trace_uuid -> uuid
[ctf.git] / common-trace-format-proposal.txt
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5ba9f198 1
4767a9e7 2RFC: Common Trace Format (CTF) Proposal (pre-v1.7)
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3
4Mathieu Desnoyers, EfficiOS Inc.
5
6The goal of the present document is to propose a trace format that suits the
cc089c3a 7needs of the embedded, telecom, high-performance and kernel communities. It is
5ba9f198 8based on the Common Trace Format Requirements (v1.4) document. It is designed to
cc089c3a 9allow traces to be natively generated by the Linux kernel, Linux user-space
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10applications written in C/C++, and hardware components. One major element of
11CTF is the Trace Stream Description Language (TSDL) which flexibility
12enables description of various binary trace stream layouts.
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13
14The latest version of this document can be found at:
15
16 git tree: git://git.efficios.com/ctf.git
17 gitweb: http://git.efficios.com/?p=ctf.git
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18
19A reference implementation of a library to read and write this trace format is
20being implemented within the BabelTrace project, a converter between trace
21formats. The development tree is available at:
22
23 git tree: git://git.efficios.com/babeltrace.git
24 gitweb: http://git.efficios.com/?p=babeltrace.git
25
26
271. Preliminary definitions
28
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29 - Event Trace: An ordered sequence of events.
30 - Event Stream: An ordered sequence of events, containing a subset of the
31 trace event types.
32 - Event Packet: A sequence of physically contiguous events within an event
33 stream.
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34 - Event: This is the basic entry in a trace. (aka: a trace record).
35 - An event identifier (ID) relates to the class (a type) of event within
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36 an event stream.
37 e.g. event: irq_entry.
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38 - An event (or event record) relates to a specific instance of an event
39 class.
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40 e.g. event: irq_entry, at time X, on CPU Y
41 - Source Architecture: Architecture writing the trace.
42 - Reader Architecture: Architecture reading the trace.
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43
44
452. High-level representation of a trace
46
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47A trace is divided into multiple event streams. Each event stream contains a
48subset of the trace event types.
5ba9f198 49
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50The final output of the trace, after its generation and optional transport over
51the network, is expected to be either on permanent or temporary storage in a
52virtual file system. Because each event stream is appended to while a trace is
53being recorded, each is associated with a separate file for output. Therefore,
54a stored trace can be represented as a directory containing one file per stream.
5ba9f198 55
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56Meta-data description associated with the trace contains information on
57trace event types expressed in the Trace Stream Description Language
58(TSDL). This language describes:
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59
60- Trace version.
61- Types available.
6672e9e1 62- Per-trace event header description.
3bf79539 63- Per-stream event header description.
6672e9e1 64- Per-stream event context description.
5ba9f198 65- Per-event
3bf79539 66 - Event type to stream mapping.
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67 - Event type to name mapping.
68 - Event type to ID mapping.
6672e9e1 69 - Event context description.
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70 - Event fields description.
71
72
3bf79539 733. Event stream
5ba9f198 74
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75An event stream can be divided into contiguous event packets of variable
76size. These subdivisions have a variable size. An event packet can
77contain a certain amount of padding at the end. The stream header is
78repeated at the beginning of each event packet. The rationale for the
79event stream design choices is explained in Appendix B. Stream Header
80Rationale.
5ba9f198 81
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82The event stream header will therefore be referred to as the "event packet
83header" throughout the rest of this document.
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84
85
864. Types
87
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88Types are organized as type classes. Each type class belong to either of two
89kind of types: basic types or compound types.
90
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914.1 Basic types
92
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93A basic type is a scalar type, as described in this section. It includes
94integers, GNU/C bitfields, enumerations, and floating point values.
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95
964.1.1 Type inheritance
97
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98Type specifications can be inherited to allow deriving types from a
99type class. For example, see the uint32_t named type derived from the "integer"
100type class below ("Integers" section). Types have a precise binary
101representation in the trace. A type class has methods to read and write these
102types, but must be derived into a type to be usable in an event field.
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103
1044.1.2 Alignment
105
106We define "byte-packed" types as aligned on the byte size, namely 8-bit.
107We define "bit-packed" types as following on the next bit, as defined by the
370eae99 108"Integers" section.
5ba9f198 109
6672e9e1 110Each basic type must specify its alignment, in bits. Examples of
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111possible alignments are: bit-packed (align = 1), byte-packed (align =
1128), or word-aligned (e.g. align = 32 or align = 64). The choice depends
113on the architecture preference and compactness vs performance trade-offs
114of the implementation. Architectures providing fast unaligned write
115byte-packed basic types to save space, aligning each type on byte
116boundaries (8-bit). Architectures with slow unaligned writes align types
117on specific alignment values. If no specific alignment is declared for a
118type, it is assumed to be bit-packed for integers with size not multiple
119of 8 bits and for gcc bitfields. All other basic types are byte-packed
120by default. It is however recommended to always specify the alignment
121explicitly. Alignment values must be power of two. Compound types are
122aligned as specified in their individual specification.
5ba9f198 123
6672e9e1 124TSDL meta-data attribute representation of a specific alignment:
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125
126 align = value; /* value in bits */
127
1284.1.3 Byte order
129
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130By default, the native endianness of the source architecture the trace is used.
131Byte order can be overridden for a basic type by specifying a "byte_order"
132attribute. Typical use-case is to specify the network byte order (big endian:
133"be") to save data captured from the network into the trace without conversion.
134If not specified, the byte order is native.
5ba9f198 135
6672e9e1 136TSDL meta-data representation:
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137
138 byte_order = native OR network OR be OR le; /* network and be are aliases */
139
1404.1.4 Size
141
142Type size, in bits, for integers and floats is that returned by "sizeof()" in C
143multiplied by CHAR_BIT.
144We require the size of "char" and "unsigned char" types (CHAR_BIT) to be fixed
145to 8 bits for cross-endianness compatibility.
146
6672e9e1 147TSDL meta-data representation:
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148
149 size = value; (value is in bits)
150
1514.1.5 Integers
152
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153Signed integers are represented in two-complement. Integer alignment,
154size, signedness and byte ordering are defined in the TSDL meta-data.
155Integers aligned on byte size (8-bit) and with length multiple of byte
156size (8-bit) correspond to the C99 standard integers. In addition,
157integers with alignment and/or size that are _not_ a multiple of the
158byte size are permitted; these correspond to the C99 standard bitfields,
159with the added specification that the CTF integer bitfields have a fixed
160binary representation. A MIT-licensed reference implementation of the
161CTF portable bitfields is available at:
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162
163 http://git.efficios.com/?p=babeltrace.git;a=blob;f=include/babeltrace/bitfield.h
164
165Binary representation of integers:
166
167- On little and big endian:
168 - Within a byte, high bits correspond to an integer high bits, and low bits
169 correspond to low bits.
170- On little endian:
171 - Integer across multiple bytes are placed from the less significant to the
172 most significant.
173 - Consecutive integers are placed from lower bits to higher bits (even within
174 a byte).
175- On big endian:
176 - Integer across multiple bytes are placed from the most significant to the
177 less significant.
178 - Consecutive integers are placed from higher bits to lower bits (even within
179 a byte).
180
181This binary representation is derived from the bitfield implementation in GCC
182for little and big endian. However, contrary to what GCC does, integers can
6672e9e1 183cross units boundaries (no padding is required). Padding can be explicitly
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184added (see 4.1.6 GNU/C bitfields) to follow the GCC layout if needed.
185
6672e9e1 186TSDL meta-data representation:
5ba9f198 187
80fd2569 188 integer {
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189 signed = true OR false; /* default false */
190 byte_order = native OR network OR be OR le; /* default native */
191 size = value; /* value in bits, no default */
192 align = value; /* value in bits */
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193 /* based used for pretty-printing output, default: decimal. */
194 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
195 OR octal OR oct OR o OR 8 OR binary OR b OR 2;
2152348f 196 }
5ba9f198 197
80fd2569 198Example of type inheritance (creation of a uint32_t named type):
5ba9f198 199
359894ac 200typealias integer {
9e4e34e9 201 size = 32;
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202 signed = false;
203 align = 32;
38b8da21 204} := uint32_t;
5ba9f198 205
80fd2569 206Definition of a named 5-bit signed bitfield:
5ba9f198 207
359894ac 208typealias integer {
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209 size = 5;
210 signed = true;
211 align = 1;
38b8da21 212} := int5_t;
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213
2144.1.6 GNU/C bitfields
215
216The GNU/C bitfields follow closely the integer representation, with a
217particularity on alignment: if a bitfield cannot fit in the current unit, the
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218unit is padded and the bitfield starts at the following unit. The unit size is
219defined by the size of the type "unit_type".
5ba9f198 220
6672e9e1 221TSDL meta-data representation:
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222
223 unit_type name:size:
224
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225As an example, the following structure declared in C compiled by GCC:
226
227struct example {
228 short a:12;
229 short b:5;
230};
231
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232The example structure is aligned on the largest element (short). The second
233bitfield would be aligned on the next unit boundary, because it would not fit in
234the current unit.
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235
2364.1.7 Floating point
237
6672e9e1 238The floating point values byte ordering is defined in the TSDL meta-data.
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239
240Floating point values follow the IEEE 754-2008 standard interchange formats.
241Description of the floating point values include the exponent and mantissa size
242in bits. Some requirements are imposed on the floating point values:
243
244- FLT_RADIX must be 2.
245- mant_dig is the number of digits represented in the mantissa. It is specified
246 by the ISO C99 standard, section 5.2.4, as FLT_MANT_DIG, DBL_MANT_DIG and
247 LDBL_MANT_DIG as defined by <float.h>.
248- exp_dig is the number of digits represented in the exponent. Given that
249 mant_dig is one bit more than its actual size in bits (leading 1 is not
250 needed) and also given that the sign bit always takes one bit, exp_dig can be
251 specified as:
252
253 - sizeof(float) * CHAR_BIT - FLT_MANT_DIG
254 - sizeof(double) * CHAR_BIT - DBL_MANT_DIG
255 - sizeof(long double) * CHAR_BIT - LDBL_MANT_DIG
256
6672e9e1 257TSDL meta-data representation:
5ba9f198 258
80fd2569 259floating_point {
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260 exp_dig = value;
261 mant_dig = value;
262 byte_order = native OR network OR be OR le;
263 align = value;
2152348f 264}
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265
266Example of type inheritance:
267
359894ac 268typealias floating_point {
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269 exp_dig = 8; /* sizeof(float) * CHAR_BIT - FLT_MANT_DIG */
270 mant_dig = 24; /* FLT_MANT_DIG */
271 byte_order = native;
ec4404a7 272 align = 32;
38b8da21 273} := float;
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274
275TODO: define NaN, +inf, -inf behavior.
276
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277Bit-packed, byte-packed or larger alignments can be used for floating
278point values, similarly to integers.
279
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2804.1.8 Enumerations
281
282Enumerations are a mapping between an integer type and a table of strings. The
283numerical representation of the enumeration follows the integer type specified
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284by the meta-data. The enumeration mapping table is detailed in the enumeration
285description within the meta-data. The mapping table maps inclusive value
286ranges (or single values) to strings. Instead of being limited to simple
3bf79539 287"value -> string" mappings, these enumerations map
80fd2569 288"[ start_value ... end_value ] -> string", which map inclusive ranges of
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289values to strings. An enumeration from the C language can be represented in
290this format by having the same start_value and end_value for each element, which
291is in fact a range of size 1. This single-value range is supported without
4767a9e7 292repeating the start and end values with the value = string declaration.
80fd2569 293
a9b83695 294enum name : integer_type {
359894ac 295 somestring = start_value1 ... end_value1,
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296 "other string" = start_value2 ... end_value2,
297 yet_another_string, /* will be assigned to end_value2 + 1 */
298 "some other string" = value,
299 ...
300};
301
302If the values are omitted, the enumeration starts at 0 and increment of 1 for
303each entry:
304
a9b83695 305enum name : unsigned int {
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306 ZERO,
307 ONE,
308 TWO,
309 TEN = 10,
310 ELEVEN,
3bf79539 311};
5ba9f198 312
80fd2569 313Overlapping ranges within a single enumeration are implementation defined.
5ba9f198 314
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315A nameless enumeration can be declared as a field type or as part of a typedef:
316
a9b83695 317enum : integer_type {
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318 ...
319}
320
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321Enumerations omitting the container type ": integer_type" use the "int"
322type (for compatibility with C99). The "int" type must be previously
323declared. E.g.:
324
325typealias integer { size = 32; align = 32; signed = true } := int;
326
327enum {
328 ...
329}
330
1fad7a85 331
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3324.2 Compound types
333
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334Compound are aggregation of type declarations. Compound types include
335structures, variant, arrays, sequences, and strings.
336
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3374.2.1 Structures
338
339Structures are aligned on the largest alignment required by basic types
340contained within the structure. (This follows the ISO/C standard for structures)
341
6672e9e1 342TSDL meta-data representation of a named structure:
5ba9f198 343
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344struct name {
345 field_type field_name;
346 field_type field_name;
347 ...
348};
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349
350Example:
351
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352struct example {
353 integer { /* Nameless type */
354 size = 16;
355 signed = true;
356 align = 16;
357 } first_field_name;
6672e9e1 358 uint64_t second_field_name; /* Named type declared in the meta-data */
3bf79539 359};
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360
361The fields are placed in a sequence next to each other. They each possess a
362field name, which is a unique identifier within the structure.
363
2152348f 364A nameless structure can be declared as a field type or as part of a typedef:
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365
366struct {
367 ...
2152348f 368}
80fd2569 369
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370Alignment for a structure compound type can be forced to a minimum value
371by adding an "align" specifier after the declaration of a structure
372body. This attribute is read as: align(value). The value is specified in
373bits. The structure will be aligned on the maximum value between this
374attribute and the alignment required by the basic types contained within
375the structure. e.g.
376
377struct {
378 ...
379} align(32)
380
77a98c82 3814.2.2 Variants (Discriminated/Tagged Unions)
fcba70d4 382
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383A CTF variant is a selection between different types. A CTF variant must
384always be defined within the scope of a structure or within fields
385contained within a structure (defined recursively). A "tag" enumeration
386field must appear in either the same lexical scope, prior to the variant
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387field (in field declaration order), in an upper lexical scope (see
388Section 7.3.1), or in an upper dynamic scope (see Section 7.3.2). The
389type selection is indicated by the mapping from the enumeration value to
390the string used as variant type selector. The field to use as tag is
391specified by the "tag_field", specified between "< >" after the
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392"variant" keyword for unnamed variants, and after "variant name" for
393named variants.
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394
395The alignment of the variant is the alignment of the type as selected by the tag
396value for the specific instance of the variant. The alignment of the type
397containing the variant is independent of the variant alignment. The size of the
398variant is the size as selected by the tag value for the specific instance of
399the variant.
400
401A named variant declaration followed by its definition within a structure
402declaration:
403
404variant name {
405 field_type sel1;
406 field_type sel2;
407 field_type sel3;
408 ...
409};
410
411struct {
a9b83695 412 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
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413 ...
414 variant name <tag_field> v;
415}
416
417An unnamed variant definition within a structure is expressed by the following
6672e9e1 418TSDL meta-data:
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419
420struct {
a9b83695 421 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
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422 ...
423 variant <tag_field> {
424 field_type sel1;
425 field_type sel2;
426 field_type sel3;
427 ...
428 } v;
429}
430
431Example of a named variant within a sequence that refers to a single tag field:
432
433variant example {
434 uint32_t a;
435 uint64_t b;
436 short c;
437};
438
439struct {
a9b83695 440 enum : uint2_t { a, b, c } choice;
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441 unsigned int seqlen;
442 variant example <choice> v[seqlen];
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443}
444
445Example of an unnamed variant:
446
447struct {
a9b83695 448 enum : uint2_t { a, b, c, d } choice;
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449 /* Unrelated fields can be added between the variant and its tag */
450 int32_t somevalue;
451 variant <choice> {
452 uint32_t a;
453 uint64_t b;
454 short c;
455 struct {
456 unsigned int field1;
457 uint64_t field2;
458 } d;
459 } s;
460}
461
462Example of an unnamed variant within an array:
463
464struct {
a9b83695 465 enum : uint2_t { a, b, c } choice;
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466 variant <choice> {
467 uint32_t a;
468 uint64_t b;
469 short c;
15850440 470 } v[10];
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471}
472
473Example of a variant type definition within a structure, where the defined type
474is then declared within an array of structures. This variant refers to a tag
475located in an upper lexical scope. This example clearly shows that a variant
476type definition referring to the tag "x" uses the closest preceding field from
477the lexical scope of the type definition.
478
479struct {
a9b83695 480 enum : uint2_t { a, b, c, d } x;
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481
482 typedef variant <x> { /*
483 * "x" refers to the preceding "x" enumeration in the
484 * lexical scope of the type definition.
485 */
486 uint32_t a;
487 uint64_t b;
488 short c;
489 } example_variant;
490
491 struct {
a9b83695 492 enum : int { x, y, z } x; /* This enumeration is not used by "v". */
fcba70d4 493 example_variant v; /*
a9b83695 494 * "v" uses the "enum : uint2_t { a, b, c, d }"
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495 * tag.
496 */
497 } a[10];
498}
499
5004.2.3 Arrays
5ba9f198 501
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502Arrays are fixed-length. Their length is declared in the type
503declaration within the meta-data. They contain an array of "inner type"
504elements, which can refer to any type not containing the type of the
505array being declared (no circular dependency). The length is the number
506of elements in an array.
5ba9f198 507
6672e9e1 508TSDL meta-data representation of a named array:
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509
510typedef elem_type name[length];
5ba9f198 511
2152348f 512A nameless array can be declared as a field type within a structure, e.g.:
5ba9f198 513
2152348f 514 uint8_t field_name[10];
80fd2569 515
ec4404a7 516Arrays are always aligned on their element alignment requirement.
5ba9f198 517
fcba70d4 5184.2.4 Sequences
5ba9f198 519
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520Sequences are dynamically-sized arrays. They refer to a a "length"
521unsigned integer field, which must appear in either the same lexical scope,
522prior to the sequence field (in field declaration order), in an upper
523lexical scope (see Section 7.3.1), or in an upper dynamic scope (see
524Section 7.3.2). This length field represents the number of elements in
525the sequence. The sequence per se is an array of "inner type" elements.
5ba9f198 526
1ab22b2a 527TSDL meta-data representation for a sequence type definition:
80fd2569 528
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529struct {
530 unsigned int length_field;
531 typedef elem_type typename[length_field];
532 typename seq_field_name;
533}
534
535A sequence can also be declared as a field type, e.g.:
80fd2569 536
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537struct {
538 unsigned int length_field;
539 long seq_field_name[length_field];
540}
80fd2569 541
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542Multiple sequences can refer to the same length field, and these length
543fields can be in a different upper dynamic scope:
544
545e.g., assuming the stream.event.header defines:
546
547stream {
548 ...
549 id = 1;
550 event.header := struct {
551 uint16_t seq_len;
552 };
553};
554
555event {
556 ...
557 stream_id = 1;
558 fields := struct {
559 long seq_a[stream.event.header.seq_len];
560 char seq_b[stream.event.header.seq_len];
561 };
562};
80fd2569 563
1ab22b2a 564The sequence elements follow the "array" specifications.
5ba9f198 565
fcba70d4 5664.2.5 Strings
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567
568Strings are an array of bytes of variable size and are terminated by a '\0'
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569"NULL" character. Their encoding is described in the TSDL meta-data. In
570absence of encoding attribute information, the default encoding is
571UTF-8.
5ba9f198 572
6672e9e1 573TSDL meta-data representation of a named string type:
80fd2569 574
359894ac 575typealias string {
5ba9f198 576 encoding = UTF8 OR ASCII;
38b8da21 577} := name;
5ba9f198 578
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579A nameless string type can be declared as a field type:
580
581string field_name; /* Use default UTF8 encoding */
5ba9f198 582
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583Strings are always aligned on byte size.
584
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5855. Event Packet Header
586
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587The event packet header consists of two parts: the "event packet header"
588is the same for all streams of a trace. The second part, the "event
589packet context", is described on a per-stream basis. Both are described
590in the TSDL meta-data. The packets are aligned on architecture-page-sized
591addresses.
3bf79539 592
6672e9e1 593Event packet header (all fields are optional, specified by TSDL meta-data):
3bf79539 594
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595- Magic number (CTF magic number: 0xC1FC1FC1) specifies that this is a
596 CTF packet. This magic number is optional, but when present, it should
597 come at the very beginning of the packet.
598- Trace UUID, used to ensure the event packet match the meta-data used.
599 (note: we cannot use a meta-data checksum in every cases instead of a
600 UUID because meta-data can be appended to while tracing is active)
601 This field is optional.
602- Stream ID, used as reference to stream description in meta-data.
603 This field is optional if there is only one stream description in the
604 meta-data, but becomes required if there are more than one stream in
605 the TSDL meta-data description.
3bf79539 606
6672e9e1 607Event packet context (all fields are optional, specified by TSDL meta-data):
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608
609- Event packet content size (in bytes).
610- Event packet size (in bytes, includes padding).
611- Event packet content checksum (optional). Checksum excludes the event packet
612 header.
613- Per-stream event packet sequence count (to deal with UDP packet loss). The
614 number of significant sequence counter bits should also be present, so
b11853af 615 wrap-arounds are dealt with correctly.
6672e9e1 616- Time-stamp at the beginning and time-stamp at the end of the event packet.
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617 Both timestamps are written in the packet header, but sampled respectively
618 while (or before) writing the first event and while (or after) writing the
619 last event in the packet. The inclusive range between these timestamps should
620 include all event timestamps assigned to events contained within the packet.
5ba9f198 621- Events discarded count
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622 - Snapshot of a per-stream free-running counter, counting the number of
623 events discarded that were supposed to be written in the stream prior to
624 the first event in the event packet.
5ba9f198 625 * Note: producer-consumer buffer full condition should fill the current
3bf79539 626 event packet with padding so we know exactly where events have been
5ba9f198 627 discarded.
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628- Lossless compression scheme used for the event packet content. Applied
629 directly to raw data. New types of compression can be added in following
630 versions of the format.
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631 0: no compression scheme
632 1: bzip2
633 2: gzip
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634 3: xz
635- Cypher used for the event packet content. Applied after compression.
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636 0: no encryption
637 1: AES
3bf79539 638- Checksum scheme used for the event packet content. Applied after encryption.
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639 0: no checksum
640 1: md5
641 2: sha1
642 3: crc32
643
6672e9e1 6445.1 Event Packet Header Description
3bf79539 645
fc5425db 646The event packet header layout is indicated by the trace packet.header
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647field. Here is a recommended structure type for the packet header with
648the fields typically expected (although these fields are each optional):
fc5425db 649
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650struct event_packet_header {
651 uint32_t magic;
3fde5da1 652 uint8_t uuid[16];
3bf79539 653 uint32_t stream_id;
80fd2569 654};
5ba9f198 655
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656trace {
657 ...
658 packet.header := struct event_packet_header;
659};
660
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661If the magic number is not present, tools such as "file" will have no
662mean to discover the file type.
663
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664If the uuid is not present, no validation that the meta-data actually
665corresponds to the stream is performed.
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666
667If the stream_id packet header field is missing, the trace can only
668contain a single stream. Its "id" field can be left out, and its events
669don't need to declare a "stream_id" field.
670
671
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6725.2 Event Packet Context Description
673
674Event packet context example. These are declared within the stream declaration
6672e9e1 675in the meta-data. All these fields are optional. If the packet size field is
6a7c61df 676missing, the whole stream only contains a single packet. If the content
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677size field is missing, the packet is filled (no padding). The content
678and packet sizes include all headers.
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679
680An example event packet context type:
681
80fd2569 682struct event_packet_context {
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683 uint64_t timestamp_begin;
684 uint64_t timestamp_end;
685 uint32_t checksum;
686 uint32_t stream_packet_count;
687 uint32_t events_discarded;
688 uint32_t cpu_id;
689 uint32_t/uint16_t content_size;
690 uint32_t/uint16_t packet_size;
691 uint8_t stream_packet_count_bits; /* Significant counter bits */
692 uint8_t compression_scheme;
693 uint8_t encryption_scheme;
3b0f8e4d 694 uint8_t checksum_scheme;
3bf79539 695};
5ba9f198 696
fcba70d4 697
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6986. Event Structure
699
700The overall structure of an event is:
701
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7021 - Stream Packet Context (as specified by the stream meta-data)
703 2 - Event Header (as specified by the stream meta-data)
704 3 - Stream Event Context (as specified by the stream meta-data)
705 4 - Event Context (as specified by the event meta-data)
706 5 - Event Payload (as specified by the event meta-data)
5ba9f198 707
fdf2bb05 708This structure defines an implicit dynamic scoping, where variants
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709located in inner structures (those with a higher number in the listing
710above) can refer to the fields of outer structures (with lower number in
6c7226e9 711the listing above). See Section 7.3 TSDL Scopes for more detail.
5ba9f198 712
fdf2bb05 7136.1 Event Header
fcba70d4 714
6672e9e1 715Event headers can be described within the meta-data. We hereby propose, as an
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716example, two types of events headers. Type 1 accommodates streams with less than
71731 event IDs. Type 2 accommodates streams with 31 or more event IDs.
5ba9f198 718
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719One major factor can vary between streams: the number of event IDs assigned to
720a stream. Luckily, this information tends to stay relatively constant (modulo
5ba9f198 721event registration while trace is being recorded), so we can specify different
3bf79539 722representations for streams containing few event IDs and streams containing
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723many event IDs, so we end up representing the event ID and time-stamp as
724densely as possible in each case.
5ba9f198 725
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726The header is extended in the rare occasions where the information cannot be
727represented in the ranges available in the standard event header. They are also
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728used in the rare occasions where the data required for a field could not be
729collected: the flag corresponding to the missing field within the missing_fields
730array is then set to 1.
5ba9f198 731
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732Types uintX_t represent an X-bit unsigned integer, as declared with
733either:
5ba9f198 734
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735 typealias integer { size = X; align = X; signed = false } := uintX_t;
736
737 or
738
739 typealias integer { size = X; align = 1; signed = false } := uintX_t;
5ba9f198 740
fdf2bb05 7416.1.1 Type 1 - Few event IDs
5ba9f198
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742
743 - Aligned on 32-bit (or 8-bit if byte-packed, depending on the architecture
744 preference).
5ba9f198 745 - Native architecture byte ordering.
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746 - For "compact" selection
747 - Fixed size: 32 bits.
748 - For "extended" selection
749 - Size depends on the architecture and variant alignment.
5ba9f198 750
80fd2569 751struct event_header_1 {
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752 /*
753 * id: range: 0 - 30.
754 * id 31 is reserved to indicate an extended header.
755 */
a9b83695 756 enum : uint5_t { compact = 0 ... 30, extended = 31 } id;
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757 variant <id> {
758 struct {
759 uint27_t timestamp;
760 } compact;
761 struct {
762 uint32_t id; /* 32-bit event IDs */
763 uint64_t timestamp; /* 64-bit timestamps */
764 } extended;
765 } v;
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766};
767
5ba9f198 768
fdf2bb05 7696.1.2 Type 2 - Many event IDs
5ba9f198 770
fcba70d4 771 - Aligned on 16-bit (or 8-bit if byte-packed, depending on the architecture
5ba9f198 772 preference).
5ba9f198 773 - Native architecture byte ordering.
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774 - For "compact" selection
775 - Size depends on the architecture and variant alignment.
776 - For "extended" selection
777 - Size depends on the architecture and variant alignment.
5ba9f198 778
80fd2569 779struct event_header_2 {
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780 /*
781 * id: range: 0 - 65534.
782 * id 65535 is reserved to indicate an extended header.
783 */
a9b83695 784 enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;
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785 variant <id> {
786 struct {
787 uint32_t timestamp;
788 } compact;
789 struct {
790 uint32_t id; /* 32-bit event IDs */
791 uint64_t timestamp; /* 64-bit timestamps */
792 } extended;
793 } v;
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794};
795
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796
7976.2 Event Context
798
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799The event context contains information relative to the current event.
800The choice and meaning of this information is specified by the TSDL
801stream and event meta-data descriptions. The stream context is applied
802to all events within the stream. The stream context structure follows
803the event header. The event context is applied to specific events. Its
804structure follows the stream context structure.
5ba9f198 805
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806An example of stream-level event context is to save the event payload size with
807each event, or to save the current PID with each event. These are declared
6672e9e1 808within the stream declaration within the meta-data:
5ba9f198 809
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810 stream {
811 ...
6672e9e1 812 event.context := struct {
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813 uint pid;
814 uint16_t payload_size;
6672e9e1 815 };
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816 };
817
818An example of event-specific event context is to declare a bitmap of missing
819fields, only appended after the stream event context if the extended event
820header is selected. NR_FIELDS is the number of fields within the event (a
821numeric value).
5ba9f198 822
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823 event {
824 context = struct {
825 variant <id> {
826 struct { } compact;
827 struct {
828 uint1_t missing_fields[NR_FIELDS]; /* missing event fields bitmap */
829 } extended;
830 } v;
831 };
832 ...
833 }
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834
8356.3 Event Payload
836
837An event payload contains fields specific to a given event type. The fields
6672e9e1 838belonging to an event type are described in the event-specific meta-data
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839within a structure type.
840
8416.3.1 Padding
842
843No padding at the end of the event payload. This differs from the ISO/C standard
844for structures, but follows the CTF standard for structures. In a trace, even
845though it makes sense to align the beginning of a structure, it really makes no
846sense to add padding at the end of the structure, because structures are usually
847not followed by a structure of the same type.
848
849This trick can be done by adding a zero-length "end" field at the end of the C
850structures, and by using the offset of this field rather than using sizeof()
3bf79539 851when calculating the size of a structure (see Appendix "A. Helper macros").
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852
8536.3.2 Alignment
854
855The event payload is aligned on the largest alignment required by types
856contained within the payload. (This follows the ISO/C standard for structures)
857
858
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8597. Trace Stream Description Language (TSDL)
860
861The Trace Stream Description Language (TSDL) allows expression of the
862binary trace streams layout in a C99-like Domain Specific Language
863(DSL).
864
865
6672e9e1 8667.1 Meta-data
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867
868The trace stream layout description is located in the trace meta-data.
869The meta-data is itself located in a stream identified by its name:
870"metadata".
5ba9f198 871
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872The meta-data description can be expressed in two different formats:
873text-only and packet-based. The text-only description facilitates
874generation of meta-data and provides a convenient way to enter the
875meta-data information by hand. The packet-based meta-data provides the
876CTF stream packet facilities (checksumming, compression, encryption,
877network-readiness) for meta-data stream generated and transported by a
878tracer.
879
880The text-only meta-data file is a plain text TSDL description.
881
882The packet-based meta-data is made of "meta-data packets", which each
883start with a meta-data packet header. The packet-based meta-data
884description is detected by reading the magic number "0x75D11D57" at the
885beginning of the file. This magic number is also used to detect the
886endianness of the architecture by trying to read the CTF magic number
887and its counterpart in reversed endianness. The events within the
888meta-data stream have no event header nor event context. Each event only
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889contains a "sequence" payload, which is a sequence of bits using the
890"trace.packet.header.content_size" field as a placeholder for its
891length. The formatting of this sequence of bits is a plain-text
892representation of the TSDL description. Each meta-data packet start with
893a special packet header, specific to the meta-data stream, which
894contains, exactly:
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895
896struct metadata_packet_header {
2daeaa3a 897 uint32_t magic; /* 0x75D11D57 */
3fde5da1 898 uint8_t uuid[16]; /* Unique Universal Identifier */
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899 uint32_t checksum; /* 0 if unused */
900 uint32_t content_size; /* in bits */
901 uint32_t packet_size; /* in bits */
902 uint8_t compression_scheme; /* 0 if unused */
903 uint8_t encryption_scheme; /* 0 if unused */
904 uint8_t checksum_scheme; /* 0 if unused */
905};
906
907The packet-based meta-data can be converted to a text-only meta-data by
908concatenating all the strings in contains.
4fafe1ad 909
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910In the textual representation of the meta-data, the text contained
911within "/*" and "*/", as well as within "//" and end of line, are
912treated as comments. Boolean values can be represented as true, TRUE,
913or 1 for true, and false, FALSE, or 0 for false. Within the string-based
914meta-data description, the trace UUID is represented as a string of
915hexadecimal digits and dashes "-". In the event packet header, the trace
916UUID is represented as an array of bytes.
fcba70d4 917
fdf2bb05 918
6c7226e9 9197.2 Declaration vs Definition
fdf2bb05
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920
921A declaration associates a layout to a type, without specifying where
922this type is located in the event structure hierarchy (see Section 6).
923This therefore includes typedef, typealias, as well as all type
924specifiers. In certain circumstances (typedef, structure field and
925variant field), a declaration is followed by a declarator, which specify
926the newly defined type name (for typedef), or the field name (for
927declarations located within structure and variants). Array and sequence,
928declared with square brackets ("[" "]"), are part of the declarator,
a9b83695 929similarly to C99. The enumeration base type is specified by
6c7226e9 930": enum_base", which is part of the type specifier. The variant tag
a9b83695 931name, specified between "<" ">", is also part of the type specifier.
fdf2bb05
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932
933A definition associates a type to a location in the event structure
b9606a77
MD
934hierarchy (see Section 6). This association is denoted by ":=", as shown
935in Section 7.3.
fdf2bb05
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936
937
6c7226e9 9387.3 TSDL Scopes
fdf2bb05 939
6c7226e9
MD
940TSDL uses two different types of scoping: a lexical scope is used for
941declarations and type definitions, and a dynamic scope is used for
2e7d7fcb
MD
942variants references to tag fields and for sequence references to length
943fields.
fdf2bb05 944
6c7226e9 9457.3.1 Lexical Scope
fdf2bb05 946
d285084f
MD
947Each of "trace", "stream", "event", "struct" and "variant" have their own
948nestable declaration scope, within which types can be declared using "typedef"
fdf2bb05 949and "typealias". A root declaration scope also contains all declarations
7d9d7e92 950located outside of any of the aforementioned declarations. An inner
fdf2bb05 951declaration scope can refer to type declared within its container
7d9d7e92
MD
952lexical scope prior to the inner declaration scope. Redefinition of a
953typedef or typealias is not valid, although hiding an upper scope
fdf2bb05
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954typedef or typealias is allowed within a sub-scope.
955
6c7226e9 9567.3.2 Dynamic Scope
fdf2bb05 957
7d9d7e92
MD
958A dynamic scope consists in the lexical scope augmented with the
959implicit event structure definition hierarchy presented at Section 6.
2e7d7fcb
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960The dynamic scope is used for variant tag and sequence length
961definitions. It is used at definition time to look up the location of
962the tag field associated with a variant, and to lookup up the location
963of the length field associated with a sequence.
964
965Therefore, variants (or sequences) in lower levels in the dynamic scope
966(e.g. event context) can refer to a tag (or length) field located in
967upper levels (e.g. in the event header) by specifying, in this case, the
968associated tag with <header.field_name>. This allows, for instance, the
969event context to define a variant referring to the "id" field of the
970event header as selector.
fdf2bb05
MD
971
972The target dynamic scope must be specified explicitly when referring to
973a field outside of the local static scope. The dynamic scope prefixes
974are thus:
975
e0d9e2c7 976 - Trace Packet Header: <trace.packet.header. >,
7d9d7e92
MD
977 - Stream Packet Context: <stream.packet.context. >,
978 - Event Header: <stream.event.header. >,
979 - Stream Event Context: <stream.event.context. >,
980 - Event Context: <event.context. >,
981 - Event Payload: <event.fields. >.
fdf2bb05
MD
982
983Multiple declarations of the same field name within a single scope is
984not valid. It is however valid to re-use the same field name in
985different scopes. There is no possible conflict, because the dynamic
986scope must be specified when a variant refers to a tag field located in
987a different dynamic scope.
988
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989The information available in the dynamic scopes can be thought of as the
990current tracing context. At trace production, information about the
991current context is saved into the specified scope field levels. At trace
992consumption, for each event, the current trace context is therefore
993readable by accessing the upper dynamic scopes.
994
fdf2bb05 995
6c7226e9 9967.4 TSDL Examples
d285084f 997
6672e9e1 998The grammar representing the TSDL meta-data is presented in Appendix C.
7df6b93a 999TSDL Grammar. This section presents a rather lighter reading that
6672e9e1 1000consists in examples of TSDL meta-data, with template values.
969f30c0 1001
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MD
1002The stream "id" can be left out if there is only one stream in the
1003trace. The event "id" field can be left out if there is only one event
1004in a stream.
1005
5ba9f198 1006trace {
fdf2bb05 1007 major = value; /* Trace format version */
5ba9f198 1008 minor = value;
fdf2bb05 1009 uuid = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"; /* Trace UUID */
58997e9e 1010 byte_order = be OR le; /* Endianness (required) */
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1011 packet.header := struct {
1012 uint32_t magic;
3fde5da1 1013 uint8_t uuid[16];
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MD
1014 uint32_t stream_id;
1015 };
3bf79539 1016};
5ba9f198 1017
3bf79539
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1018stream {
1019 id = stream_id;
fdf2bb05 1020 /* Type 1 - Few event IDs; Type 2 - Many event IDs. See section 6.1. */
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MD
1021 event.header := event_header_1 OR event_header_2;
1022 event.context := struct {
77a98c82 1023 ...
3bf79539 1024 };
4fa992a5 1025 packet.context := struct {
77a98c82 1026 ...
3bf79539
MD
1027 };
1028};
5ba9f198
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1029
1030event {
3d13ef1a 1031 name = event_name;
3bf79539 1032 id = value; /* Numeric identifier within the stream */
67f02e24 1033 stream_id = stream_id;
4fa992a5 1034 context := struct {
fcba70d4
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1035 ...
1036 };
4fa992a5 1037 fields := struct {
80fd2569
MD
1038 ...
1039 };
3bf79539 1040};
5ba9f198
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1041
1042/* More detail on types in section 4. Types */
1043
3d13ef1a
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1044/*
1045 * Named types:
1046 *
4fa992a5 1047 * Type declarations behave similarly to the C standard.
3d13ef1a
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1048 */
1049
80af8ac6 1050typedef aliased_type_specifiers new_type_declarators;
2152348f 1051
3d13ef1a 1052/* e.g.: typedef struct example new_type_name[10]; */
80fd2569 1053
4fa992a5
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1054/*
1055 * typealias
1056 *
1057 * The "typealias" declaration can be used to give a name (including
80af8ac6
MD
1058 * pointer declarator specifier) to a type. It should also be used to
1059 * map basic C types (float, int, unsigned long, ...) to a CTF type.
1060 * Typealias is a superset of "typedef": it also allows assignment of a
38b8da21 1061 * simple variable identifier to a type.
4fa992a5
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1062 */
1063
1064typealias type_class {
80fd2569 1065 ...
38b8da21 1066} := type_specifiers type_declarator;
2152348f 1067
3d13ef1a
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1068/*
1069 * e.g.:
4fa992a5 1070 * typealias integer {
3d13ef1a
MD
1071 * size = 32;
1072 * align = 32;
1073 * signed = false;
38b8da21 1074 * } := struct page *;
359894ac
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1075 *
1076 * typealias integer {
1077 * size = 32;
1078 * align = 32;
1079 * signed = true;
38b8da21 1080 * } := int;
3d13ef1a 1081 */
80fd2569
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1082
1083struct name {
3bf79539
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1084 ...
1085};
5ba9f198 1086
fcba70d4
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1087variant name {
1088 ...
1089};
1090
a9b83695 1091enum name : integer_type {
3bf79539
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1092 ...
1093};
1094
2152348f 1095
4fa992a5
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1096/*
1097 * Unnamed types, contained within compound type fields, typedef or typealias.
1098 */
2152348f 1099
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1100struct {
1101 ...
2152348f 1102}
5ba9f198 1103
ec4404a7
MD
1104struct {
1105 ...
1106} align(value)
1107
fcba70d4
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1108variant {
1109 ...
1110}
1111
a9b83695 1112enum : integer_type {
80fd2569 1113 ...
2152348f
MD
1114}
1115
1116typedef type new_type[length];
3bf79539 1117
2152348f
MD
1118struct {
1119 type field_name[length];
1120}
1121
1122typedef type new_type[length_type];
1123
1124struct {
1125 type field_name[length_type];
1126}
1127
1128integer {
80fd2569 1129 ...
2152348f 1130}
3bf79539 1131
2152348f 1132floating_point {
80fd2569 1133 ...
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MD
1134}
1135
1136struct {
1137 integer_type field_name:size; /* GNU/C bitfield */
1138}
1139
1140struct {
1141 string field_name;
1142}
3bf79539 1143
fcba70d4 1144
3bf79539 1145A. Helper macros
5ba9f198
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1146
1147The two following macros keep track of the size of a GNU/C structure without
1148padding at the end by placing HEADER_END as the last field. A one byte end field
1149is used for C90 compatibility (C99 flexible arrays could be used here). Note
1150that this does not affect the effective structure size, which should always be
1151calculated with the header_sizeof() helper.
1152
1153#define HEADER_END char end_field
1154#define header_sizeof(type) offsetof(typeof(type), end_field)
3bf79539
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1155
1156
1157B. Stream Header Rationale
1158
1159An event stream is divided in contiguous event packets of variable size. These
1160subdivisions allow the trace analyzer to perform a fast binary search by time
1161within the stream (typically requiring to index only the event packet headers)
1162without reading the whole stream. These subdivisions have a variable size to
1163eliminate the need to transfer the event packet padding when partially filled
1164event packets must be sent when streaming a trace for live viewing/analysis.
1165An event packet can contain a certain amount of padding at the end. Dividing
1166streams into event packets is also useful for network streaming over UDP and
1167flight recorder mode tracing (a whole event packet can be swapped out of the
1168buffer atomically for reading).
1169
1170The stream header is repeated at the beginning of each event packet to allow
1171flexibility in terms of:
1172
1173 - streaming support,
1174 - allowing arbitrary buffers to be discarded without making the trace
1175 unreadable,
1176 - allow UDP packet loss handling by either dealing with missing event packet
1177 or asking for re-transmission.
1178 - transparently support flight recorder mode,
1179 - transparently support crash dump.
1180
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1181
1182C. TSDL Grammar
fcba70d4 1183
4fa992a5 1184/*
6c7226e9 1185 * Common Trace Format (CTF) Trace Stream Description Language (TSDL) Grammar.
4fa992a5
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1186 *
1187 * Inspired from the C99 grammar:
1188 * http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf (Annex A)
6c7226e9
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1189 * and c++1x grammar (draft)
1190 * http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3291.pdf (Annex A)
4fa992a5
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1191 *
1192 * Specialized for CTF needs by including only constant and declarations from
1193 * C99 (excluding function declarations), and by adding support for variants,
6c7226e9
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1194 * sequences and CTF-specific specifiers. Enumeration container types
1195 * semantic is inspired from c++1x enum-base.
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1196 */
1197
11981) Lexical grammar
1199
12001.1) Lexical elements
1201
1202token:
1203 keyword
1204 identifier
1205 constant
1206 string-literal
1207 punctuator
1208
12091.2) Keywords
1210
1211keyword: is one of
1212
ec4404a7 1213align
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1214const
1215char
1216double
1217enum
1218event
1219floating_point
1220float
1221integer
1222int
1223long
1224short
1225signed
1226stream
1227string
1228struct
1229trace
3e1e1a78 1230typealias
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1231typedef
1232unsigned
1233variant
1234void
1235_Bool
1236_Complex
1237_Imaginary
1238
1239
12401.3) Identifiers
1241
1242identifier:
1243 identifier-nondigit
1244 identifier identifier-nondigit
1245 identifier digit
1246
1247identifier-nondigit:
1248 nondigit
1249 universal-character-name
1250 any other implementation-defined characters
1251
1252nondigit:
1253 _
1254 [a-zA-Z] /* regular expression */
1255
1256digit:
1257 [0-9] /* regular expression */
1258
12591.4) Universal character names
1260
1261universal-character-name:
1262 \u hex-quad
1263 \U hex-quad hex-quad
1264
1265hex-quad:
1266 hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
1267
12681.5) Constants
1269
1270constant:
1271 integer-constant
1272 enumeration-constant
1273 character-constant
1274
1275integer-constant:
1276 decimal-constant integer-suffix-opt
1277 octal-constant integer-suffix-opt
1278 hexadecimal-constant integer-suffix-opt
1279
1280decimal-constant:
1281 nonzero-digit
1282 decimal-constant digit
1283
1284octal-constant:
1285 0
1286 octal-constant octal-digit
1287
1288hexadecimal-constant:
1289 hexadecimal-prefix hexadecimal-digit
1290 hexadecimal-constant hexadecimal-digit
1291
1292hexadecimal-prefix:
1293 0x
1294 0X
1295
1296nonzero-digit:
1297 [1-9]
1298
1299integer-suffix:
1300 unsigned-suffix long-suffix-opt
1301 unsigned-suffix long-long-suffix
1302 long-suffix unsigned-suffix-opt
1303 long-long-suffix unsigned-suffix-opt
1304
1305unsigned-suffix:
1306 u
1307 U
1308
1309long-suffix:
1310 l
1311 L
1312
1313long-long-suffix:
1314 ll
1315 LL
1316
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1317enumeration-constant:
1318 identifier
1319 string-literal
1320
1321character-constant:
1322 ' c-char-sequence '
1323 L' c-char-sequence '
1324
1325c-char-sequence:
1326 c-char
1327 c-char-sequence c-char
1328
1329c-char:
1330 any member of source charset except single-quote ('), backslash
1331 (\), or new-line character.
1332 escape-sequence
1333
1334escape-sequence:
1335 simple-escape-sequence
1336 octal-escape-sequence
1337 hexadecimal-escape-sequence
1338 universal-character-name
1339
1340simple-escape-sequence: one of
1341 \' \" \? \\ \a \b \f \n \r \t \v
1342
1343octal-escape-sequence:
1344 \ octal-digit
1345 \ octal-digit octal-digit
1346 \ octal-digit octal-digit octal-digit
1347
1348hexadecimal-escape-sequence:
1349 \x hexadecimal-digit
1350 hexadecimal-escape-sequence hexadecimal-digit
1351
13521.6) String literals
1353
1354string-literal:
1355 " s-char-sequence-opt "
1356 L" s-char-sequence-opt "
1357
1358s-char-sequence:
1359 s-char
1360 s-char-sequence s-char
1361
1362s-char:
1363 any member of source charset except double-quote ("), backslash
1364 (\), or new-line character.
1365 escape-sequence
1366
13671.7) Punctuators
1368
1369punctuator: one of
1370 [ ] ( ) { } . -> * + - < > : ; ... = ,
1371
1372
13732) Phrase structure grammar
1374
1375primary-expression:
1376 identifier
1377 constant
1378 string-literal
1379 ( unary-expression )
1380
1381postfix-expression:
1382 primary-expression
1383 postfix-expression [ unary-expression ]
1384 postfix-expression . identifier
1385 postfix-expressoin -> identifier
1386
1387unary-expression:
1388 postfix-expression
1389 unary-operator postfix-expression
1390
1391unary-operator: one of
1392 + -
1393
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1394assignment-operator:
1395 =
1396
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1397type-assignment-operator:
1398 :=
1399
4fa992a5 1400constant-expression-range:
73d61ac3 1401 unary-expression ... unary-expression
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1402
14032.2) Declarations:
1404
1405declaration:
689e04b4 1406 declaration-specifiers declarator-list-opt ;
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1407 ctf-specifier ;
1408
1409declaration-specifiers:
689e04b4 1410 storage-class-specifier declaration-specifiers-opt
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1411 type-specifier declaration-specifiers-opt
1412 type-qualifier declaration-specifiers-opt
1413
1414declarator-list:
1415 declarator
1416 declarator-list , declarator
1417
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1418abstract-declarator-list:
1419 abstract-declarator
1420 abstract-declarator-list , abstract-declarator
1421
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1422storage-class-specifier:
1423 typedef
1424
1425type-specifier:
1426 void
1427 char
1428 short
1429 int
1430 long
1431 float
1432 double
1433 signed
1434 unsigned
1435 _Bool
1436 _Complex
cfdd51ec 1437 _Imaginary
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1438 struct-specifier
1439 variant-specifier
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1440 enum-specifier
1441 typedef-name
1442 ctf-type-specifier
1443
ec4404a7 1444align-attribute:
73d61ac3 1445 align ( unary-expression )
ec4404a7 1446
4fa992a5 1447struct-specifier:
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1448 struct identifier-opt { struct-or-variant-declaration-list-opt } align-attribute-opt
1449 struct identifier align-attribute-opt
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1450
1451struct-or-variant-declaration-list:
1452 struct-or-variant-declaration
1453 struct-or-variant-declaration-list struct-or-variant-declaration
1454
1455struct-or-variant-declaration:
1456 specifier-qualifier-list struct-or-variant-declarator-list ;
eacb16d1 1457 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list ;
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1458 typealias declaration-specifiers abstract-declarator-list := declaration-specifiers abstract-declarator-list ;
1459 typealias declaration-specifiers abstract-declarator-list := declarator-list ;
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1460
1461specifier-qualifier-list:
1462 type-specifier specifier-qualifier-list-opt
1463 type-qualifier specifier-qualifier-list-opt
1464
1465struct-or-variant-declarator-list:
1466 struct-or-variant-declarator
1467 struct-or-variant-declarator-list , struct-or-variant-declarator
1468
1469struct-or-variant-declarator:
1470 declarator
73d61ac3 1471 declarator-opt : unary-expression
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1472
1473variant-specifier:
1474 variant identifier-opt variant-tag-opt { struct-or-variant-declaration-list }
1475 variant identifier variant-tag
1476
1477variant-tag:
1478 < identifier >
1479
1480enum-specifier:
1481 enum identifier-opt { enumerator-list }
1482 enum identifier-opt { enumerator-list , }
1483 enum identifier
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1484 enum identifier-opt : declaration-specifiers { enumerator-list }
1485 enum identifier-opt : declaration-specifiers { enumerator-list , }
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1486
1487enumerator-list:
1488 enumerator
1489 enumerator-list , enumerator
1490
1491enumerator:
1492 enumeration-constant
73d61ac3 1493 enumeration-constant = unary-expression
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1494 enumeration-constant = constant-expression-range
1495
1496type-qualifier:
1497 const
1498
1499declarator:
1500 pointer-opt direct-declarator
1501
1502direct-declarator:
1503 identifier
1504 ( declarator )
1ab22b2a 1505 direct-declarator [ unary-expression ]
4fa992a5 1506
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1507abstract-declarator:
1508 pointer-opt direct-abstract-declarator
1509
1510direct-abstract-declarator:
1511 identifier-opt
1512 ( abstract-declarator )
1ab22b2a 1513 direct-abstract-declarator [ unary-expression ]
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1514 direct-abstract-declarator [ ]
1515
4fa992a5 1516pointer:
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1517 * type-qualifier-list-opt
1518 * type-qualifier-list-opt pointer
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1519
1520type-qualifier-list:
1521 type-qualifier
1522 type-qualifier-list type-qualifier
1523
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1524typedef-name:
1525 identifier
1526
15272.3) CTF-specific declarations
1528
1529ctf-specifier:
1530 event { ctf-assignment-expression-list-opt }
1531 stream { ctf-assignment-expression-list-opt }
1532 trace { ctf-assignment-expression-list-opt }
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1533 typealias declaration-specifiers abstract-declarator-list := declaration-specifiers abstract-declarator-list ;
1534 typealias declaration-specifiers abstract-declarator-list := declarator-list ;
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1535
1536ctf-type-specifier:
1537 floating_point { ctf-assignment-expression-list-opt }
1538 integer { ctf-assignment-expression-list-opt }
1539 string { ctf-assignment-expression-list-opt }
1540
1541ctf-assignment-expression-list:
1542 ctf-assignment-expression
1543 ctf-assignment-expression-list ; ctf-assignment-expression
1544
1545ctf-assignment-expression:
1546 unary-expression assignment-operator unary-expression
1547 unary-expression type-assignment-operator type-specifier
eacb16d1 1548 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list
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1549 typealias declaration-specifiers abstract-declarator-list := declaration-specifiers abstract-declarator-list
1550 typealias declaration-specifiers abstract-declarator-list := declarator-list
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