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34 .Nd Architecture-specific details
36 Differences between CPU architectures and platforms supported by
39 This document is a quick reference of key ABI details of
42 For full details consult the processor-specific ABI supplement
45 If not explicitly mentioned, sizes are in bytes.
46 The architecture details in this document apply to
48 and later, unless otherwise noted.
51 uses a flat address space.
57 and pointers all have the same representation.
59 In order to maximize compatibility with future pointer integrity mechanisms,
60 manipulations of pointers as integers should be performed via
71 On some architectures, e.g.,
76 the kernel uses a separate address space.
77 On other architectures, kernel and a user mode process share a
79 The kernel is located at the highest addresses.
81 On each architecture, the main user mode thread's stack starts near
82 the highest user address and grows down.
85 architecture support varies by release.
86 This table shows the first
88 release to support each architecture, and, for discontinued
89 architectures, the final release.
91 .Bl -column -offset indent "Sy Architecture" "Sy Initial Release" "Sy Final Release"
92 .It Sy Architecture Ta Sy Initial Release Ta Sy Final Release
94 .It alpha Ta 3.2 Ta 6.4
96 .It arm Ta 6.0 Ta 12.x
97 .It armeb Ta 8.0 Ta 11.x
100 .It ia64 Ta 5.0 Ta 10.4
109 .It mips64elhf Ta 12.0
111 .It pc98 Ta 2.2 Ta 11.x
113 .It powerpcspe Ta 12.0
116 .It riscv64sf Ta 12.0
117 .It sparc64 Ta 5.0 Ta 12.x
122 architectures use some variant of the ELF (see
124 .Sy Application Binary Interface
125 (ABI) for the machine processor.
126 All supported ABIs can be divided into two groups:
127 .Bl -tag -width "Dv ILP32"
132 types machine representations all have 4-byte size.
135 type machine representation uses 4 bytes,
144 symbol when compiling for an
148 Some machines support more that one
151 Typically these are 64-bit machines, where the
154 execution environment is accompanied by the
157 environment, which was historical 32-bit predecessor for 64-bit evolution.
159 .Bl -column -offset indent "Dv powerpc64" "Sy ILP32 counterpart"
160 .It Sy LP64 Ta Sy ILP32 counterpart
161 .It Dv amd64 Ta Dv i386
162 .It Dv powerpc64 Ta Dv powerpc
163 .It Dv mips64* Ta Dv mips*
164 .It Dv aarch64 Ta Dv armv6/armv7
167 will support execution of
171 binaries if the CPU implements
173 execution state, however
175 binaries aren't supported.
177 On all supported architectures:
178 .Bl -column -offset -indent "long long" "Size"
179 .It Sy Type Ta Sy Size
182 .It long Ta sizeof(void*)
187 Integers are represented in two's complement.
188 Alignment of integer and pointer types is natural, that is,
189 the address of the variable must be congruent to zero modulo the type size.
190 Most ILP32 ABIs, except
192 require only 4-byte alignment for 64-bit integers.
194 Machine-dependent type sizes:
195 .Bl -column -offset indent "Sy Architecture" "Sy void *" "Sy long double" "Sy time_t"
196 .It Sy Architecture Ta Sy void * Ta Sy long double Ta Sy time_t
197 .It aarch64 Ta 8 Ta 16 Ta 8
198 .It amd64 Ta 8 Ta 16 Ta 8
199 .It arm Ta 4 Ta 8 Ta 8
200 .It armv6 Ta 4 Ta 8 Ta 8
201 .It i386 Ta 4 Ta 12 Ta 4
202 .It mips Ta 4 Ta 8 Ta 8
203 .It mipsel Ta 4 Ta 8 Ta 8
204 .It mipselhf Ta 4 Ta 8 Ta 8
205 .It mipshf Ta 4 Ta 8 Ta 8
206 .It mipsn32 Ta 4 Ta 8 Ta 8
207 .It mips64 Ta 8 Ta 8 Ta 8
208 .It mips64el Ta 8 Ta 8 Ta 8
209 .It mips64elhf Ta 8 Ta 8 Ta 8
210 .It mips64hf Ta 8 Ta 8 Ta 8
211 .It powerpc Ta 4 Ta 8 Ta 8
212 .It powerpcspe Ta 4 Ta 8 Ta 8
213 .It powerpc64 Ta 8 Ta 8 Ta 8
214 .It riscv64 Ta 8 Ta 16 Ta 8
215 .It riscv64sf Ta 8 Ta 16 Ta 8
216 .It sparc64 Ta 8 Ta 16 Ta 8
220 is 8 bytes on all supported architectures except i386.
221 .Ss Endianness and Char Signedness
222 .Bl -column -offset indent "Sy Architecture" "Sy Endianness" "Sy char Signedness"
223 .It Sy Architecture Ta Sy Endianness Ta Sy char Signedness
224 .It aarch64 Ta little Ta unsigned
225 .It amd64 Ta little Ta signed
226 .It arm Ta little Ta unsigned
227 .It armv6 Ta little Ta unsigned
228 .It armv7 Ta little Ta unsigned
229 .It i386 Ta little Ta signed
230 .It mips Ta big Ta signed
231 .It mipsel Ta little Ta signed
232 .It mipselhf Ta little Ta signed
233 .It mipshf Ta big Ta signed
234 .It mipsn32 Ta big Ta signed
235 .It mips64 Ta big Ta signed
236 .It mips64el Ta little Ta signed
237 .It mips64elhf Ta little Ta signed
238 .It mips64hf Ta big Ta signed
239 .It powerpc Ta big Ta unsigned
240 .It powerpcspe Ta big Ta unsigned
241 .It powerpc64 Ta big Ta unsigned
242 .It riscv64 Ta little Ta signed
243 .It riscv64sf Ta little Ta signed
244 .It sparc64 Ta big Ta signed
247 .Bl -column -offset indent "Sy Architecture" "Sy Page Sizes"
248 .It Sy Architecture Ta Sy Page Sizes
249 .It aarch64 Ta 4K, 2M, 1G
250 .It amd64 Ta 4K, 2M, 1G
254 .It i386 Ta 4K, 2M (PAE), 4M
272 .Bl -column -offset indent "Sy Architecture" "Sy float, double" "Sy long double"
273 .It Sy Architecture Ta Sy float, double Ta Sy long double
274 .It aarch64 Ta hard Ta soft, quad precision
275 .It amd64 Ta hard Ta hard, 80 bit
276 .It arm Ta soft Ta soft, double precision
277 .It armv6 Ta hard(1) Ta hard, double precision
278 .It armv7 Ta hard(1) Ta hard, double precision
279 .It i386 Ta hard Ta hard, 80 bit
280 .It mips Ta soft Ta identical to double
281 .It mipsel Ta soft Ta identical to double
282 .It mipselhf Ta hard Ta identical to double
283 .It mipshf Ta hard Ta identical to double
284 .It mipsn32 Ta soft Ta identical to double
285 .It mips64 Ta soft Ta identical to double
286 .It mips64el Ta soft Ta identical to double
287 .It mips64elhf Ta hard Ta identical to double
288 .It mips64hf Ta hard Ta identical to double
289 .It powerpc Ta hard Ta hard, double precision
290 .It powerpcspe Ta hard Ta hard, double precision
291 .It powerpc64 Ta hard Ta hard, double precision
292 .It riscv64 Ta hard Ta hard, double precision
293 .It riscv64sf Ta soft Ta soft, double precision
294 .It sparc64 Ta hard Ta hard, quad precision
299 armv6 used the softfp ABI even though it supported only processors
300 with a floating point unit.
301 .Ss Default Tool Chain
302 .Fx uses a variety of tool chain components for the supported CPU
307 provided by the base system,
312 or an external toolchain compiler and linker provided by a port or package.
313 This table shows the default tool chain for each architecture.
314 .Bl -column -offset indent "Sy Architecture" "Sy Compiler" "Sy Linker"
315 .It Sy Architecture Ta Sy Compiler Ta Sy Linker
316 .It aarch64 Ta Clang Ta lld
317 .It amd64 Ta Clang Ta lld
318 .It arm Ta Clang Ta GNU ld 2.17.50
319 .It armv6 Ta Clang Ta lld
320 .It armv7 Ta Clang Ta lld
321 .It i386 Ta Clang Ta lld
322 .It mips Ta GCC 4.2.1 Ta GNU ld 2.17.50
323 .It mipsel Ta GCC 4.2.1 Ta GNU ld 2.17.50
324 .It mipselhf Ta GCC 4.2.1 Ta GNU ld 2.17.50
325 .It mipshf Ta GCC 4.2.1 Ta GNU ld 2.17.50
326 .It mipsn32 Ta GCC 4.2.1 Ta GNU ld 2.17.50
327 .It mips64 Ta GCC 4.2.1 Ta GNU ld 2.17.50
328 .It mips64el Ta GCC 4.2.1 Ta GNU ld 2.17.50
329 .It mips64elhf Ta GCC 4.2.1 Ta GNU ld 2.17.50
330 .It mips64hf Ta GCC 4.2.1 Ta GNU ld 2.17.50
331 .It powerpc Ta GCC 4.2.1 Ta GNU ld 2.17.50
332 .It powerpcspe Ta GCC 4.2.1 Ta GNU ld 2.17.50
333 .It powerpc64 Ta GCC 4.2.1 Ta GNU ld 2.17.50
334 .It riscv64 Ta GCC(1) Ta GNU ld(1)
335 .It riscv64sf Ta GCC(1) Ta GNU ld(1)
336 .It sparc64 Ta GCC 4.2.1 Ta GNU ld 2.17.50
339 (1) External toolchain provided by ports/packages.
341 Note that GCC 4.2.1 is deprecated, and scheduled for removal on 2020-03-31.
342 Any CPU architectures not migrated by then
343 (to either base system Clang or external toolchain)
344 may be removed from the tree after that date.
345 Unless the make variable
346 .Dv MAKE_OBSOLETE_GCC
347 is defined, make universe will not build mips, powerpc, nor sparc64
348 architectures unless the xtoolchain binaries have been installed for
350 .Ss MACHINE_ARCH vs MACHINE_CPUARCH
352 should be preferred in Makefiles when the generic
353 architecture is being tested.
355 should be preferred when there is something specific to a particular type of
356 architecture where there is a choice of many, or could be a choice of many.
357 .Bl -column -offset indent "Dv MACHINE" "Dv MACHINE_CPUARCH" "Dv MACHINE_ARCH"
358 .It Dv MACHINE Ta Dv MACHINE_CPUARCH Ta Dv MACHINE_ARCH
359 .It arm64 Ta aarch64 Ta aarch64
360 .It amd64 Ta amd64 Ta amd64
361 .It arm Ta arm Ta arm, armv6, armv7
362 .It i386 Ta i386 Ta i386
363 .It mips Ta mips Ta mips, mipsel, mips64, mips64el, mipshf, mipselhf, mips64elhf, mipsn32
364 .It powerpc Ta powerpc Ta powerpc, powerpcspe, powerpc64
365 .It riscv Ta riscv Ta riscv64, riscv64sf
366 .It sparc64 Ta sparc64 Ta sparc64
368 .Ss Predefined Macros
369 The compiler provides a number of predefined macros.
370 Some of these provide architecture-specific details and are explained below.
371 Other macros, including those required by the language standard, are not
374 The full set of predefined macros can be obtained with this command:
375 .Bd -literal -offset indent
376 cc -x c -dM -E /dev/null
379 Common type size and endianness macros:
380 .Bl -column -offset indent "BYTE_ORDER" "Sy Meaning"
381 .It Sy Macro Ta Sy Meaning
382 .It Dv __LP64__ Ta 64-bit (8-byte) long and pointer, 32-bit (4-byte) int
383 .It Dv __ILP32__ Ta 32-bit (4-byte) int, long and pointer
384 .It Dv BYTE_ORDER Ta Either Dv BIG_ENDIAN or Dv LITTLE_ENDIAN .
390 Architecture-specific macros:
391 .Bl -column -offset indent "Sy Architecture" "Sy Predefined macros"
392 .It Sy Architecture Ta Sy Predefined macros
393 .It aarch64 Ta Dv __aarch64__
394 .It amd64 Ta Dv __amd64__, Dv __x86_64__
395 .It arm Ta Dv __arm__
396 .It armv6 Ta Dv __arm__, Dv __ARM_ARCH >= 6
397 .It armv7 Ta Dv __arm__, Dv __ARM_ARCH >= 7
398 .It i386 Ta Dv __i386__
399 .It mips Ta Dv __mips__, Dv __MIPSEB__, Dv __mips_o32
400 .It mipsel Ta Dv __mips__, Dv __mips_o32
401 .It mipselhf Ta Dv __mips__, Dv __mips_o32
402 .It mipshf Ta Dv __mips__, Dv __MIPSEB__, Dv __mips_o32
403 .It mipsn32 Ta Dv __mips__, Dv __MIPSEB__, Dv __mips_n32
404 .It mips64 Ta Dv __mips__, Dv __MIPSEB__, Dv __mips_n64
405 .It mips64el Ta Dv __mips__, Dv __mips_n64
406 .It mips64elhf Ta Dv __mips__, Dv __mips_n64
407 .It mips64hf Ta Dv __mips__, Dv __MIPSEB__, Dv __mips_n64
408 .It powerpc Ta Dv __powerpc__
409 .It powerpcspe Ta Dv __powerpc__, Dv __SPE__
410 .It powerpc64 Ta Dv __powerpc__, Dv __powerpc64__
411 .It riscv64 Ta Dv __riscv, Dv __riscv_xlen == 64
412 .It riscv64sf Ta Dv __riscv, Dv __riscv_xlen == 64
413 .It sparc64 Ta Dv __sparc64__
416 Compilers may define additional variants of architecture-specific macros.
417 The macros above are preferred for use in
419 .Ss Important Xr make 1 variables
420 Most of the externally settable variables are defined in the
423 These variables are not otherwise documented and are used extensively
425 .Bl -column -offset indent "Sy Variable" "Sy Meaning and usage"
426 .It Dv MACHINE Represent the hardware platform.
427 This is the same as the native platform's
431 It defines both the userland / kernel interface, as well as the
432 bootloader / kernel interface.
433 It should only be used in these contexts.
434 Each CPU architecture may have multiple hardware platforms it supports
438 It is used to collect together all the files from
441 It is often the same as
443 just as one CPU architecture can be implemented by many different
444 hardware platforms, one hardware platform may support multiple CPU
445 architecture family members, though with different binaries.
448 of i386 supported the IBM-AT hardware platform while the
450 of pc98 supported the Japanese company NEC's PC-9801 and PC-9821
452 Both of these hardware platforms supported only the
454 of i386 where they shared a common ABI, except for certain kernel /
455 userland interfaces relating to underlying hardware platform
456 differences in bus architecture, device enumeration and boot interface.
459 should only be used in src/sys and src/stand or in system imagers or
461 .It Dv MACHINE_ARCH Represents the CPU processor architecture.
462 This is the same as the native platforms
466 It defines the CPU instruction family supported.
467 It may also encode a variation in the byte ordering of multi-byte
469 It may also encode a variation in the size of the integer or pointer.
470 It may also encode a ISA revision.
471 It may also encode hard versus soft floating point ABI and usage.
472 It may also encode a variant ABI when the other factors do not
473 uniquely define the ABI (e.g., MIPS' n32 ABI).
476 defines the ABI used by the system.
477 For example, the MIPS CPU processor family supports 9 different
478 combinations encoding pointer size, endian and hard versus soft float (for
479 8 combinations) as well as N32 (which only ever had one variation of
481 Generally, the plain CPU name specifies the most common (or at least
482 first) variant of the CPU.
483 This is why mips and mips64 imply 'big endian' while 'arm' and 'armv7'
485 If we ever were to support the so-called x32 ABI (using 32-bit
486 pointers on the amd64 architecture), it would most likely be encoded
488 It is unfortunate that amd64 specifies the 64-bit evolution of the x86
489 platform (it matches the 'first rule') as everybody else uses x86_64.
490 There is no standard name for the processor: each OS selects its own
492 .It Dv MACHINE_CPUARCH Represents the source location for a given
494 It is generally the common prefix for all the MACHINE_ARCH that
495 share the same implementation, though 'riscv' breaks this rule.
498 is defined to be mips for all the flavors of mips that we support
499 since we support them all with a shared set of sources.
500 While amd64 and i386 are closely related, MACHINE_CPUARCH is not x86
502 The FreeBSD source base supports amd64 and i386 with two
503 distinct source bases living in subdirectories named amd64 and i386
504 (though behind the scenes there's some sharing that fits into this
506 .It Dv CPUTYPE Sets the flavor of
509 It is used to optimize the build for a specific CPU / core that the
511 Generally, this does not change the ABI, though it can be a fine line
512 between optimization for specific cases.
513 .It Dv TARGET Used to set
515 in the top level Makefile for cross building.
516 Unused outside of that scope.
517 It is not passed down to the rest of the build.
518 Makefiles outside of the top level should not use it at all (though
519 some have their own private copy for hysterical raisons).
520 .It Dv TARGET_ARCH Used to set
522 by the top level Makefile for cross building.
524 .Dv TARGET , it is unused outside of that scope.
532 manual page appeared in