 329floating_point {
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330 exp_dig = value;
331 mant_dig = value;
332 byte_order = native OR network OR be OR le;
333 align = value;
2152348f 334}
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335
336Example of type inheritance:
337
359894ac 338typealias floating_point {
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339 exp_dig = 8; /* sizeof(float) * CHAR_BIT - FLT_MANT_DIG */
340 mant_dig = 24; /* FLT_MANT_DIG */
341 byte_order = native;
ec4404a7 342 align = 32;
38b8da21 343} := float;
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344
345TODO: define NaN, +inf, -inf behavior.
346
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347Bit-packed, byte-packed or larger alignments can be used for floating
348point values, similarly to integers.
349
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3504.1.8 Enumerations
351
352Enumerations are a mapping between an integer type and a table of strings. The
353numerical representation of the enumeration follows the integer type specified
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354by the meta-data. The enumeration mapping table is detailed in the enumeration
355description within the meta-data. The mapping table maps inclusive value
356ranges (or single values) to strings. Instead of being limited to simple
3bf79539 357"value -> string" mappings, these enumerations map
80fd2569 358"[ start_value ... end_value ] -> string", which map inclusive ranges of
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359values to strings. An enumeration from the C language can be represented in
360this format by having the same start_value and end_value for each element, which
361is in fact a range of size 1. This single-value range is supported without
4767a9e7 362repeating the start and end values with the value = string declaration.
80fd2569 363
a9b83695 364enum name : integer_type {
359894ac 365 somestring = start_value1 ... end_value1,
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366 "other string" = start_value2 ... end_value2,
367 yet_another_string, /* will be assigned to end_value2 + 1 */
368 "some other string" = value,
369 ...
370};
371
372If the values are omitted, the enumeration starts at 0 and increment of 1 for
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373each entry. An entry with omitted value that follows a range entry takes
374as value the end_value of the previous range + 1:
80fd2569 375
a9b83695 376enum name : unsigned int {
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377 ZERO,
378 ONE,
379 TWO,
380 TEN = 10,
381 ELEVEN,
3bf79539 382};
5ba9f198 383
80fd2569 384Overlapping ranges within a single enumeration are implementation defined.
5ba9f198 385
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386A nameless enumeration can be declared as a field type or as part of a typedef:
387
a9b83695 388enum : integer_type {
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389 ...
390}
391
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392Enumerations omitting the container type ": integer_type" use the "int"
393type (for compatibility with C99). The "int" type must be previously
394declared. E.g.:
395
82cbdb16 396typealias integer { size = 32; align = 32; signed = true; } := int;
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397
398enum {
399 ...
400}
401
1fad7a85 402
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4034.2 Compound types
404
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405Compound are aggregation of type declarations. Compound types include
406structures, variant, arrays, sequences, and strings.
407
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4084.2.1 Structures
409
410Structures are aligned on the largest alignment required by basic types
411contained within the structure. (This follows the ISO/C standard for structures)
412
6672e9e1 413TSDL meta-data representation of a named structure:
5ba9f198 414
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415struct name {
416 field_type field_name;
417 field_type field_name;
418 ...
419};
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420
421Example:
422
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423struct example {
424 integer { /* Nameless type */
425 size = 16;
426 signed = true;
427 align = 16;
428 } first_field_name;
6672e9e1 429 uint64_t second_field_name; /* Named type declared in the meta-data */
3bf79539 430};
5ba9f198 431
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432The fields are placed in a sequence next to each other. They each
433possess a field name, which is a unique identifier within the structure.
434The identifier is not allowed to use any reserved keyword
435(see Section C.1.2). Replacing reserved keywords with
70375f92 436underscore-prefixed field names is recommended. Fields starting with an
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437underscore should have their leading underscore removed by the CTF trace
438readers.
5ba9f198 439
2152348f 440A nameless structure can be declared as a field type or as part of a typedef:
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441
442struct {
443 ...
2152348f 444}
80fd2569 445
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446Alignment for a structure compound type can be forced to a minimum value
447by adding an "align" specifier after the declaration of a structure
448body. This attribute is read as: align(value). The value is specified in
449bits. The structure will be aligned on the maximum value between this
450attribute and the alignment required by the basic types contained within
451the structure. e.g.
452
453struct {
454 ...
455} align(32)
456
77a98c82 4574.2.2 Variants (Discriminated/Tagged Unions)
fcba70d4 458
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459A CTF variant is a selection between different types. A CTF variant must
460always be defined within the scope of a structure or within fields
461contained within a structure (defined recursively). A "tag" enumeration
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462field must appear in either the same static scope, prior to the variant
463field (in field declaration order), in an upper static scope , or in an
464upper dynamic scope (see Section 7.3.2). The type selection is indicated
465by the mapping from the enumeration value to the string used as variant
466type selector. The field to use as tag is specified by the "tag_field",
467specified between "< >" after the "variant" keyword for unnamed
468variants, and after "variant name" for named variants.
fcba70d4 469
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470The alignment of the variant is the alignment of the type as selected by
471the tag value for the specific instance of the variant. The size of the
472variant is the size as selected by the tag value for the specific
473instance of the variant.
474
475The alignment of the type containing the variant is independent of the
476variant alignment. For instance, if a structure contains two fields, a
47732-bit integer, aligned on 32 bits, and a variant, which contains two
478choices: either a 32-bit field, aligned on 32 bits, or a 64-bit field,
479aligned on 64 bits, the alignment of the outmost structure will be
48032-bit (the alignment of its largest field, disregarding the alignment
481of the variant). The alignment of the variant will depend on the
482selector: if the variant's 32-bit field is selected, its alignment will
483be 32-bit, or 64-bit otherwise. It is important to note that variants
484are specifically tailored for compactness in a stream. Therefore, the
485relative offsets of compound type fields can vary depending on
486the offset at which the compound type starts if it contains a variant
487that itself contains a type with alignment larger than the largest field
488contained within the compound type. This is caused by the fact that the
489compound type may contain the enumeration that select the variant's
490choice, and therefore the alignment to be applied to the compound type
491cannot be determined before encountering the enumeration.
fcba70d4 492
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493Each variant type selector possess a field name, which is a unique
494identifier within the variant. The identifier is not allowed to use any
495reserved keyword (see Section C.1.2). Replacing reserved keywords with
70375f92 496underscore-prefixed field names is recommended. Fields starting with an
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497underscore should have their leading underscore removed by the CTF trace
498readers.
70375f92 499
4cac83ee 500
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501A named variant declaration followed by its definition within a structure
502declaration:
503
504variant name {
505 field_type sel1;
506 field_type sel2;
507 field_type sel3;
508 ...
509};
510
511struct {
a9b83695 512 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
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513 ...
514 variant name <tag_field> v;
515}
516
517An unnamed variant definition within a structure is expressed by the following
6672e9e1 518TSDL meta-data:
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519
520struct {
a9b83695 521 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
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522 ...
523 variant <tag_field> {
524 field_type sel1;
525 field_type sel2;
526 field_type sel3;
527 ...
528 } v;
529}
530
531Example of a named variant within a sequence that refers to a single tag field:
532
533variant example {
534 uint32_t a;
535 uint64_t b;
536 short c;
537};
538
539struct {
a9b83695 540 enum : uint2_t { a, b, c } choice;
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541 unsigned int seqlen;
542 variant example <choice> v[seqlen];
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543}
544
545Example of an unnamed variant:
546
547struct {
a9b83695 548 enum : uint2_t { a, b, c, d } choice;
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549 /* Unrelated fields can be added between the variant and its tag */
550 int32_t somevalue;
551 variant <choice> {
552 uint32_t a;
553 uint64_t b;
554 short c;
555 struct {
556 unsigned int field1;
557 uint64_t field2;
558 } d;
559 } s;
560}
561
562Example of an unnamed variant within an array:
563
564struct {
a9b83695 565 enum : uint2_t { a, b, c } choice;
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566 variant <choice> {
567 uint32_t a;
568 uint64_t b;
569 short c;
15850440 570 } v[10];
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571}
572
573Example of a variant type definition within a structure, where the defined type
574is then declared within an array of structures. This variant refers to a tag
37ab95c3 575located in an upper static scope. This example clearly shows that a variant
fcba70d4 576type definition referring to the tag "x" uses the closest preceding field from
37ab95c3 577the static scope of the type definition.
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578
579struct {
a9b83695 580 enum : uint2_t { a, b, c, d } x;
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581
582 typedef variant <x> { /*
583 * "x" refers to the preceding "x" enumeration in the
37ab95c3 584 * static scope of the type definition.
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585 */
586 uint32_t a;
587 uint64_t b;
588 short c;
589 } example_variant;
590
591 struct {
a9b83695 592 enum : int { x, y, z } x; /* This enumeration is not used by "v". */
fcba70d4 593 example_variant v; /*
a9b83695 594 * "v" uses the "enum : uint2_t { a, b, c, d }"
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595 * tag.
596 */
597 } a[10];
598}
599
6004.2.3 Arrays
5ba9f198 601
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602Arrays are fixed-length. Their length is declared in the type
603declaration within the meta-data. They contain an array of "inner type"
604elements, which can refer to any type not containing the type of the
605array being declared (no circular dependency). The length is the number
606of elements in an array.
5ba9f198 607
6672e9e1 608TSDL meta-data representation of a named array:
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609
610typedef elem_type name[length];
5ba9f198 611
2152348f 612A nameless array can be declared as a field type within a structure, e.g.:
5ba9f198 613
2152348f 614 uint8_t field_name[10];
80fd2569 615
ec4404a7 616Arrays are always aligned on their element alignment requirement.
5ba9f198 617
fcba70d4 6184.2.4 Sequences
5ba9f198 619
f3afd1c7 620Sequences are dynamically-sized arrays. They refer to a "length"
37ab95c3 621unsigned integer field, which must appear in either the same static scope,
1ab22b2a 622prior to the sequence field (in field declaration order), in an upper
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623static scope, or in an upper dynamic scope (see Section 7.3.2). This
624length field represents the number of elements in the sequence. The
625sequence per se is an array of "inner type" elements.
5ba9f198 626
1ab22b2a 627TSDL meta-data representation for a sequence type definition:
80fd2569 628
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629struct {
630 unsigned int length_field;
631 typedef elem_type typename[length_field];
632 typename seq_field_name;
633}
634
635A sequence can also be declared as a field type, e.g.:
80fd2569 636
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637struct {
638 unsigned int length_field;
639 long seq_field_name[length_field];
640}
80fd2569 641
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642Multiple sequences can refer to the same length field, and these length
643fields can be in a different upper dynamic scope:
644
645e.g., assuming the stream.event.header defines:
646
647stream {
648 ...
649 id = 1;
650 event.header := struct {
651 uint16_t seq_len;
652 };
653};
654
655event {
656 ...
657 stream_id = 1;
658 fields := struct {
659 long seq_a[stream.event.header.seq_len];
660 char seq_b[stream.event.header.seq_len];
661 };
662};
80fd2569 663
1ab22b2a 664The sequence elements follow the "array" specifications.
5ba9f198 665
fcba70d4 6664.2.5 Strings
5ba9f198
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667
668Strings are an array of bytes of variable size and are terminated by a '\0'
6672e9e1
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669"NULL" character. Their encoding is described in the TSDL meta-data. In
670absence of encoding attribute information, the default encoding is
671UTF-8.
5ba9f198 672
6672e9e1 673TSDL meta-data representation of a named string type:
80fd2569 674
359894ac 675typealias string {
5ba9f198 676 encoding = UTF8 OR ASCII;
38b8da21 677} := name;
5ba9f198 678
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679A nameless string type can be declared as a field type:
680
681string field_name; /* Use default UTF8 encoding */
5ba9f198 682
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683Strings are always aligned on byte size.
684
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6855. Event Packet Header
686
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687The event packet header consists of two parts: the "event packet header"
688is the same for all streams of a trace. The second part, the "event
689packet context", is described on a per-stream basis. Both are described
96bf5a3b 690in the TSDL meta-data.
3bf79539 691
6672e9e1 692Event packet header (all fields are optional, specified by TSDL meta-data):
3bf79539 693
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694- Magic number (CTF magic number: 0xC1FC1FC1) specifies that this is a
695 CTF packet. This magic number is optional, but when present, it should
696 come at the very beginning of the packet.
697- Trace UUID, used to ensure the event packet match the meta-data used.
698 (note: we cannot use a meta-data checksum in every cases instead of a
699 UUID because meta-data can be appended to while tracing is active)
700 This field is optional.
701- Stream ID, used as reference to stream description in meta-data.
702 This field is optional if there is only one stream description in the
703 meta-data, but becomes required if there are more than one stream in
704 the TSDL meta-data description.
3bf79539 705
6672e9e1 706Event packet context (all fields are optional, specified by TSDL meta-data):
3bf79539 707
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708- Event packet content size (in bits).
709- Event packet size (in bits, includes padding).
cda89682 710- Event packet content checksum. Checksum excludes the event packet
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711 header.
712- Per-stream event packet sequence count (to deal with UDP packet loss). The
713 number of significant sequence counter bits should also be present, so
b11853af 714 wrap-arounds are dealt with correctly.
6672e9e1 715- Time-stamp at the beginning and time-stamp at the end of the event packet.
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716 Both timestamps are written in the packet header, but sampled respectively
717 while (or before) writing the first event and while (or after) writing the
718 last event in the packet. The inclusive range between these timestamps should
719 include all event timestamps assigned to events contained within the packet.
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720 The timestamp at the beginning of an event packet is guaranteed to be
721 below or equal the timestamp at the end of that event packet.
722 The timestamp at the end of an event packet is guaranteed to be below
723 or equal the timestamps at the end of any following packet within the
724 same stream. See Section 8. Clocks for more detail.
5ba9f198 725- Events discarded count
3bf79539 726 - Snapshot of a per-stream free-running counter, counting the number of
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727 events discarded that were supposed to be written in the stream after
728 the last event in the event packet.
729 * Note: producer-consumer buffer full condition can fill the current
3bf79539 730 event packet with padding so we know exactly where events have been
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731 discarded. However, if the buffer full condition chooses not
732 to fill the current event packet with padding, all we know
733 about the timestamp range in which the events have been
734 discarded is that it is somewhere between the beginning and
735 the end of the packet.
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736- Lossless compression scheme used for the event packet content. Applied
737 directly to raw data. New types of compression can be added in following
738 versions of the format.
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739 0: no compression scheme
740 1: bzip2
741 2: gzip
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742 3: xz
743- Cypher used for the event packet content. Applied after compression.
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744 0: no encryption
745 1: AES
3bf79539 746- Checksum scheme used for the event packet content. Applied after encryption.
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747 0: no checksum
748 1: md5
749 2: sha1
750 3: crc32
751
6672e9e1 7525.1 Event Packet Header Description
3bf79539 753
fc5425db 754The event packet header layout is indicated by the trace packet.header
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755field. Here is a recommended structure type for the packet header with
756the fields typically expected (although these fields are each optional):
fc5425db 757
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758struct event_packet_header {
759 uint32_t magic;
3fde5da1 760 uint8_t uuid[16];
3bf79539 761 uint32_t stream_id;
80fd2569 762};
5ba9f198 763
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764trace {
765 ...
766 packet.header := struct event_packet_header;
767};
768
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769If the magic number is not present, tools such as "file" will have no
770mean to discover the file type.
771
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772If the uuid is not present, no validation that the meta-data actually
773corresponds to the stream is performed.
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774
775If the stream_id packet header field is missing, the trace can only
776contain a single stream. Its "id" field can be left out, and its events
777don't need to declare a "stream_id" field.
778
779
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7805.2 Event Packet Context Description
781
782Event packet context example. These are declared within the stream declaration
6672e9e1 783in the meta-data. All these fields are optional. If the packet size field is
6a7c61df 784missing, the whole stream only contains a single packet. If the content
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785size field is missing, the packet is filled (no padding). The content
786and packet sizes include all headers.
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787
788An example event packet context type:
789
80fd2569 790struct event_packet_context {
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791 uint64_t timestamp_begin;
792 uint64_t timestamp_end;
793 uint32_t checksum;
794 uint32_t stream_packet_count;
795 uint32_t events_discarded;
796 uint32_t cpu_id;
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797 uint64_t/uint32_t/uint16_t content_size;
798 uint64_t/uint32_t/uint16_t packet_size;
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799 uint8_t compression_scheme;
800 uint8_t encryption_scheme;
3b0f8e4d 801 uint8_t checksum_scheme;
3bf79539 802};
5ba9f198 803
fcba70d4 804
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8056. Event Structure
806
807The overall structure of an event is:
808
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8091 - Event Header (as specified by the stream meta-data)
810 2 - Stream Event Context (as specified by the stream meta-data)
811 3 - Event Context (as specified by the event meta-data)
812 4 - Event Payload (as specified by the event meta-data)
5ba9f198 813
fdf2bb05 814This structure defines an implicit dynamic scoping, where variants
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815located in inner structures (those with a higher number in the listing
816above) can refer to the fields of outer structures (with lower number in
6c7226e9 817the listing above). See Section 7.3 TSDL Scopes for more detail.
5ba9f198 818
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819The total length of an event is defined as the difference between the
820end of its Event Payload and the end of the previous event's Event
821Payload. Therefore, it includes the event header alignment padding, and
822all its fields and their respective alignment padding. Events of length
8230 are forbidden.
824
fdf2bb05 8256.1 Event Header
fcba70d4 826
6672e9e1 827Event headers can be described within the meta-data. We hereby propose, as an
fcba70d4
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828example, two types of events headers. Type 1 accommodates streams with less than
82931 event IDs. Type 2 accommodates streams with 31 or more event IDs.
5ba9f198 830
3bf79539
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831One major factor can vary between streams: the number of event IDs assigned to
832a stream. Luckily, this information tends to stay relatively constant (modulo
5ba9f198 833event registration while trace is being recorded), so we can specify different
3bf79539 834representations for streams containing few event IDs and streams containing
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835many event IDs, so we end up representing the event ID and time-stamp as
836densely as possible in each case.
5ba9f198 837
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838The header is extended in the rare occasions where the information cannot be
839represented in the ranges available in the standard event header. They are also
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840used in the rare occasions where the data required for a field could not be
841collected: the flag corresponding to the missing field within the missing_fields
842array is then set to 1.
5ba9f198 843
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844Types uintX_t represent an X-bit unsigned integer, as declared with
845either:
5ba9f198 846
82cbdb16 847 typealias integer { size = X; align = X; signed = false; } := uintX_t;
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848
849 or
850
82cbdb16 851 typealias integer { size = X; align = 1; signed = false; } := uintX_t;
5ba9f198 852
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853For more information about timestamp fields, see Section 8. Clocks.
854
fdf2bb05 8556.1.1 Type 1 - Few event IDs
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856
857 - Aligned on 32-bit (or 8-bit if byte-packed, depending on the architecture
858 preference).
5ba9f198 859 - Native architecture byte ordering.
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860 - For "compact" selection
861 - Fixed size: 32 bits.
862 - For "extended" selection
863 - Size depends on the architecture and variant alignment.
5ba9f198 864
80fd2569 865struct event_header_1 {
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866 /*
867 * id: range: 0 - 30.
868 * id 31 is reserved to indicate an extended header.
869 */
a9b83695 870 enum : uint5_t { compact = 0 ... 30, extended = 31 } id;
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871 variant <id> {
872 struct {
873 uint27_t timestamp;
874 } compact;
875 struct {
876 uint32_t id; /* 32-bit event IDs */
877 uint64_t timestamp; /* 64-bit timestamps */
878 } extended;
879 } v;
cb108fea 880} align(32); /* or align(8) */
5ba9f198 881
5ba9f198 882
fdf2bb05 8836.1.2 Type 2 - Many event IDs
5ba9f198 884
fcba70d4 885 - Aligned on 16-bit (or 8-bit if byte-packed, depending on the architecture
5ba9f198 886 preference).
5ba9f198 887 - Native architecture byte ordering.
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888 - For "compact" selection
889 - Size depends on the architecture and variant alignment.
890 - For "extended" selection
891 - Size depends on the architecture and variant alignment.
5ba9f198 892
80fd2569 893struct event_header_2 {
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894 /*
895 * id: range: 0 - 65534.
896 * id 65535 is reserved to indicate an extended header.
897 */
a9b83695 898 enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;
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899 variant <id> {
900 struct {
901 uint32_t timestamp;
902 } compact;
903 struct {
904 uint32_t id; /* 32-bit event IDs */
905 uint64_t timestamp; /* 64-bit timestamps */
906 } extended;
907 } v;
cb108fea 908} align(16); /* or align(8) */
5ba9f198 909
5ba9f198 910
0b174d87 9116.2 Stream Event Context and Event Context
5ba9f198 912
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913The event context contains information relative to the current event.
914The choice and meaning of this information is specified by the TSDL
915stream and event meta-data descriptions. The stream context is applied
916to all events within the stream. The stream context structure follows
917the event header. The event context is applied to specific events. Its
918structure follows the stream context structure.
5ba9f198 919
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920An example of stream-level event context is to save the event payload size with
921each event, or to save the current PID with each event. These are declared
6672e9e1 922within the stream declaration within the meta-data:
5ba9f198 923
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924 stream {
925 ...
6672e9e1 926 event.context := struct {
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MD
927 uint pid;
928 uint16_t payload_size;
6672e9e1 929 };
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MD
930 };
931
932An example of event-specific event context is to declare a bitmap of missing
933fields, only appended after the stream event context if the extended event
934header is selected. NR_FIELDS is the number of fields within the event (a
935numeric value).
5ba9f198 936
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937 event {
938 context = struct {
939 variant <id> {
940 struct { } compact;
941 struct {
942 uint1_t missing_fields[NR_FIELDS]; /* missing event fields bitmap */
943 } extended;
944 } v;
945 };
946 ...
947 }
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948
9496.3 Event Payload
950
951An event payload contains fields specific to a given event type. The fields
6672e9e1 952belonging to an event type are described in the event-specific meta-data
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MD
953within a structure type.
954
9556.3.1 Padding
956
957No padding at the end of the event payload. This differs from the ISO/C standard
958for structures, but follows the CTF standard for structures. In a trace, even
959though it makes sense to align the beginning of a structure, it really makes no
960sense to add padding at the end of the structure, because structures are usually
961not followed by a structure of the same type.
962
963This trick can be done by adding a zero-length "end" field at the end of the C
964structures, and by using the offset of this field rather than using sizeof()
3bf79539 965when calculating the size of a structure (see Appendix "A. Helper macros").
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MD
966
9676.3.2 Alignment
968
969The event payload is aligned on the largest alignment required by types
970contained within the payload. (This follows the ISO/C standard for structures)
971
972
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MD
9737. Trace Stream Description Language (TSDL)
974
975The Trace Stream Description Language (TSDL) allows expression of the
976binary trace streams layout in a C99-like Domain Specific Language
977(DSL).
978
979
6672e9e1 9807.1 Meta-data
6c7226e9
MD
981
982The trace stream layout description is located in the trace meta-data.
983The meta-data is itself located in a stream identified by its name:
984"metadata".
5ba9f198 985
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MD
986The meta-data description can be expressed in two different formats:
987text-only and packet-based. The text-only description facilitates
988generation of meta-data and provides a convenient way to enter the
989meta-data information by hand. The packet-based meta-data provides the
990CTF stream packet facilities (checksumming, compression, encryption,
991network-readiness) for meta-data stream generated and transported by a
992tracer.
993
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994The text-only meta-data file is a plain-text TSDL description. This file
995must begin with the following characters to identify the file as a CTF
9486a18c 996TSDL text-based metadata file (without the double-quotes) :
1b4d35eb 997
ec2b4db8 998"/* CTF"
1b4d35eb 999
ec2b4db8
MD
1000It must be followed by a space, and the version of the specification
1001followed by the CTF trace, e.g.:
1002
1003" 1.8"
1004
1005These characters allow automated discovery of file type and CTF
1006specification version. They are interpreted as a the beginning of a
1007comment by the TSDL metadata parser. The comment can be continued to
1008contain extra commented characters before it is closed.
6672e9e1
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1009
1010The packet-based meta-data is made of "meta-data packets", which each
1011start with a meta-data packet header. The packet-based meta-data
1012description is detected by reading the magic number "0x75D11D57" at the
1013beginning of the file. This magic number is also used to detect the
1014endianness of the architecture by trying to read the CTF magic number
1015and its counterpart in reversed endianness. The events within the
1016meta-data stream have no event header nor event context. Each event only
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MD
1017contains a special "sequence" payload, which is a sequence of bits which
1018length is implicitly calculated by using the
1019"trace.packet.header.content_size" field, minus the packet header size.
1020The formatting of this sequence of bits is a plain-text representation
1021of the TSDL description. Each meta-data packet start with a special
1022packet header, specific to the meta-data stream, which contains,
1023exactly:
6672e9e1
MD
1024
1025struct metadata_packet_header {
2daeaa3a 1026 uint32_t magic; /* 0x75D11D57 */
3fde5da1 1027 uint8_t uuid[16]; /* Unique Universal Identifier */
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1028 uint32_t checksum; /* 0 if unused */
1029 uint32_t content_size; /* in bits */
1030 uint32_t packet_size; /* in bits */
1031 uint8_t compression_scheme; /* 0 if unused */
1032 uint8_t encryption_scheme; /* 0 if unused */
1033 uint8_t checksum_scheme; /* 0 if unused */
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1034 uint8_t major; /* CTF spec version major number */
1035 uint8_t minor; /* CTF spec version minor number */
6672e9e1
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1036};
1037
1038The packet-based meta-data can be converted to a text-only meta-data by
3568031f 1039concatenating all the strings it contains.
4fafe1ad 1040
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1041In the textual representation of the meta-data, the text contained
1042within "/*" and "*/", as well as within "//" and end of line, are
1043treated as comments. Boolean values can be represented as true, TRUE,
1044or 1 for true, and false, FALSE, or 0 for false. Within the string-based
1045meta-data description, the trace UUID is represented as a string of
1046hexadecimal digits and dashes "-". In the event packet header, the trace
1047UUID is represented as an array of bytes.
fcba70d4 1048
fdf2bb05 1049
6c7226e9 10507.2 Declaration vs Definition
fdf2bb05
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1051
1052A declaration associates a layout to a type, without specifying where
1053this type is located in the event structure hierarchy (see Section 6).
1054This therefore includes typedef, typealias, as well as all type
1055specifiers. In certain circumstances (typedef, structure field and
1056variant field), a declaration is followed by a declarator, which specify
1057the newly defined type name (for typedef), or the field name (for
1058declarations located within structure and variants). Array and sequence,
1059declared with square brackets ("[" "]"), are part of the declarator,
a9b83695 1060similarly to C99. The enumeration base type is specified by
6c7226e9 1061": enum_base", which is part of the type specifier. The variant tag
a9b83695 1062name, specified between "<" ">", is also part of the type specifier.
fdf2bb05
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1063
1064A definition associates a type to a location in the event structure
b9606a77
MD
1065hierarchy (see Section 6). This association is denoted by ":=", as shown
1066in Section 7.3.
fdf2bb05
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1067
1068
6c7226e9 10697.3 TSDL Scopes
fdf2bb05 1070
37ab95c3
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1071TSDL uses three different types of scoping: a lexical scope is used for
1072declarations and type definitions, and static and dynamic scopes are
1073used for variants references to tag fields (with relative and absolute
1074path lookups) and for sequence references to length fields.
fdf2bb05 1075
6c7226e9 10767.3.1 Lexical Scope
fdf2bb05 1077
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1078Each of "trace", "env", "stream", "event", "struct" and "variant" have
1079their own nestable declaration scope, within which types can be declared
1080using "typedef" and "typealias". A root declaration scope also contains
1081all declarations located outside of any of the aforementioned
1082declarations. An inner declaration scope can refer to type declared
1083within its container lexical scope prior to the inner declaration scope.
1084Redefinition of a typedef or typealias is not valid, although hiding an
1085upper scope typedef or typealias is allowed within a sub-scope.
fdf2bb05 1086
37ab95c3 10877.3.2 Static and Dynamic Scopes
fdf2bb05 1088
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MD
1089A local static scope consists in the scope generated by the declaration
1090of fields within a compound type. A static scope is a local static scope
1091augmented with the nested sub-static-scopes it contains.
1092
1093A dynamic scope consists in the static scope augmented with the
7d9d7e92 1094implicit event structure definition hierarchy presented at Section 6.
fdf2bb05 1095
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1096Multiple declarations of the same field name within a local static scope
1097is not valid. It is however valid to re-use the same field name in
1098different local scopes.
1099
1100Nested static and dynamic scopes form lookup paths. These are used for
1101variant tag and sequence length references. They are used at the variant
1102and sequence definition site to look up the location of the tag field
1103associated with a variant, and to lookup up the location of the length
1104field associated with a sequence.
1105
1106Variants and sequences can refer to a tag field either using a relative
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1107path or an absolute path. The relative path is relative to the scope in
1108which the variant or sequence performing the lookup is located.
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1109Relative paths are only allowed to lookup within the same static scope,
1110which includes its nested static scopes. Lookups targeting parent static
1111scopes need to be performed with an absolute path.
1112
1113Absolute path lookups use the full path including the dynamic scope
1114followed by a "." and then the static scope. Therefore, variants (or
1115sequences) in lower levels in the dynamic scope (e.g. event context) can
1116refer to a tag (or length) field located in upper levels (e.g. in the
1117event header) by specifying, in this case, the associated tag with
1118<stream.event.header.field_name>. This allows, for instance, the event
1119context to define a variant referring to the "id" field of the event
1120header as selector.
1121
284724ae 1122The dynamic scope prefixes are thus:
fdf2bb05 1123
570ecabe 1124 - Trace Environment: <env. >,
e0d9e2c7 1125 - Trace Packet Header: <trace.packet.header. >,
7d9d7e92
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1126 - Stream Packet Context: <stream.packet.context. >,
1127 - Event Header: <stream.event.header. >,
1128 - Stream Event Context: <stream.event.context. >,
1129 - Event Context: <event.context. >,
1130 - Event Payload: <event.fields. >.
fdf2bb05 1131
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1132
1133The target dynamic scope must be specified explicitly when referring to
4cac83ee
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1134a field outside of the static scope (absolute scope reference). No
1135conflict can occur between relative and dynamic paths, because the
1136keywords "trace", "stream", and "event" are reserved, and thus
1137not permitted as field names. It is recommended that field names
1138clashing with CTF and C99 reserved keywords use an underscore prefix to
1139eliminate the risk of generating a description containing an invalid
70375f92 1140field name. Consequently, fields starting with an underscore should have
92250c71 1141their leading underscore removed by the CTF trace readers.
70375f92 1142
fdf2bb05 1143
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1144The information available in the dynamic scopes can be thought of as the
1145current tracing context. At trace production, information about the
1146current context is saved into the specified scope field levels. At trace
1147consumption, for each event, the current trace context is therefore
1148readable by accessing the upper dynamic scopes.
1149
fdf2bb05 1150
6c7226e9 11517.4 TSDL Examples
d285084f 1152
6672e9e1 1153The grammar representing the TSDL meta-data is presented in Appendix C.
7df6b93a 1154TSDL Grammar. This section presents a rather lighter reading that
6672e9e1 1155consists in examples of TSDL meta-data, with template values.
969f30c0 1156
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MD
1157The stream "id" can be left out if there is only one stream in the
1158trace. The event "id" field can be left out if there is only one event
1159in a stream.
1160
5ba9f198 1161trace {
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MD
1162 major = value; /* CTF spec version major number */
1163 minor = value; /* CTF spec version minor number */
fdf2bb05 1164 uuid = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"; /* Trace UUID */
58997e9e 1165 byte_order = be OR le; /* Endianness (required) */
fc5425db
MD
1166 packet.header := struct {
1167 uint32_t magic;
3fde5da1 1168 uint8_t uuid[16];
fc5425db
MD
1169 uint32_t stream_id;
1170 };
3bf79539 1171};
5ba9f198 1172
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MD
1173/*
1174 * The "env" (environment) scope contains assignment expressions. The
1175 * field names and content are implementation-defined.
1176 */
1177env {
1178 pid = value; /* example */
1179 proc_name = "name"; /* example */
1180 ...
1181};
1182
3bf79539
MD
1183stream {
1184 id = stream_id;
fdf2bb05 1185 /* Type 1 - Few event IDs; Type 2 - Many event IDs. See section 6.1. */
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MD
1186 event.header := event_header_1 OR event_header_2;
1187 event.context := struct {
77a98c82 1188 ...
3bf79539 1189 };
4fa992a5 1190 packet.context := struct {
77a98c82 1191 ...
3bf79539
MD
1192 };
1193};
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MD
1194
1195event {
980015f9 1196 name = "event_name";
3bf79539 1197 id = value; /* Numeric identifier within the stream */
67f02e24 1198 stream_id = stream_id;
dc56f167 1199 loglevel = value;
8e9060f2 1200 model.emf.uri = "string";
4fa992a5 1201 context := struct {
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MD
1202 ...
1203 };
4fa992a5 1204 fields := struct {
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MD
1205 ...
1206 };
3bf79539 1207};
5ba9f198 1208
555f54e6
MD
1209callsite {
1210 name = "event_name";
1211 func = "func_name";
1212 file = "myfile.c";
1213 line = 39;
5a6b4ee1 1214 ip = 0x40096c;
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MD
1215};
1216
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MD
1217/* More detail on types in section 4. Types */
1218
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MD
1219/*
1220 * Named types:
1221 *
4fa992a5 1222 * Type declarations behave similarly to the C standard.
3d13ef1a
MD
1223 */
1224
80af8ac6 1225typedef aliased_type_specifiers new_type_declarators;
2152348f 1226
3d13ef1a 1227/* e.g.: typedef struct example new_type_name[10]; */
80fd2569 1228
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MD
1229/*
1230 * typealias
1231 *
1232 * The "typealias" declaration can be used to give a name (including
80af8ac6
MD
1233 * pointer declarator specifier) to a type. It should also be used to
1234 * map basic C types (float, int, unsigned long, ...) to a CTF type.
1235 * Typealias is a superset of "typedef": it also allows assignment of a
38b8da21 1236 * simple variable identifier to a type.
4fa992a5
MD
1237 */
1238
1239typealias type_class {
80fd2569 1240 ...
38b8da21 1241} := type_specifiers type_declarator;
2152348f 1242
3d13ef1a
MD
1243/*
1244 * e.g.:
4fa992a5 1245 * typealias integer {
3d13ef1a
MD
1246 * size = 32;
1247 * align = 32;
1248 * signed = false;
38b8da21 1249 * } := struct page *;
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MD
1250 *
1251 * typealias integer {
1252 * size = 32;
1253 * align = 32;
1254 * signed = true;
38b8da21 1255 * } := int;
3d13ef1a 1256 */
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MD
1257
1258struct name {
3bf79539
MD
1259 ...
1260};
5ba9f198 1261
fcba70d4
MD
1262variant name {
1263 ...
1264};
1265
a9b83695 1266enum name : integer_type {
3bf79539
MD
1267 ...
1268};
1269
2152348f 1270
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MD
1271/*
1272 * Unnamed types, contained within compound type fields, typedef or typealias.
1273 */
2152348f 1274
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MD
1275struct {
1276 ...
2152348f 1277}
5ba9f198 1278
ec4404a7
MD
1279struct {
1280 ...
1281} align(value)
1282
fcba70d4
MD
1283variant {
1284 ...
1285}
1286
a9b83695 1287enum : integer_type {
80fd2569 1288 ...
2152348f
MD
1289}
1290
1291typedef type new_type[length];
3bf79539 1292
2152348f
MD
1293struct {
1294 type field_name[length];
1295}
1296
1297typedef type new_type[length_type];
1298
1299struct {
1300 type field_name[length_type];
1301}
1302
1303integer {
80fd2569 1304 ...
2152348f 1305}
3bf79539 1306
2152348f 1307floating_point {
80fd2569 1308 ...
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MD
1309}
1310
1311struct {
1312 integer_type field_name:size; /* GNU/C bitfield */
1313}
1314
1315struct {
1316 string field_name;
1317}
3bf79539 1318
fcba70d4 1319
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MD
13208. Clocks
1321
1322Clock metadata allows to describe the clock topology of the system, as
1323well as to detail each clock parameter. In absence of clock description,
1324it is assumed that all fields named "timestamp" use the same clock
aed18b5e 1325source, which increments once per nanosecond.
2fa70eba
MD
1326
1327Describing a clock and how it is used by streams is threefold: first,
1328the clock and clock topology should be described in a "clock"
1329description block, e.g.:
1330
d803bfcb 1331clock {
58262d97 1332 name = cycle_counter_sync;
2fa70eba 1333 uuid = "62189bee-96dc-11e0-91a8-cfa3d89f3923";
58262d97 1334 description = "Cycle counter synchronized across CPUs";
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MD
1335 freq = 1000000000; /* frequency, in Hz */
1336 /* precision in seconds is: 1000 * (1/freq) */
1337 precision = 1000;
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MD
1338 /*
1339 * clock value offset from Epoch is:
1340 * offset_s + (offset * (1/freq))
1341 */
1342 offset_s = 1326476837;
1343 offset = 897235420;
ce0fadbd 1344 absolute = FALSE;
2fa70eba
MD
1345};
1346
d803bfcb
MD
1347The mandatory "name" field specifies the name of the clock identifier,
1348which can later be used as a reference. The optional field "uuid" is the
1349unique identifier of the clock. It can be used to correlate different
1350traces that use the same clock. An optional textual description string
1351can be added with the "description" field. The "freq" field is the
1352initial frequency of the clock, in Hz. If the "freq" field is not
1353present, the frequency is assumed to be 1000000000 (providing clock
1354increment of 1 ns). The optional "precision" field details the
a40cccda
MD
1355uncertainty on the clock measurements, in (1/freq) units. The "offset_s"
1356and "offset" fields indicate the offset from POSIX.1 Epoch, 1970-01-01
135700:00:00 +0000 (UTC), to the zero of value of the clock. The "offset_s"
1358field is in seconds. The "offset" field is in (1/freq) units. If any of
1359the "offset_s" or "offset" field is not present, it is assigned the 0
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MD
1360value. The field "absolute" is TRUE if the clock is a global reference
1361across different clock uuid (e.g. NTP time). Otherwise, "absolute" is
1362FALSE, and the clock can be considered as synchronized only with other
1363clocks that have the same uuid.
1364
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MD
1365
1366Secondly, a reference to this clock should be added within an integer
1367type:
1368
1369typealias integer {
1370 size = 64; align = 1; signed = false;
58262d97 1371 map = clock.cycle_counter_sync.value;
2fa70eba
MD
1372} := uint64_ccnt_t;
1373
1374Thirdly, stream declarations can reference the clock they use as a
1375time-stamp source:
1376
1377struct packet_context {
1378 uint64_ccnt_t ccnt_begin;
1379 uint64_ccnt_t ccnt_end;
1380 /* ... */
1381};
1382
1383stream {
1384 /* ... */
1385 event.header := struct {
1386 uint64_ccnt_t timestamp;
1387 /* ... */
1388 }
1389 packet.context := struct packet_context;
1390};
1391
1392For a N-bit integer type referring to a clock, if the integer overflows
2a0bae9e
MD
1393compared to the N low order bits of the clock prior value found in the
1394same stream, then it is assumed that one, and only one, overflow
1395occurred. It is therefore important that events encoding time on a small
1396number of bits happen frequently enough to detect when more than one
1397N-bit overflow occurs.
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MD
1398
1399In a packet context, clock field names ending with "_begin" and "_end"
1400have a special meaning: this refers to the time-stamps at, respectively,
1401the beginning and the end of each packet.
1402
1403
3bf79539 1404A. Helper macros
5ba9f198
MD
1405
1406The two following macros keep track of the size of a GNU/C structure without
1407padding at the end by placing HEADER_END as the last field. A one byte end field
1408is used for C90 compatibility (C99 flexible arrays could be used here). Note
1409that this does not affect the effective structure size, which should always be
1410calculated with the header_sizeof() helper.
1411
1412#define HEADER_END char end_field
1413#define header_sizeof(type) offsetof(typeof(type), end_field)
3bf79539
MD
1414
1415
1416B. Stream Header Rationale
1417
1418An event stream is divided in contiguous event packets of variable size. These
1419subdivisions allow the trace analyzer to perform a fast binary search by time
1420within the stream (typically requiring to index only the event packet headers)
1421without reading the whole stream. These subdivisions have a variable size to
1422eliminate the need to transfer the event packet padding when partially filled
1423event packets must be sent when streaming a trace for live viewing/analysis.
1424An event packet can contain a certain amount of padding at the end. Dividing
1425streams into event packets is also useful for network streaming over UDP and
1426flight recorder mode tracing (a whole event packet can be swapped out of the
1427buffer atomically for reading).
1428
1429The stream header is repeated at the beginning of each event packet to allow
1430flexibility in terms of:
1431
1432 - streaming support,
1433 - allowing arbitrary buffers to be discarded without making the trace
1434 unreadable,
1435 - allow UDP packet loss handling by either dealing with missing event packet
1436 or asking for re-transmission.
1437 - transparently support flight recorder mode,
1438 - transparently support crash dump.
1439
6c7226e9
MD
1440
1441C. TSDL Grammar
fcba70d4 1442
4fa992a5 1443/*
6c7226e9 1444 * Common Trace Format (CTF) Trace Stream Description Language (TSDL) Grammar.
4fa992a5
MD
1445 *
1446 * Inspired from the C99 grammar:
1447 * http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf (Annex A)
6c7226e9
MD
1448 * and c++1x grammar (draft)
1449 * http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3291.pdf (Annex A)
4fa992a5
MD
1450 *
1451 * Specialized for CTF needs by including only constant and declarations from
1452 * C99 (excluding function declarations), and by adding support for variants,
6c7226e9
MD
1453 * sequences and CTF-specific specifiers. Enumeration container types
1454 * semantic is inspired from c++1x enum-base.
4fa992a5
MD
1455 */
1456
14571) Lexical grammar
1458
14591.1) Lexical elements
1460
1461token:
1462 keyword
1463 identifier
1464 constant
1465 string-literal
1466 punctuator
1467
14681.2) Keywords
1469
1470keyword: is one of
1471
ec4404a7 1472align
dbb8b280 1473callsite
4fa992a5
MD
1474const
1475char
2fa70eba 1476clock
4fa992a5
MD
1477double
1478enum
570ecabe 1479env
4fa992a5
MD
1480event
1481floating_point
1482float
1483integer
1484int
1485long
1486short
1487signed
1488stream
1489string
1490struct
1491trace
3e1e1a78 1492typealias
4fa992a5
MD
1493typedef
1494unsigned
1495variant
1496void
1497_Bool
1498_Complex
1499_Imaginary
1500
1501
15021.3) Identifiers
1503
1504identifier:
1505 identifier-nondigit
1506 identifier identifier-nondigit
1507 identifier digit
1508
1509identifier-nondigit:
1510 nondigit
1511 universal-character-name
1512 any other implementation-defined characters
1513
1514nondigit:
1515 _
1516 [a-zA-Z] /* regular expression */
1517
1518digit:
1519 [0-9] /* regular expression */
1520
15211.4) Universal character names
1522
1523universal-character-name:
1524 \u hex-quad
1525 \U hex-quad hex-quad
1526
1527hex-quad:
1528 hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
1529
15301.5) Constants
1531
1532constant:
1533 integer-constant
1534 enumeration-constant
1535 character-constant
1536
1537integer-constant:
1538 decimal-constant integer-suffix-opt
1539 octal-constant integer-suffix-opt
1540 hexadecimal-constant integer-suffix-opt
1541
1542decimal-constant:
1543 nonzero-digit
1544 decimal-constant digit
1545
1546octal-constant:
1547 0
1548 octal-constant octal-digit
1549
1550hexadecimal-constant:
1551 hexadecimal-prefix hexadecimal-digit
1552 hexadecimal-constant hexadecimal-digit
1553
1554hexadecimal-prefix:
1555 0x
1556 0X
1557
1558nonzero-digit:
1559 [1-9]
1560
1561integer-suffix:
1562 unsigned-suffix long-suffix-opt
1563 unsigned-suffix long-long-suffix
1564 long-suffix unsigned-suffix-opt
1565 long-long-suffix unsigned-suffix-opt
1566
1567unsigned-suffix:
1568 u
1569 U
1570
1571long-suffix:
1572 l
1573 L
1574
1575long-long-suffix:
1576 ll
1577 LL
1578
4fa992a5
MD
1579enumeration-constant:
1580 identifier
1581 string-literal
1582
1583character-constant:
1584 ' c-char-sequence '
1585 L' c-char-sequence '
1586
1587c-char-sequence:
1588 c-char
1589 c-char-sequence c-char
1590
1591c-char:
1592 any member of source charset except single-quote ('), backslash
1593 (\), or new-line character.
1594 escape-sequence
1595
1596escape-sequence:
1597 simple-escape-sequence
1598 octal-escape-sequence
1599 hexadecimal-escape-sequence
1600 universal-character-name
1601
1602simple-escape-sequence: one of
1603 \' \" \? \\ \a \b \f \n \r \t \v
1604
1605octal-escape-sequence:
1606 \ octal-digit
1607 \ octal-digit octal-digit
1608 \ octal-digit octal-digit octal-digit
1609
1610hexadecimal-escape-sequence:
1611 \x hexadecimal-digit
1612 hexadecimal-escape-sequence hexadecimal-digit
1613
16141.6) String literals
1615
1616string-literal:
1617 " s-char-sequence-opt "
1618 L" s-char-sequence-opt "
1619
1620s-char-sequence:
1621 s-char
1622 s-char-sequence s-char
1623
1624s-char:
1625 any member of source charset except double-quote ("), backslash
1626 (\), or new-line character.
1627 escape-sequence
1628
16291.7) Punctuators
1630
1631punctuator: one of
1632 [ ] ( ) { } . -> * + - < > : ; ... = ,
1633
1634
16352) Phrase structure grammar
1636
1637primary-expression:
1638 identifier
1639 constant
1640 string-literal
1641 ( unary-expression )
1642
1643postfix-expression:
1644 primary-expression
1645 postfix-expression [ unary-expression ]
1646 postfix-expression . identifier
1647 postfix-expressoin -> identifier
1648
1649unary-expression:
1650 postfix-expression
1651 unary-operator postfix-expression
1652
1653unary-operator: one of
1654 + -
1655
4fa992a5
MD
1656assignment-operator:
1657 =
1658
b9606a77
MD
1659type-assignment-operator:
1660 :=
1661
4fa992a5 1662constant-expression-range:
73d61ac3 1663 unary-expression ... unary-expression
4fa992a5
MD
1664
16652.2) Declarations:
1666
1667declaration:
689e04b4 1668 declaration-specifiers declarator-list-opt ;
4fa992a5
MD
1669 ctf-specifier ;
1670
1671declaration-specifiers:
689e04b4 1672 storage-class-specifier declaration-specifiers-opt
4fa992a5
MD
1673 type-specifier declaration-specifiers-opt
1674 type-qualifier declaration-specifiers-opt
1675
1676declarator-list:
1677 declarator
1678 declarator-list , declarator
1679
d285084f
MD
1680abstract-declarator-list:
1681 abstract-declarator
1682 abstract-declarator-list , abstract-declarator
1683
4fa992a5
MD
1684storage-class-specifier:
1685 typedef
1686
1687type-specifier:
1688 void
1689 char
1690 short
1691 int
1692 long
1693 float
1694 double
1695 signed
1696 unsigned
1697 _Bool
1698 _Complex
cfdd51ec 1699 _Imaginary
9dfcfc0f
MD
1700 struct-specifier
1701 variant-specifier
4fa992a5
MD
1702 enum-specifier
1703 typedef-name
1704 ctf-type-specifier
1705
ec4404a7 1706align-attribute:
73d61ac3 1707 align ( unary-expression )
ec4404a7 1708
4fa992a5 1709struct-specifier:
ec4404a7
MD
1710 struct identifier-opt { struct-or-variant-declaration-list-opt } align-attribute-opt
1711 struct identifier align-attribute-opt
4fa992a5
MD
1712
1713struct-or-variant-declaration-list:
1714 struct-or-variant-declaration
1715 struct-or-variant-declaration-list struct-or-variant-declaration
1716
1717struct-or-variant-declaration:
1718 specifier-qualifier-list struct-or-variant-declarator-list ;
eacb16d1 1719 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list ;
6143bab7
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1720 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list ;
1721 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list ;
4fa992a5
MD
1722
1723specifier-qualifier-list:
1724 type-specifier specifier-qualifier-list-opt
1725 type-qualifier specifier-qualifier-list-opt
1726
1727struct-or-variant-declarator-list:
1728 struct-or-variant-declarator
1729 struct-or-variant-declarator-list , struct-or-variant-declarator
1730
1731struct-or-variant-declarator:
1732 declarator
73d61ac3 1733 declarator-opt : unary-expression
4fa992a5
MD
1734
1735variant-specifier:
1736 variant identifier-opt variant-tag-opt { struct-or-variant-declaration-list }
1737 variant identifier variant-tag
1738
1739variant-tag:
37ab95c3 1740 < unary-expression >
4fa992a5
MD
1741
1742enum-specifier:
1743 enum identifier-opt { enumerator-list }
1744 enum identifier-opt { enumerator-list , }
1745 enum identifier
a9b83695
MD
1746 enum identifier-opt : declaration-specifiers { enumerator-list }
1747 enum identifier-opt : declaration-specifiers { enumerator-list , }
4fa992a5
MD
1748
1749enumerator-list:
1750 enumerator
1751 enumerator-list , enumerator
1752
1753enumerator:
1754 enumeration-constant
8d2d41f7
MD
1755 enumeration-constant assignment-operator unary-expression
1756 enumeration-constant assignment-operator constant-expression-range
4fa992a5
MD
1757
1758type-qualifier:
1759 const
1760
1761declarator:
1762 pointer-opt direct-declarator
1763
1764direct-declarator:
1765 identifier
1766 ( declarator )
1ab22b2a 1767 direct-declarator [ unary-expression ]
4fa992a5 1768
d285084f
MD
1769abstract-declarator:
1770 pointer-opt direct-abstract-declarator
1771
1772direct-abstract-declarator:
1773 identifier-opt
1774 ( abstract-declarator )
1ab22b2a 1775 direct-abstract-declarator [ unary-expression ]
d285084f
MD
1776 direct-abstract-declarator [ ]
1777
4fa992a5 1778pointer:
3b0f8e4d
MD
1779 * type-qualifier-list-opt
1780 * type-qualifier-list-opt pointer
4fa992a5
MD
1781
1782type-qualifier-list:
1783 type-qualifier
1784 type-qualifier-list type-qualifier
1785
4fa992a5
MD
1786typedef-name:
1787 identifier
1788
17892.3) CTF-specific declarations
1790
1791ctf-specifier:
662baf84 1792 clock { ctf-assignment-expression-list-opt }
4fa992a5
MD
1793 event { ctf-assignment-expression-list-opt }
1794 stream { ctf-assignment-expression-list-opt }
570ecabe 1795 env { ctf-assignment-expression-list-opt }
4fa992a5 1796 trace { ctf-assignment-expression-list-opt }
555f54e6 1797 callsite { ctf-assignment-expression-list-opt }
b12919a5
MD
1798 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1799 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
4fa992a5
MD
1800
1801ctf-type-specifier:
1802 floating_point { ctf-assignment-expression-list-opt }
1803 integer { ctf-assignment-expression-list-opt }
1804 string { ctf-assignment-expression-list-opt }
7609d3c7 1805 string
4fa992a5
MD
1806
1807ctf-assignment-expression-list:
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MD
1808 ctf-assignment-expression ;
1809 ctf-assignment-expression-list ctf-assignment-expression ;
4fa992a5
MD
1810
1811ctf-assignment-expression:
1812 unary-expression assignment-operator unary-expression
1813 unary-expression type-assignment-operator type-specifier
eacb16d1 1814 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list
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1815 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1816 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
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