1 /* Set flags signalling availability of kernel features based on given
3 Copyright (C) 1999-2006, 2007, 2008, 2009 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
21 /* This file must not contain any C code. At least it must be protected
22 to allow using the file also in assembler files. */
24 #ifndef __LINUX_KERNEL_VERSION
25 /* We assume the worst; all kernels should be supported. */
26 # define __LINUX_KERNEL_VERSION 0
29 /* We assume for __LINUX_KERNEL_VERSION the same encoding used in
30 linux/version.h. I.e., the major, minor, and subminor all get a
31 byte with the major number being in the highest byte. This means
32 we can do numeric comparisons.
34 In the following we will define certain symbols depending on
35 whether the describes kernel feature is available in the kernel
36 version given by __LINUX_KERNEL_VERSION. We are not always exactly
37 recording the correct versions in which the features were
38 introduced. If somebody cares these values can afterwards be
39 corrected. Most of the numbers here are set corresponding to
42 /* `getcwd' system call. */
43 #if __LINUX_KERNEL_VERSION >= 131584
44 # define __ASSUME_GETCWD_SYSCALL 1
47 /* Real-time signal became usable in 2.1.70. */
48 #if __LINUX_KERNEL_VERSION >= 131398
49 # define __ASSUME_REALTIME_SIGNALS 1
52 /* When were the `pread'/`pwrite' syscalls introduced? */
53 #if __LINUX_KERNEL_VERSION >= 131584
54 # define __ASSUME_PREAD_SYSCALL 1
55 # define __ASSUME_PWRITE_SYSCALL 1
58 /* When was `poll' introduced? */
59 #if __LINUX_KERNEL_VERSION >= 131584
60 # define __ASSUME_POLL_SYSCALL 1
63 /* The `lchown' syscall was introduced in 2.1.80. */
64 #if __LINUX_KERNEL_VERSION >= 131408
65 # define __ASSUME_LCHOWN_SYSCALL 1
68 /* When did the `setresuid' sysall became available? */
69 #if __LINUX_KERNEL_VERSION >= 131584 && !defined __sparc__
70 # define __ASSUME_SETRESUID_SYSCALL 1
73 /* The SIOCGIFNAME ioctl is available starting with 2.1.50. */
74 #if __LINUX_KERNEL_VERSION >= 131408
75 # define __ASSUME_SIOCGIFNAME 1
78 /* MSG_NOSIGNAL was at least available with Linux 2.2.0. */
79 #if __LINUX_KERNEL_VERSION >= 131584
80 # define __ASSUME_MSG_NOSIGNAL 1
83 /* The sendfile syscall was introduced in 2.2.0. */
84 #if __LINUX_KERNEL_VERSION >= 131584
85 # define __ASSUME_SENDFILE 1
88 /* Only very old kernels had no real symlinks for terminal descriptors
90 #if __LINUX_KERNEL_VERSION >= 131584
91 # define __ASSUME_PROC_SELF_FD_SYMLINK 1
94 /* On x86 another `getrlimit' syscall was added in 2.3.25. */
95 #if __LINUX_KERNEL_VERSION >= 131865 && defined __i386__
96 # define __ASSUME_NEW_GETRLIMIT_SYSCALL 1
99 /* On x86 the truncate64/ftruncate64 syscalls were introduced in 2.3.31. */
100 #if __LINUX_KERNEL_VERSION >= 131871 && defined __i386__
101 # define __ASSUME_TRUNCATE64_SYSCALL 1
104 /* On x86 the mmap2 syscall was introduced in 2.3.31. */
105 #if __LINUX_KERNEL_VERSION >= 131871 && defined __i386__
106 # define __ASSUME_MMAP2_SYSCALL 1
109 /* On x86 the stat64/lstat64/fstat64 syscalls were introduced in 2.3.34. */
110 #if __LINUX_KERNEL_VERSION >= 131874 && defined __i386__
111 # define __ASSUME_STAT64_SYSCALL 1
114 /* On sparc the truncate64/ftruncate64/mmap2/stat64/lstat64/fstat64
115 syscalls were introduced in 2.3.35. */
116 #if __LINUX_KERNEL_VERSION >= 131875 \
117 && (defined __sparc__ && !defined __arch64__)
118 # define __ASSUME_TRUNCATE64_SYSCALL 1
119 # define __ASSUME_MMAP2_SYSCALL 1
120 # define __ASSUME_STAT64_SYSCALL 1
123 /* I know for sure that getrlimit are in 2.3.35 on powerpc. */
124 #if __LINUX_KERNEL_VERSION >= 131875 && defined __powerpc__
125 # define __ASSUME_NEW_GETRLIMIT_SYSCALL 1
128 /* I know for sure that these are in 2.3.35 on powerpc. But PowerPC64 does not
129 support separate 64-bit syscalls, already 64-bit */
130 #if __LINUX_KERNEL_VERSION >= 131875 && defined __powerpc__ \
131 && !defined __powerpc64__
132 # define __ASSUME_TRUNCATE64_SYSCALL 1
133 # define __ASSUME_STAT64_SYSCALL 1
136 /* Linux 2.3.39 introduced 32bit UID/GIDs. Some platforms had 32
137 bit type all along. */
138 #if __LINUX_KERNEL_VERSION >= 131879 || defined __powerpc__
139 # define __ASSUME_32BITUIDS 1
142 /* Linux 2.3.39 sparc added setresuid. */
143 #if __LINUX_KERNEL_VERSION >= 131879 && defined __sparc__
144 # define __ASSUME_SETRESUID_SYSCALL 1
147 #if __LINUX_KERNEL_VERSION >= 131879
148 # define __ASSUME_SETRESGID_SYSCALL 1
151 /* Linux 2.3.39 introduced IPC64. Except for powerpc. */
152 #if __LINUX_KERNEL_VERSION >= 131879 && !defined __powerpc__
153 # define __ASSUME_IPC64 1
156 /* We can use the LDTs for threading with Linux 2.3.99 and newer. */
157 #if __LINUX_KERNEL_VERSION >= 131939
158 # define __ASSUME_LDT_WORKS 1
161 /* Linux 2.4.0 on PPC introduced a correct IPC64. But PowerPC64 does not
162 support a separate 64-bit sys call, already 64-bit */
163 #if __LINUX_KERNEL_VERSION >= 132096 && defined __powerpc__ \
164 && !defined __powerpc64__
165 # define __ASSUME_IPC64 1
168 /* SH kernels got stat64, mmap2, and truncate64 during 2.4.0-test. */
169 #if __LINUX_KERNEL_VERSION >= 132096 && defined __sh__
170 # define __ASSUME_TRUNCATE64_SYSCALL 1
171 # define __ASSUME_MMAP2_SYSCALL 1
172 # define __ASSUME_STAT64_SYSCALL 1
175 /* The changed st_ino field appeared in 2.4.0-test6. But we cannot
176 distinguish this version from other 2.4.0 releases. Therefore play
177 save and assume it available is for 2.4.1 and up. However, SH is lame,
178 and still does not have a 64-bit inode field. */
179 #if __LINUX_KERNEL_VERSION >= 132097 && !defined __alpha__ && !defined __sh__
180 # define __ASSUME_ST_INO_64_BIT 1
183 /* To support locking of large files a new fcntl() syscall was introduced
184 in 2.4.0-test7. We test for 2.4.1 for the earliest version we know
185 the syscall is available. */
186 #if __LINUX_KERNEL_VERSION >= 132097 && (defined __i386__ || defined __sparc__)
187 # define __ASSUME_FCNTL64 1
190 /* The AT_CLKTCK auxiliary vector entry was introduction in the 2.4.0
192 #if __LINUX_KERNEL_VERSION >= 132097
193 # define __ASSUME_AT_CLKTCK 1
196 /* Arm got fcntl64 in 2.4.4, PowerPC and SH have it also in 2.4.4 (I
197 don't know when it got introduced). But PowerPC64 does not support
198 separate FCNTL64 call, FCNTL is already 64-bit */
199 #if __LINUX_KERNEL_VERSION >= 132100 \
200 && (defined __powerpc__ || defined __sh__) \
201 && !defined __powerpc64__
202 # define __ASSUME_FCNTL64 1
205 /* The getdents64 syscall was introduced in 2.4.0-test7. We test for
206 2.4.1 for the earliest version we know the syscall is available. */
207 #if __LINUX_KERNEL_VERSION >= 132097
208 # define __ASSUME_GETDENTS64_SYSCALL 1
211 /* When did O_DIRECTORY became available? Early in 2.3 but when?
212 Be safe, use 2.3.99. */
213 #if __LINUX_KERNEL_VERSION >= 131939
214 # define __ASSUME_O_DIRECTORY 1
217 /* Starting with one of the 2.4.0 pre-releases the Linux kernel passes
218 up the page size information. */
219 #if __LINUX_KERNEL_VERSION >= 132097
220 # define __ASSUME_AT_PAGESIZE 1
223 /* Starting with at least 2.4.0 the kernel passes the uid/gid unconditionally
225 #if __LINUX_KERNEL_VERSION >= 132097
226 # define __ASSUME_AT_XID 1
229 /* Starting with 2.4.5 kernels PPC passes the AUXV in the standard way
230 and the vfork syscall made it into the official kernel. */
231 #if __LINUX_KERNEL_VERSION >= (132096+5) && defined __powerpc__
232 # define __ASSUME_STD_AUXV 1
233 # define __ASSUME_VFORK_SYSCALL 1
236 /* Starting with 2.4.5 kernels the mmap2 syscall made it into the official
237 kernel. But PowerPC64 does not support a separate MMAP2 call. */
238 #if __LINUX_KERNEL_VERSION >= (132096+5) && defined __powerpc__ \
239 && !defined __powerpc64__
240 # define __ASSUME_MMAP2_SYSCALL 1
243 /* Starting with 2.4.21 PowerPC implements the new prctl syscall.
244 This allows applications to get/set the Floating Point Exception Mode. */
245 #if __LINUX_KERNEL_VERSION >= (132096+21) && defined __powerpc__
246 # define __ASSUME_NEW_PRCTL_SYSCALL 1
249 /* Starting with 2.4.21 the PowerPC32 clone syscall works as expected. */
250 #if __LINUX_KERNEL_VERSION >= (132096+21) && defined __powerpc__ \
251 && !defined __powerpc64__
252 # define __ASSUME_FIXED_CLONE_SYSCALL 1
255 /* Starting with 2.4.21 PowerPC64 implements the new rt_sigreturn syscall.
256 The new rt_sigreturn takes an ucontext pointer allowing rt_sigreturn
257 to be used in the set/swapcontext implementation. */
258 #if __LINUX_KERNEL_VERSION >= (132096+21) && defined __powerpc64__
259 # define __ASSUME_NEW_RT_SIGRETURN_SYSCALL 1
262 /* On x86, the set_thread_area syscall was introduced in 2.5.29, but its
263 semantics was changed in 2.5.30, and again after 2.5.31. */
264 #if __LINUX_KERNEL_VERSION >= 132384 && defined __i386__
265 # define __ASSUME_SET_THREAD_AREA_SYSCALL 1
268 /* The vfork syscall on x86 and arm was definitely available in 2.4. */
269 #if __LINUX_KERNEL_VERSION >= 132097 && defined __i386__
270 # define __ASSUME_VFORK_SYSCALL 1
273 /* Alpha switched to a 64-bit timeval sometime before 2.2.0. */
274 #if __LINUX_KERNEL_VERSION >= 131584 && defined __alpha__
275 # define __ASSUME_TIMEVAL64 1
278 /* The late 2.5 kernels saw a lot of new CLONE_* flags. Summarize
279 their availability with one define. The changes were made first
280 for i386 and the have to be done separately for the other archs.
281 For i386 we pick 2.5.50 as the first version with support.
282 For ia64, s390*, PPC, x86-64, and SH we pick 2.5.64 as the first
283 version with support. */
284 #if ((__LINUX_KERNEL_VERSION >= 132402 && defined __i386__) \
285 || (__LINUX_KERNEL_VERSION >= 132416 \
286 && (defined __ia64__ || defined __s390__ \
287 || defined __powerpc__ || defined __x86_64__ || defined __sh__)))
288 # define __ASSUME_CLONE_THREAD_FLAGS 1
291 /* Beginning with 2.5.63 support for realtime and monotonic clocks and
292 timers based on them is available. */
293 #if __LINUX_KERNEL_VERSION >= 132415
294 # define __ASSUME_POSIX_TIMERS 1
297 /* Beginning with 2.6.12 the clock and timer supports CPU clocks. */
298 #if __LINUX_KERNEL_VERSION >= 0x2060c
299 # define __ASSUME_POSIX_CPU_TIMERS 1
302 /* With kernel 2.4.17 we always have netlink support. */
303 #if __LINUX_KERNEL_VERSION >= (132096+17)
304 # define __ASSUME_NETLINK_SUPPORT 1
307 /* The requeue futex functionality was introduced in 2.5.70. */
308 #if __LINUX_KERNEL_VERSION >= 132422
309 # define __ASSUME_FUTEX_REQUEUE 1
312 /* The statfs64 syscalls are available in 2.5.74. */
313 #if __LINUX_KERNEL_VERSION >= 132426
314 # define __ASSUME_STATFS64 1
317 /* Starting with at least 2.5.74 the kernel passes the setuid-like exec
318 flag unconditionally up to the child. */
319 #if __LINUX_KERNEL_VERSION >= 132426
320 # define __ASSUME_AT_SECURE 1
323 /* Starting with the 2.5.75 kernel the kernel fills in the correct value
324 in the si_pid field passed as part of the siginfo_t struct to signal
326 #if __LINUX_KERNEL_VERSION >= 132427
327 # define __ASSUME_CORRECT_SI_PID 1
330 /* The tgkill syscall was instroduced for i386 in 2.5.75. For Alpha
331 it was introduced in 2.6.0-test1 which unfortunately cannot be
332 distinguished from 2.6.0. On x86-64, ppc, and ppc64 it was
333 introduced in 2.6.0-test3. */
334 #if (__LINUX_KERNEL_VERSION >= 132427 && defined __i386__) \
335 || (__LINUX_KERNEL_VERSION >= 132609 && defined __alpha__) \
336 || (__LINUX_KERNEL_VERSION >= 132609 && defined __x86_64__) \
337 || (__LINUX_KERNEL_VERSION >= 132609 && defined __powerpc__) \
338 || (__LINUX_KERNEL_VERSION >= 132609 && defined __sh__)
339 # define __ASSUME_TGKILL 1
342 /* The utimes syscall has been available for some architectures
343 forever. For x86 it was introduced after 2.5.75, for x86-64,
344 ppc, and ppc64 it was introduced in 2.6.0-test3. */
345 #if defined __alpha__ || defined __ia64__ \
346 || defined __sparc__ \
347 || (__LINUX_KERNEL_VERSION > 132427 && defined __i386__) \
348 || (__LINUX_KERNEL_VERSION > 132609 && defined __x86_64__) \
349 || (__LINUX_KERNEL_VERSION >= 132609 && defined __powerpc__) \
350 || (__LINUX_KERNEL_VERSION >= 132609 && defined __sh__)
351 # define __ASSUME_UTIMES 1
354 // XXX Disabled for now since the semantics we want is not achieved.
356 /* The CLONE_STOPPED flag was introduced in the 2.6.0-test1 series. */
357 #if __LINUX_KERNEL_VERSION >= 132609
358 # define __ASSUME_CLONE_STOPPED 1
362 /* The fixed version of the posix_fadvise64 syscall appeared in
363 2.6.0-test3. At least for x86. Powerpc support appeared in
364 2.6.2, but for 32-bit userspace only. */
365 #if (__LINUX_KERNEL_VERSION >= 132609 && defined __i386__) \
366 || (__LINUX_KERNEL_VERSION >= 132610 && defined __powerpc__ \
367 && !defined __powerpc64__)
368 # define __ASSUME_FADVISE64_64_SYSCALL 1
371 /* The PROT_GROWSDOWN/PROT_GROWSUP flags were introduced in the 2.6.0-test
373 #if __LINUX_KERNEL_VERSION >= 132609
374 # define __ASSUME_PROT_GROWSUPDOWN 1
377 /* Starting with 2.6.0 PowerPC adds signal/swapcontext support for Vector
378 SIMD (AKA Altivec, VMX) instructions and register state. This changes
379 the overall size of the sigcontext and adds the swapcontext syscall. */
380 #if __LINUX_KERNEL_VERSION >= 132608 && defined __powerpc__
381 # define __ASSUME_SWAPCONTEXT_SYSCALL 1
384 /* The CLONE_DETACHED flag is not necessary in 2.6.2 kernels, it is
386 #if __LINUX_KERNEL_VERSION >= 132610
387 # define __ASSUME_NO_CLONE_DETACHED 1
390 /* Starting with version 2.6.4-rc1 the getdents syscall returns d_type
391 information as well and in between 2.6.5 and 2.6.8 most compat wrappers
392 were fixed too. Except s390{,x} which was fixed in 2.6.11. */
393 #if (__LINUX_KERNEL_VERSION >= 0x020608 && !defined __s390__) \
394 || (__LINUX_KERNEL_VERSION >= 0x02060b && defined __s390__)
395 # define __ASSUME_GETDENTS32_D_TYPE 1
398 /* Starting with version 2.5.3, the initial location returned by `brk'
399 after exec is always rounded up to the next page. */
400 #if __LINUX_KERNEL_VERSION >= 132355
401 # define __ASSUME_BRK_PAGE_ROUNDED 1
404 /* Starting with version 2.6.9, the waitid system call is available.
405 Except for powerpc{,64} and s390{,x}, where it is available in 2.6.12. */
406 #if (__LINUX_KERNEL_VERSION >= 0x020609 \
407 && !defined __powerpc__ && !defined __s390__) \
408 || (__LINUX_KERNEL_VERSION >= 0x02060c \
409 && (defined __powerpc__ || defined __s390__))
410 # define __ASSUME_WAITID_SYSCALL 1
413 /* Starting with version 2.6.9, SSI_IEEE_RAISE_EXCEPTION exists. */
414 #if __LINUX_KERNEL_VERSION >= 0x020609 && defined __alpha__
415 #define __ASSUME_IEEE_RAISE_EXCEPTION 1
418 /* On sparc64 stat64/lstat64/fstat64 syscalls were introduced in 2.6.12. */
419 #if __LINUX_KERNEL_VERSION >= 0x02060c && defined __sparc__ \
420 && defined __arch64__
421 # define __ASSUME_STAT64_SYSCALL 1
424 /* Early kernel used "shm" as the filesystem name for the filesystem used
425 for shm_open etc. Later it is "tmpfs". 2.4.20 is a safe bet for the
427 #if __LINUX_KERNEL_VERSION >= 0x02041a
428 # define __ASSUME_TMPFS_NAME 1
431 /* pselect/ppoll were introduced just after 2.6.16-rc1. Due to the way
432 the kernel versions are advertised we can only rely on 2.6.17 to have
433 the code. On x86_64 and SH this appeared first in 2.6.19-rc1,
434 on ia64 in 2.6.22-rc1 and on alpha just after 2.6.22-rc1. */
435 #if __LINUX_KERNEL_VERSION >= 0x020611 \
436 && ((!defined __x86_64__ && !defined __sh__ && !defined __ia64__ \
437 && !defined __alpha__) \
438 || (__LINUX_KERNEL_VERSION >= 0x020613 \
439 && (defined __x86_64__ || defined __sh__)) \
440 || (__LINUX_KERNEL_VERSION >= 0x020616 && defined __ia64__) \
441 || (__LINUX_KERNEL_VERSION >= 0x020617 && defined __alpha__))
442 # define __ASSUME_PSELECT 1
443 # define __ASSUME_PPOLL 1
446 /* The *at syscalls were introduced just after 2.6.16-rc1. Due to the way the
447 kernel versions are advertised we can only rely on 2.6.17 to have
448 the code. On PPC they were introduced in 2.6.17-rc1, on SH in 2.6.19-rc1
449 and on Alpha just after 2.6.22-rc1. */
450 #if __LINUX_KERNEL_VERSION >= 0x020611 \
451 && ((!defined __sh__ && !defined __alpha__) \
452 || (__LINUX_KERNEL_VERSION >= 0x020613 && defined __sh__) \
453 || (__LINUX_KERNEL_VERSION >= 0x020617 && defined __alpha__))
454 # define __ASSUME_ATFCTS 1
457 /* Support for inter-process robust mutexes was added in 2.6.17. */
458 #if __LINUX_KERNEL_VERSION >= 0x020611 \
459 && ((!defined __sh__ && !defined __alpha__) \
460 || (__LINUX_KERNEL_VERSION >= 0x020613 && defined __sh__) \
461 || (__LINUX_KERNEL_VERSION >= 0x020617 && defined __alpha__))
462 # define __ASSUME_SET_ROBUST_LIST 1
465 /* Pessimistically assume that 2.6.18 introduced real handling of
466 large numbers of requests to readv and writev and that we don't
467 need a fallback. It likely worked for much longer. */
468 #if __LINUX_KERNEL_VERSION >= 0x020612
469 # define __ASSUME_COMPLETE_READV_WRITEV 1
472 /* Support for PI futexes was added in 2.6.18. */
473 #if __LINUX_KERNEL_VERSION >= 0x020612
474 # define __ASSUME_FUTEX_LOCK_PI 1
477 /* Support for utimensat syscall was added in 2.6.22, on alpha and s390
478 only after 2.6.22-rc1. */
479 #if __LINUX_KERNEL_VERSION >= 0x020616 \
480 && ((!defined __sh__ && !defined __alpha__) \
481 || __LINUX_KERNEL_VERSION >= 0x020617)
482 # define __ASSUME_UTIMENSAT 1
485 /* Support for private futexes was added in 2.6.22. */
486 #if __LINUX_KERNEL_VERSION >= 0x020616
487 # define __ASSUME_PRIVATE_FUTEX 1
490 /* Support for fallocate was added in 2.6.23, on s390
491 only after 2.6.23-rc1. */
492 #if __LINUX_KERNEL_VERSION >= 0x020617 \
493 && ((!defined __s390__ && !defined __alpha__) \
494 || (__LINUX_KERNEL_VERSION >= 0x020618 && defined __s390__))
495 # define __ASSUME_FALLOCATE 1
498 /* Support for various CLOEXEC and NONBLOCK flags was added for x86,
499 x86-64, PPC, IA-64, SPARC< and S390 in 2.6.23. */
500 #if __LINUX_KERNEL_VERSION >= 0x020617 \
501 && (defined __i386__ || defined __x86_64__ || defined __powerpc__ \
502 || defined __ia64__ || defined __sparc__ || defined __s390__)
503 # define __ASSUME_O_CLOEXEC 1
506 /* Support for ADJ_OFFSET_SS_READ was added in 2.6.24. */
507 #if __LINUX_KERNEL_VERSION >= 0x020618
508 # define __ASSUME_ADJ_OFFSET_SS_READ 1
511 /* Support for various CLOEXEC and NONBLOCK flags was added for x86,
512 x86-64, PPC, IA-64, and SPARC in 2.6.27. */
513 #if __LINUX_KERNEL_VERSION >= 0x02061b \
514 && (defined __i386__ || defined __x86_64__ || defined __powerpc__ \
515 || defined __ia64__ || defined __sparc__ || defined __s390__)
516 # define __ASSUME_SOCK_CLOEXEC 1
517 # define __ASSUME_IN_NONBLOCK 1
518 # define __ASSUME_PIPE2 1
519 # define __ASSUME_EVENTFD2 1
520 # define __ASSUME_SIGNALFD4 1
523 /* Support for the accept4 syscall was added in 2.6.28. */
524 #if __LINUX_KERNEL_VERSION >= 0x02061c \
525 && (defined __i386__ || defined __x86_64__ || defined __powerpc__ \
526 || defined __sparc__ || defined __s390__)
527 # define __ASSUME_ACCEPT4 1
530 /* Support for the FUTEX_CLOCK_REALTIME flag was added in 2.6.29. */
531 #if __LINUX_KERNEL_VERSION >= 0x02061d
532 # define __ASSUME_FUTEX_CLOCK_REALTIME 1
535 /* Support for the AT_RANDOM auxiliary vector entry was added in 2.6.29. */
536 #if __LINUX_KERNEL_VERSION >= 0x02061d
537 # define __ASSUME_AT_RANDOM 1
540 /* Support for preadv and pwritev was added in 2.6.30. */
541 #if __LINUX_KERNEL_VERSION >= 0x02061e
542 # define __ASSUME_PREADV 1
543 # define __ASSUME_PWRITEV 1