man2/syscalls.2

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   2 .\" with some input from Stepan Kasal <kasal@ucw.cz>
   3 .\"
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  30 .\"
  31 .TH SYSCALLS 2 2018-02-02 "Linux" "Linux Programmer's Manual"
  32 .SH NAME
  33 syscalls \- Linux system calls
  34 .SH SYNOPSIS
  35 Linux system calls.
  36 .SH DESCRIPTION
  37 The system call is the fundamental interface between an application
  38 and the Linux kernel.
  39 .SS System calls and library wrapper functions
  40 System calls are generally not invoked directly,
  41 but rather via wrapper functions in glibc (or perhaps some other library).
  42 For details of direct invocation of a system call, see
  43 .BR intro (2).
  44 Often, but not always, the name of the wrapper function is the same
  45 as the name of the system call that it invokes.
  46 For example, glibc contains a function
  47 .BR chdir ()
  48 which invokes the underlying "chdir" system call.
  49 .PP
  50 Often the glibc wrapper function is quite thin, doing little work
  51 other than copying arguments to the right registers
  52 before invoking the system call,
  53 and then setting
  54 .I errno
  55 appropriately after the system call has returned.
  56 (These are the same steps that are performed by
  57 .BR syscall (2),
  58 which can be used to invoke system calls
  59 for which no wrapper function is provided.)
  60 Note: system calls indicate a failure by returning a negative error
  61 number to the caller on architectures without a separate error register/flag,
  62 as noted in
  63 .BR syscall (2);
  64 when this happens,
  65 the wrapper function negates the returned error number
  66 (to make it positive), copies it to
  67 .IR errno ,
  68 and returns \-1 to the caller of the wrapper.
  69 .PP
  70 Sometimes, however, the wrapper function does some extra work
  71 before invoking the system call.
  72 For example, nowadays there are (for reasons described below) two
  73 related system calls,
  74 .BR truncate (2)
  75 and
  76 .BR truncate64 (2),
  77 and the glibc
  78 .BR truncate ()
  79 wrapper function checks which of those system calls
  80 are provided by the kernel and determines which should be employed.
  81 .SS System call list
  82 Below is a list of the Linux system calls.
  83 In the list, the
  84 .I Kernel
  85 column indicates the kernel version
  86 for those system calls that were new in Linux 2.2,
  87 or have appeared since that kernel version.
  88 Note the following points:
  89 .IP * 3
  90 Where no kernel version is indicated,
  91 the system call appeared in kernel 1.0 or earlier.
  92 .IP *
  93 Where a system call is marked "1.2"
  94 this means the system call probably appeared in a 1.1.x kernel version,
  95 and first appeared in a stable kernel with 1.2.
  96 (Development of the 1.2 kernel was initiated from a branch of kernel
  97 1.0.6 via the 1.1.x unstable kernel series.)
  98 .IP *
  99 Where a system call is marked "2.0"
 100 this means the system call probably appeared in a 1.3.x kernel version,
 101 and first appeared in a stable kernel with 2.0.
 102 (Development of the 2.0 kernel was initiated from a branch of kernel
 103 1.2.x, somewhere around 1.2.10,
 104 via the 1.3.x unstable kernel series.)
 105 .\" Was kernel 2.0 started from a branch of 1.2.10?
 106 .\" At least from the timestamps of the tarballs of
 107 .\" of 1.2.10 and 1.3.0, that's how it looks, but in
 108 .\" fact the diff doesn't seem very clear, the
 109 .\" 1.3.0 .tar.bz is much bigger (2.0 MB) than the
 110 .\" 1.2.10 .tar.bz2 (1.8 MB), and AEB points out the
 111 .\" timestamps of some files in 1.3.0 seem to be older
 112 .\" than those in 1.2.10.  All of this suggests
 113 .\" that there might not have been a clean branch point.
 114 .IP *
 115 Where a system call is marked "2.2"
 116 this means the system call probably appeared in a 2.1.x kernel version,
 117 and first appeared in a stable kernel with 2.2.0.
 118 (Development of the 2.2 kernel was initiated from a branch of kernel
 119 2.0.21 via the 2.1.x unstable kernel series.)
 120 .IP *
 121 Where a system call is marked "2.4"
 122 this means the system call probably appeared in a 2.3.x kernel version,
 123 and first appeared in a stable kernel with 2.4.0.
 124 (Development of the 2.4 kernel was initiated from a branch of
 125 kernel 2.2.8 via the 2.3.x unstable kernel series.)
 126 .IP *
 127 Where a system call is marked "2.6"
 128 this means the system call probably appeared in a 2.5.x kernel version,
 129 and first appeared in a stable kernel with 2.6.0.
 130 (Development of kernel 2.6 was initiated from a branch
 131 of kernel 2.4.15 via the 2.5.x unstable kernel series.)
 132 .IP *
 133 Starting with kernel 2.6.0, the development model changed,
 134 and new system calls may appear in each 2.6.x release.
 135 In this case, the exact version number where the system call appeared
 136 is shown.
 137 This convention continues with the 3.x kernel series,
 138 which followed on from kernel 2.6.39, and the 4.x kernel series,
 139 which followed on from kernel 3.19.
 140 .IP *
 141 In some cases, a system call was added to a stable kernel
 142 series after it branched from the previous stable kernel
 143 series, and then backported into the earlier stable kernel series.
 144 For example some system calls that appeared in 2.6.x were also backported
 145 into a 2.4.x release after 2.4.15.
 146 When this is so, the version where the system call appeared
 147 in both of the major kernel series is listed.
 148 .PP
 149 The list of system calls that are available as at kernel 4.19
 150 (or in a few cases only on older kernels) is as follows:
 151 .\"
 152 .\" Looking at scripts/checksyscalls.sh in the kernel source is
 153 .\" instructive about x86 specifics.
 154 .\"
 155 .ad l
 156 .TS
 157 l2 le l
 158 ---
 159 l l l.
 160 \fBSystem call\fP       \fBKernel\fP    \fBNotes\fP
 161
 162 \fB_llseek\fP(2)        1.2
 163 \fB_newselect\fP(2)     2.0
 164 \fB_sysctl\fP(2)        2.0
 165 \fBaccept\fP(2) 2.0     See notes on \fBsocketcall\fP(2)
 166 \fBaccept4\fP(2)        2.6.28
 167 \fBaccess\fP(2) 1.0
 168 \fBacct\fP(2)   1.0
 169 \fBadd_key\fP(2)        2.6.10
 170 \fBadjtimex\fP(2)       1.0
 171 \fBalarm\fP(2)  1.0
 172 \fBalloc_hugepages\fP(2)        2.5.36  Removed in 2.5.44
 173 .\" 4adeefe161a74369e44cc8e663f240ece0470dc3
 174 \fBarc_gettls\fP(2)     3.9     ARC only
 175 \fBarc_settls\fP(2)     3.9     ARC only
 176 .\" 91e040a79df73d371f70792f30380d4e44805250
 177 \fBarc_usr_cmpxchg\fP(2)        4.9     ARC onlt
 178 .\" x86: 79170fda313ed5be2394f87aa2a00d597f8ed4a1
 179 \fBarch_prctl\fP(2)     2.6     x86_64, x86 since 4.12
 180 .\" 9674cdc74d63f346870943ef966a034f8c71ee57
 181 \fBatomic_barrier\fP(2) 2.6.34  m68k only
 182 \fBatomic_cmpxchg_32\fP(2)      2.6.34  m68k only
 183 \fBbdflush\fP(2)        1.2     T{
 184 Deprecated (does nothing)
 185 .br
 186 since 2.6
 187 T}
 188 \fBbfin_spinlock\fP(2)  2.6.22  T{
 189 Blackfin only (port removed
 190 .br
 191 in Linux 4.17)
 192 T}
 193 \fBbind\fP(2)   2.0     See notes on \fBsocketcall\fP(2)
 194 \fBbpf\fP(2)    3.18
 195 \fBbrk\fP(2)    1.0
 196 \fBbreakpoint\fP(2)     2.2     T{
 197 ARM OABI only, defined with
 198 .br
 199 \fB__ARM_NR\fP prefix
 200 T}
 201 \fBcacheflush\fP(2)     1.2     Not on x86
 202 \fBcapget\fP(2) 2.2
 203 \fBcapset\fP(2) 2.2
 204 \fBchdir\fP(2)  1.0
 205 \fBchmod\fP(2)  1.0
 206 \fBchown\fP(2)  2.2     T{
 207 See \fBchown\fP(2) for
 208 .br
 209 version details
 210 T}
 211 \fBchown32\fP(2)        2.4
 212 \fBchroot\fP(2) 1.0
 213 \fBclock_adjtime\fP(2)  2.6.39
 214 \fBclock_getres\fP(2)   2.6
 215 \fBclock_gettime\fP(2)  2.6
 216 \fBclock_nanosleep\fP(2)        2.6
 217 \fBclock_settime\fP(2)  2.6
 218 \fBclone2\fP(2) 2.4     IA-64 only
 219 \fBclone\fP(2)  1.0
 220 \fBclose\fP(2)  1.0
 221 .\" .\" dcef1f634657dabe7905af3ccda12cf7f0b6fcc1
 222 .\" .\" cc20d42986d5807cbe4f5c7c8e3dab2e59ea0db3
 223 .\" .\" db695c0509d6ec9046ee5e4c520a19fa17d9fce2
 224 .\" \fBcmpxchg\fP(2)    2.6.12  T{
 225 .\" ARM, syscall constant never was
 226 .\" .br
 227 .\" exposed to userspace, in-kernel
 228 .\" .br
 229 .\" definition had \fB__ARM_NR\fP prefix,
 230 .\" .br
 231 .\" removed in 4.4
 232 .\" T}
 233 .\" 867e359b97c970a60626d5d76bbe2a8fadbf38fb
 234 .\" bb9d812643d8a121df7d614a2b9c60193a92deb0
 235 \fBcmpxchg_badaddr\fP(2)        2.6.36  T{
 236 Tile only (port removed
 237 .br
 238 in Linux 4.17)
 239 T}
 240 \fBconnect\fP(2)        2.0     See notes on \fBsocketcall\fP(2)
 241 \fBcopy_file_range\fP(2)        4.5
 242 \fBcreat\fP(2)  1.0
 243 \fBcreate_module\fP(2)  1.0     Removed in 2.6
 244 \fBdelete_module\fP(2)  1.0
 245 .\" 1394f03221790a988afc3e4b3cb79f2e477246a9
 246 .\" 4ba66a9760722ccbb691b8f7116cad2f791cca7b
 247 \fBdma_memcpy\fP(2)     2.6.22  T{
 248 Blackfin only (port removed
 249 .br
 250 in Linux 4.17)
 251 T}
 252 \fBdup\fP(2)    1.0
 253 \fBdup2\fP(2)   1.0
 254 \fBdup3\fP(2)   2.6.27
 255 \fBepoll_create\fP(2)   2.6
 256 \fBepoll_create1\fP(2)  2.6.27
 257 \fBepoll_ctl\fP(2)      2.6
 258 \fBepoll_pwait\fP(2)    2.6.19
 259 \fBepoll_wait\fP(2)     2.6
 260 \fBeventfd\fP(2)        2.6.22
 261 \fBeventfd2\fP(2)       2.6.27
 262 \fBexecv\fP(2)  2.0     T{
 263 SPARC/SPARC64 only, for
 264 .br
 265 compatability with SunOS
 266 T}
 267 \fBexecve\fP(2) 1.0
 268 \fBexecveat\fP(2)       3.19
 269 \fBexit\fP(2)   1.0
 270 \fBexit_group\fP(2)     2.6
 271 \fBfaccessat\fP(2)      2.6.16
 272 \fBfadvise64\fP(2)      2.6
 273 .\" Implements \fBposix_fadvise\fP(2)
 274 \fBfadvise64_64\fP(2)   2.6
 275 \fBfallocate\fP(2)      2.6.23
 276 \fBfanotify_init\fP(2)  2.6.37
 277 \fBfanotify_mark\fP(2)  2.6.37
 278 .\" The fanotify calls were added in Linux 2.6.36,
 279 .\" but disabled while the API was finalized.
 280 \fBfchdir\fP(2) 1.0
 281 \fBfchmod\fP(2) 1.0
 282 \fBfchmodat\fP(2)       2.6.16
 283 \fBfchown\fP(2) 1.0
 284 \fBfchown32\fP(2)       2.4
 285 \fBfchownat\fP(2)       2.6.16
 286 \fBfcntl\fP(2)  1.0
 287 \fBfcntl64\fP(2)        2.4
 288 \fBfdatasync\fP(2)      2.0
 289 \fBfgetxattr\fP(2)      2.6; 2.4.18
 290 \fBfinit_module\fP(2)   3.8
 291 \fBflistxattr\fP(2)     2.6; 2.4.18
 292 \fBflock\fP(2)  2.0
 293 \fBfork\fP(2)   1.0
 294 \fBfree_hugepages\fP(2) 2.5.36  Removed in 2.5.44
 295 \fBfremovexattr\fP(2)   2.6; 2.4.18
 296 \fBfsetxattr\fP(2)      2.6; 2.4.18
 297 \fBfstat\fP(2)  1.0
 298 \fBfstat64\fP(2)        2.4
 299 \fBfstatat64\fP(2)      2.6.16
 300 \fBfstatfs\fP(2)        1.0
 301 \fBfstatfs64\fP(2)      2.6
 302 \fBfsync\fP(2)  1.0
 303 \fBftruncate\fP(2)      1.0
 304 \fBftruncate64\fP(2)    2.4
 305 \fBfutex\fP(2)  2.6
 306 \fBfutimesat\fP(2)      2.6.16
 307 \fBget_kernel_syms\fP(2)        1.0     Removed in 2.6
 308 \fBget_mempolicy\fP(2)  2.6.6
 309 \fBget_robust_list\fP(2)        2.6.17
 310 \fBget_thread_area\fP(2)        2.6
 311 .\" 8fcd6c45f5a65621ec809b7866a3623e9a01d4ed
 312 \fBget_tls\fP(2)        4.15    T{
 313 ARM OABI only, has
 314 .br
 315 \fB__ARM_NR\fP prefix
 316 T}
 317 \fBgetcpu\fP(2) 2.6.19
 318 \fBgetcwd\fP(2) 2.2
 319 \fBgetdents\fP(2)       2.0
 320 \fBgetdents64\fP(2)     2.4
 321 .\" parisc: 863722e856e64dae0e252b6bb546737c6c5626ce
 322 \fBgetdomainname\fP(2)  2.2     T{
 323 SPARC, SPARC64; available
 324 .br
 325 as \fBosf_getdomainname\fP(2)
 326 .br
 327 on Alpha since Linux 2.0
 328 T}
 329 .\" ec98c6b9b47df6df1c1fa6cf3d427414f8c2cf16
 330 \fBgetdtablesize\fP(2)  2.0     T{
 331 SPARC (removed in 2.6.26),
 332 .br
 333 available since Linux 2.0 on Alpha as
 334 \fBosf_getdtablesize\fP(2)
 335 T}
 336 \fBgetegid\fP(2)        1.0
 337 \fBgetegid32\fP(2)      2.4
 338 \fBgeteuid\fP(2)        1.0
 339 \fBgeteuid32\fP(2)      2.4
 340 \fBgetgid\fP(2) 1.0
 341 \fBgetgid32\fP(2)       2.4
 342 \fBgetgroups\fP(2)      1.0
 343 \fBgetgroups32\fP(2)    2.4
 344 .\" SPARC removal: ec98c6b9b47df6df1c1fa6cf3d427414f8c2cf16
 345 \fBgethostname\fP(2)    2.0     T{
 346 Alpha, was available on
 347 .br
 348 SPARC up to Linux 2.6.26
 349 T}
 350 \fBgetitimer\fP(2)      1.0
 351 \fBgetpeername\fP(2)    2.0     See notes on \fBsocketcall\fP(2)
 352 \fBgetpagesize\fP(2)    2.0     Not on x86
 353 \fBgetpgid\fP(2)        1.0
 354 \fBgetpgrp\fP(2)        1.0
 355 \fBgetpid\fP(2) 1.0
 356 \fBgetppid\fP(2)        1.0
 357 \fBgetpriority\fP(2)    1.0
 358 \fBgetrandom\fP(2)      3.17
 359 \fBgetresgid\fP(2)      2.2
 360 \fBgetresgid32\fP(2)    2.4
 361 \fBgetresuid\fP(2)      2.2
 362 \fBgetresuid32\fP(2)    2.4
 363 \fBgetrlimit\fP(2)      1.0
 364 \fBgetrusage\fP(2)      1.0
 365 \fBgetsid\fP(2) 2.0
 366 \fBgetsockname\fP(2)    2.0     See notes on \fBsocketcall\fP(2)
 367 \fBgetsockopt\fP(2)     2.0     See notes on \fBsocketcall\fP(2)
 368 \fBgettid\fP(2) 2.4.11
 369 \fBgettimeofday\fP(2)   1.0
 370 \fBgetuid\fP(2) 1.0
 371 \fBgetuid32\fP(2)       2.4
 372 \fBgetunwind\fP(2)      2.4.8   IA-64 only; deprecated
 373 \fBgetxattr\fP(2)       2.6; 2.4.18
 374 \fBgetxgid\fP(2)        2.0     Alpha only; see NOTES
 375 \fBgetxpid\fP(2)        2.0     Alpha only; see NOTES
 376 \fBgetxuid\fP(2)        2.0     Alpha only; see NOTES
 377 \fBinit_module\fP(2)    1.0
 378 \fBinotify_add_watch\fP(2)      2.6.13
 379 \fBinotify_init\fP(2)   2.6.13
 380 \fBinotify_init1\fP(2)  2.6.27
 381 \fBinotify_rm_watch\fP(2)       2.6.13
 382 \fBio_cancel\fP(2)      2.6
 383 \fBio_destroy\fP(2)     2.6
 384 \fBio_getevents\fP(2)   2.6
 385 \fBio_pgetevents\fP(2)  4.18
 386 \fBio_setup\fP(2)       2.6
 387 \fBio_submit\fP(2)      2.6
 388 \fBioctl\fP(2)  1.0
 389 \fBioperm\fP(2) 1.0
 390 \fBiopl\fP(2)   1.0
 391 \fBioprio_get\fP(2)     2.6.13
 392 \fBioprio_set\fP(2)     2.6.13
 393 \fBipc\fP(2)    1.0
 394 .\" Implements System V IPC calls
 395 \fBkcmp\fP(2)   3.5
 396 \fBkern_features\fP(2)  3.7     SPARC64 only
 397 .\" FIXME . document kern_features():
 398 .\" commit 517ffce4e1a03aea979fe3a18a3dd1761a24fafb
 399 \fBkexec_file_load\fP(2)        3.17
 400 \fBkexec_load\fP(2)     2.6.13
 401 .\" The entry in the syscall table was reserved starting in 2.6.7
 402 .\" Was named sys_kexec_load() from 2.6.7 to 2.6.16
 403 \fBkeyctl\fP(2) 2.6.10
 404 \fBkill\fP(2)   1.0
 405 \fBlchown\fP(2) 1.0     T{
 406 See \fBchown\fP(2) for
 407 .br
 408 version details
 409 T}
 410 \fBlchown32\fP(2)       2.4
 411 \fBlgetxattr\fP(2)      2.6; 2.4.18
 412 \fBlink\fP(2)   1.0
 413 \fBlinkat\fP(2) 2.6.16
 414 \fBlisten\fP(2) 2.0     See notes on \fBsocketcall\fP(2)
 415 \fBlistxattr\fP(2)      2.6; 2.4.18
 416 \fBllistxattr\fP(2)     2.6; 2.4.18
 417 \fBlookup_dcookie\fP(2) 2.6
 418 \fBlremovexattr\fP(2)   2.6; 2.4.18
 419 \fBlseek\fP(2)  1.0
 420 \fBlsetxattr\fP(2)      2.6; 2.4.18
 421 \fBlstat\fP(2)  1.0
 422 \fBlstat64\fP(2)        2.4
 423 \fBmadvise\fP(2)        2.4
 424 \fBmbind\fP(2)  2.6.6
 425 \fBmemory_ordering\fP(2)        2.2     SPARC64 only
 426 .\" 26025bbfbba33a9425be1b89eccb4664ea4c17b6
 427 .\" bb6fb6dfcc17cddac11ac295861f7608194447a7
 428 \fBmetag_get_tls\fP(2)  3.9     T{
 429 Metag only (port removed
 430 .br
 431 in Linux 4.17)
 432 T}
 433 \fBmetag_set_fpu_flags\fP(2)    3.9     T{
 434 Metag only (port removed
 435 .br
 436 in Linux 4.17)
 437 T}
 438 \fBmetag_set_tls\fP(2)  3.9     T{
 439 Metag only (port removed
 440 .br
 441 in Linux 4.17)
 442 T}
 443 \fBmetag_setglobalbit\fP(2)     3.9     T{
 444 Metag only (port removed
 445 .br
 446 in Linux 4.17)
 447 T}
 448 \fBmembarrier\fP(2)     3.17
 449 \fBmemfd_create\fP(2)   3.17
 450 \fBmigrate_pages\fP(2)  2.6.16
 451 \fBmincore\fP(2)        2.4
 452 \fBmkdir\fP(2)  1.0
 453 \fBmkdirat\fP(2)        2.6.16
 454 \fBmknod\fP(2)  1.0
 455 \fBmknodat\fP(2)        2.6.16
 456 \fBmlock\fP(2)  2.0
 457 \fBmlock2\fP(2) 4.4
 458 \fBmlockall\fP(2)       2.0
 459 \fBmmap\fP(2)   1.0
 460 \fBmmap2\fP(2)  2.4
 461 \fBmodify_ldt\fP(2)     1.0
 462 \fBmount\fP(2)  1.0
 463 \fBmove_pages\fP(2)     2.6.18
 464 \fBmprotect\fP(2)       1.0
 465 \fBmq_getsetattr\fP(2)  2.6.6
 466 .\" Implements \fBmq_getattr\fP(3) and \fBmq_setattr\fP(3)
 467 \fBmq_notify\fP(2)      2.6.6
 468 \fBmq_open\fP(2)        2.6.6
 469 \fBmq_timedreceive\fP(2)        2.6.6
 470 \fBmq_timedsend\fP(2)   2.6.6
 471 \fBmq_unlink\fP(2)      2.6.6
 472 \fBmremap\fP(2) 2.0
 473 \fBmsgctl\fP(2) 2.0     See notes on \fBipc\fP(2)
 474 \fBmsgget\fP(2) 2.0     See notes on \fBipc\fP(2)
 475 \fBmsgrcv\fP(2) 2.0     See notes on \fBipc\fP(2)
 476 \fBmsgsnd\fP(2) 2.0     See notes on \fBipc\fP(2)
 477 \fBmsync\fP(2)  2.0
 478 .\" \fBmultiplexer\fP(2)        ??      __NR_multiplexer reserved on
 479 .\"             PowerPC, but unimplemented?
 480 \fBmunlock\fP(2)        2.0
 481 \fBmunlockall\fP(2)     2.0
 482 \fBmunmap\fP(2) 1.0
 483 \fBname_to_handle_at\fP(2)      2.6.39
 484 \fBnanosleep\fP(2)      2.0
 485 .\" 5590ff0d5528b60153c0b4e7b771472b5a95e297
 486 \fBnewfstatat\fP(2)     2.6.16  See \fBstat\fP(2)
 487 \fBnfsservctl\fP(2)     2.2     Removed in 3.1
 488 \fBnice\fP(2)   1.0
 489 \fBold_adjtimex\fP(2)   2.0     ALPA only; see NOTES
 490 \fBold_getrlimit\fP(2)  2.4     T{
 491 Old variant of \fBgetrlimit\fP(2)
 492 .br
 493 that used a different value
 494 .br
 495 for \fBRLIM_INFINITY\fP
 496 T}
 497 \fBoldfstat\fP(2)       1.0
 498 \fBoldlstat\fP(2)       1.0
 499 \fBoldolduname\fP(2)    1.0
 500 \fBoldstat\fP(2)        1.0
 501 \fBoldumount\fP(2)      2.4.116 T{
 502 Name of the old \fBumount\fP(2)
 503 .br
 504 syscall on Alpha
 505 T}
 506 \fBolduname\fP(2)       1.0
 507 \fBopen\fP(2)   1.0
 508 \fBopen_by_handle_at\fP(2)      2.6.39
 509 \fBopenat\fP(2) 2.6.16
 510 .\" 9d02a4283e9ce4e9ca11ff00615bdacdb0515a1a
 511 \fBor1k_atomic\fP(2)    3.1     OpenRISC 1000 only
 512 \fBpause\fP(2)  1.0
 513 \fBpciconfig_iobase\fP(2)       2.2.15; 2.4     Not on x86
 514 .\" Alpha, PowerPC, ARM; not x86
 515 \fBpciconfig_read\fP(2) 2.0.26; 2.2     Not on x86
 516 .\" , PowerPC, ARM; not x86
 517 \fBpciconfig_write\fP(2)        2.0.26; 2.2     Not on x86
 518 .\" , PowerPC, ARM; not x86
 519 \fBperf_event_open\fP(2)        2.6.31  T{
 520 Was perf_counter_open() in
 521 .br
 522 2.6.31; renamed in 2.6.32
 523 T}
 524 \fBpersonality\fP(2)    1.2
 525 \fBperfctr\fP(2)        2.2     SPARC only; removed in 2.6.34
 526 .\"     commit c7d5a0050773e98d1094eaa9f2a1a793fafac300 removed perfctr()
 527 \fBperfmonctl\fP(2)     2.4     IA-64 only
 528 \fBpipe\fP(2)   1.0
 529 \fBpipe2\fP(2)  2.6.27
 530 \fBpivot_root\fP(2)     2.4
 531 \fBpkey_alloc\fP(2)     4.8
 532 \fBpkey_free\fP(2)      4.8
 533 \fBpkey_mprotect\fP(2)  4.8
 534 \fBpoll\fP(2)   2.0.36; 2.2
 535 \fBppoll\fP(2)  2.6.16
 536 \fBprctl\fP(2)  2.2
 537 \fBpread\fP(2)          T{
 538 Used for \fBpread64\fP(2) on AVR32
 539 .br
 540 (port removed in Linux 4.12)
 541 .br
 542 and Blackfin (port removed
 543 .br
 544 in Linux 4.17)
 545 T}
 546 \fBpread64\fP(2)                T{
 547 Added as "pread" in 2.2;
 548 .br
 549 renamed "pread64" in 2.6
 550 T}
 551 \fBpreadv\fP(2) 2.6.30
 552 \fBpreadv2\fP(2)        4.6
 553 \fBprlimit64\fP(2)      2.6.36
 554 \fBprocess_vm_readv\fP(2)       3.2
 555 \fBprocess_vm_writev\fP(2)      3.2
 556 \fBpselect6\fP(2)       2.6.16
 557 .\" Implements \fBpselect\fP(2)
 558 \fBptrace\fP(2) 1.0
 559 \fBpwrite\fP(2)         T{
 560 Used for \fBpwrite64\fP(2) on AVR32
 561 (port removed in Linux 4.12)
 562 and Blackfin (port removed
 563 in Linux 4.17)
 564 T}
 565 \fBpwrite64\fP(2)               T{
 566 Added as "pwrite" in 2.2;
 567 .br
 568 renamed "pwrite64" in 2.6
 569 T}
 570 \fBpwritev\fP(2)        2.6.30
 571 \fBpwritev2\fP(2)       4.6
 572 \fBquery_module\fP(2)   2.2     Removed in 2.6
 573 \fBquotactl\fP(2)       1.0
 574 \fBread\fP(2)   1.0
 575 \fBreadahead\fP(2)      2.4.13
 576 \fBreaddir\fP(2)        1.0
 577 .\" Supersedes \fBgetdents\fP(2)
 578 \fBreadlink\fP(2)       1.0
 579 \fBreadlinkat\fP(2)     2.6.16
 580 \fBreadv\fP(2)  2.0
 581 \fBreboot\fP(2) 1.0
 582 \fBrecv\fP(2)   2.0     See notes on \fBsocketcall\fP(2)
 583 \fBrecvfrom\fP(2)       2.0     See notes on \fBsocketcall\fP(2)
 584 \fBrecvmsg\fP(2)        2.0     See notes on \fBsocketcall\fP(2)
 585 \fBrecvmmsg\fP(2)       2.6.33
 586 \fBremap_file_pages\fP(2)       2.6     Deprecated since 3.16
 587 \fBremovexattr\fP(2)    2.6; 2.4.18
 588 \fBrename\fP(2) 1.0
 589 \fBrenameat\fP(2)       2.6.16
 590 \fBrenameat2\fP(2)      3.15
 591 \fBrequest_key\fP(2)    2.6.10
 592 \fBrestart_syscall\fP(2)        2.6
 593 .\" 921ebd8f2c081b3cf6c3b29ef4103eef3ff26054
 594 \fBriscv_flush_icache\fP(2)     4.15    RISC-V only
 595 \fBrmdir\fP(2)  1.0
 596 \fBrseq\fP(2)   4.18
 597 \fBrt_sigaction\fP(2)   2.2
 598 \fBrt_sigpending\fP(2)  2.2
 599 \fBrt_sigprocmask\fP(2) 2.2
 600 \fBrt_sigqueueinfo\fP(2)        2.2
 601 \fBrt_sigreturn\fP(2)   2.2
 602 \fBrt_sigsuspend\fP(2)  2.2
 603 \fBrt_sigtimedwait\fP(2)        2.2
 604 \fBrt_tgsigqueueinfo\fP(2)      2.6.31
 605 \fBrtas\fP(2)   2.6.2   PowerPC/PowerPC64 only
 606 \fBs390_runtime_instr\fP(2)     3.7     s390 only
 607 \fBs390_pci_mmio_read\fP(2)     3.19    s390 only
 608 \fBs390_pci_mmio_write\fP(2)    3.19    s390 only
 609 \fBs390_sthyi\fP(2)     4.15    s390 only
 610 \fBs390_guarded_storage\fP(2)   4.12    s390 only
 611 \fBsched_get_affinity\fP(2)     2.6     T{
 612 Name of \fBsched_getaffinity\fP(2)
 613 .br
 614 on SPARC and SPARC64
 615 T}
 616 \fBsched_get_priority_max\fP(2) 2.0
 617 \fBsched_get_priority_min\fP(2) 2.0
 618 \fBsched_getaffinity\fP(2)      2.6
 619 \fBsched_getattr\fP(2)  3.14
 620 \fBsched_getparam\fP(2) 2.0
 621 \fBsched_getscheduler\fP(2)     2.0
 622 \fBsched_rr_get_interval\fP(2)  2.0
 623 \fBsched_set_affinity\fP(2)     2.6     T{
 624 Name of \fBsched_setaffinity\fP(2)
 625 .br
 626 on SPARC and SPARC64
 627 T}
 628 \fBsched_setaffinity\fP(2)      2.6
 629 \fBsched_setattr\fP(2)  3.14
 630 \fBsched_setparam\fP(2) 2.0
 631 \fBsched_setscheduler\fP(2)     2.0
 632 \fBsched_yield\fP(2)    2.0
 633 \fBseccomp\fP(2)        3.17
 634 \fBselect\fP(2) 1.0
 635 \fBsemctl\fP(2) 2.0     See notes on \fBipc\fP(2)
 636 \fBsemget\fP(2) 2.0     See notes on \fBipc\fP(2)
 637 \fBsemop\fP(2)  2.0     See notes on \fBipc\fP(2)
 638 \fBsemtimedop\fP(2)     2.6; 2.4.22
 639 \fBsend\fP(2)   2.0     See notes on \fBsocketcall\fP(2)
 640 \fBsendfile\fP(2)       2.2
 641 \fBsendfile64\fP(2)     2.6; 2.4.19
 642 \fBsendmmsg\fP(2)       3.0
 643 \fBsendmsg\fP(2)        2.0     See notes on \fBsocketcall\fP(2)
 644 \fBsendto\fP(2) 2.0     See notes on \fBsocketcall\fP(2)
 645 \fBset_mempolicy\fP(2)  2.6.6
 646 \fBset_robust_list\fP(2)        2.6.17
 647 \fBset_thread_area\fP(2)        2.6
 648 \fBset_tid_address\fP(2)        2.6
 649 \fBset_tls\fP(2)        2.6.11  T{
 650 ARM OABI/EABI only (constant
 651 .br
 652 has \fB__ARM_NR\fP prefix)
 653 T}
 654 \fBsetaltroot\fP(2)     2.6.10  T{
 655 Removed in 2.6.11, exposed one
 656 of implementation details of
 657 \fBpersonality\fP(2) (creating an
 658 alternative root, precursor of
 659 mount namespaces) to user space.
 660 T}
 661 .\" See http://lkml.org/lkml/2005/8/1/83
 662 .\" "[PATCH] remove sys_set_zone_reclaim()"
 663 \fBsetdomainname\fP(2)  1.0
 664 \fBsetfsgid\fP(2)       1.2
 665 \fBsetfsgid32\fP(2)     2.4
 666 \fBsetfsuid\fP(2)       1.2
 667 \fBsetfsuid32\fP(2)     2.4
 668 \fBsetgid\fP(2) 1.0
 669 \fBsetgid32\fP(2)       2.4
 670 \fBsetgroups\fP(2)      1.0
 671 \fBsetgroups32\fP(2)    2.4
 672 .\" arch/alpha/include/asm/core_lca.h
 673 \fBsethae\fP(2) 2.0     Alph only; see NOTES
 674 \fBsethostname\fP(2)    1.0
 675 \fBsetitimer\fP(2)      1.0
 676 \fBsetns\fP(2)  3.0
 677 \fBsetpgid\fP(2)        1.0
 678 \fBsetpgrp\fP(2)        2.0     T{
 679 Alternative name for
 680 .br
 681 \fBsetpgid\fP(2) on Alpha
 682 T}
 683 \fBsetpriority\fP(2)    1.0
 684 \fBsetregid\fP(2)       1.0
 685 \fBsetregid32\fP(2)     2.4
 686 \fBsetresgid\fP(2)      2.2
 687 \fBsetresgid32\fP(2)    2.4
 688 \fBsetresuid\fP(2)      2.2
 689 \fBsetresuid32\fP(2)    2.4
 690 \fBsetreuid\fP(2)       1.0
 691 \fBsetreuid32\fP(2)     2.4
 692 \fBsetrlimit\fP(2)      1.0
 693 \fBsetsid\fP(2) 1.0
 694 \fBsetsockopt\fP(2)     2.0     See notes on \fBsocketcall\fP(2)
 695 \fBsettimeofday\fP(2)   1.0
 696 \fBsetuid\fP(2) 1.0
 697 \fBsetuid32\fP(2)       2.4
 698 \fBsetup\fP(2)  1.0     Removed in 2.2
 699 \fBsetxattr\fP(2)       2.6; 2.4.18
 700 \fBsgetmask\fP(2)       1.0
 701 \fBshmat\fP(2)  2.0     See notes on \fBipc\fP(2)
 702 \fBshmctl\fP(2) 2.0     See notes on \fBipc\fP(2)
 703 \fBshmdt\fP(2)  2.0     See notes on \fBipc\fP(2)
 704 \fBshmget\fP(2) 2.0     See notes on \fBipc\fP(2)
 705 \fBshutdown\fP(2)       2.0     See notes on \fBsocketcall\fP(2)
 706 \fBsigaction\fP(2)      1.0
 707 \fBsigaltstack\fP(2)    2.2
 708 \fBsignal\fP(2) 1.0
 709 \fBsignalfd\fP(2)       2.6.22
 710 \fBsignalfd4\fP(2)      2.6.27
 711 \fBsigpending\fP(2)     1.0
 712 \fBsigprocmask\fP(2)    1.0
 713 \fBsigreturn\fP(2)      1.0
 714 \fBsigsuspend\fP(2)     1.0
 715 \fBsocket\fP(2) 2.0     See notes on \fBsocketcall\fP(2)
 716 \fBsocketcall\fP(2)     1.0
 717 .\" Implements BSD socket calls
 718 \fBsocketpair\fP(2)     2.0     See notes on \fBsocketcall\fP(2)
 719 .\" 5a0015d62668e64c8b6e02e360fbbea121bfd5e6
 720 \fBspill\fP(2)  2.6.13  Xtensa only
 721 \fBsplice\fP(2) 2.6.17
 722 \fBspu_create\fP(2)     2.6.16  PowerPC/PowerPC64 only
 723 \fBspu_run\fP(2)        2.6.16  PowerPC/PowerPC64 only
 724 \fBsram_alloc\fP(2)     2.6.22  T{
 725 Blackfin (port removed
 726 .br
 727 in Linux 4.17)
 728 T}
 729 \fBsram_free\fP(2)      2.6.22  T{
 730 Blackfin (port removed
 731 .br
 732 in Linux 4.17)
 733 T}
 734 \fBssetmask\fP(2)       1.0
 735 \fBstat\fP(2)   1.0
 736 \fBstat64\fP(2) 2.4
 737 \fBstatfs\fP(2) 1.0
 738 \fBstatfs64\fP(2)       2.6
 739 \fBstatx\fP(2)  4.11
 740 \fBstime\fP(2)  1.0
 741 \fBsubpage_prot\fP(2)   2.6.25  PowerPC/PowerPC64 only
 742 \fBswapcontext\fP(2)    2.6.3   PowerPC/PowerPC64 only
 743 .\" 529d235a0e190ded1d21ccc80a73e625ebcad09b
 744 \fBswitch_endian\fP(2)  4.1     PowerPC64 only
 745 \fBswapcontext\fP(2)    2.6.3   PowerPC only
 746 \fBswapoff\fP(2)        1.0
 747 \fBswapon\fP(2) 1.0
 748 \fBsymlink\fP(2)        1.0
 749 \fBsymlinkat\fP(2)      2.6.16
 750 \fBsync\fP(2)   1.0
 751 \fBsync_file_range\fP(2)        2.6.17
 752 \fBsync_file_range2\fP(2)       2.6.22
 753 .\" PowerPC, ARM, tile
 754 .\" First appeared on ARM, as arm_sync_file_range(), but later renamed
 755 .\" \fBsys_debug_setcontext\fP(2)       ???     PowerPC if CONFIG_PPC32
 756 \fBsyncfs\fP(2) 2.6.39
 757 \fBsys_debug_setcontext\fP(2)   2.6.11  PowerPC only
 758 \fBsyscall\fP(2)        1.0     T{
 759 Still available on ARM OABI
 760 .br
 761 and MIPS O32 ABI
 762 T}
 763 \fBsysfs\fP(2)  1.2
 764 \fBsysinfo\fP(2)        1.0
 765 \fBsyslog\fP(2) 1.0
 766 .\" glibc interface is \fBklogctl\fP(3)
 767 \fBsysmips\fP(2)        2.6.0   MIPS only
 768 \fBtee\fP(2)    2.6.17
 769 \fBtgkill\fP(2) 2.6
 770 \fBtime\fP(2)   1.0
 771 \fBtimer_create\fP(2)   2.6
 772 \fBtimer_delete\fP(2)   2.6
 773 \fBtimer_getoverrun\fP(2)       2.6
 774 \fBtimer_gettime\fP(2)  2.6
 775 \fBtimer_settime\fP(2)  2.6
 776 .\" b215e283992899650c4271e7385c79e26fb9a88e
 777 .\" 4d672e7ac79b5ec5cdc90e450823441e20464691
 778 \fBtimerfd\fP(2)        2.6.22  T{
 779 Old timerfd interface,
 780 removed in 2.6.25
 781 T}
 782 \fBtimerfd_create\fP(2) 2.6.25
 783 \fBtimerfd_gettime\fP(2)        2.6.25
 784 \fBtimerfd_settime\fP(2)        2.6.25
 785 \fBtimes\fP(2)  1.0
 786 \fBtkill\fP(2)  2.6; 2.4.22
 787 \fBtruncate\fP(2)       1.0
 788 \fBtruncate64\fP(2)     2.4
 789 \fBugetrlimit\fP(2)     2.4
 790 \fBumask\fP(2)  1.0
 791 \fBumount\fP(2) 1.0
 792 .\" sys_oldumount() -- __NR_umount
 793 \fBumount2\fP(2)        2.2
 794 .\" sys_umount() -- __NR_umount2
 795 \fBuname\fP(2)  1.0
 796 \fBunlink\fP(2) 1.0
 797 \fBunlinkat\fP(2)       2.6.16
 798 \fBunshare\fP(2)        2.6.16
 799 \fBuselib\fP(2) 1.0
 800 \fBustat\fP(2)  1.0
 801 \fBuserfaultfd\fP(2)    4.3
 802 \fBusr26\fP(2)  2.4.8.1 ARM OABI only
 803 \fBusr32\fP(2)  2.4.8.1 ARM OABI only
 804 \fButime\fP(2)  1.0
 805 \fButimensat\fP(2)      2.6.22
 806 \fButimes\fP(2) 2.2
 807 \fButrap_install\fP(2)  2.2     SPARC64 only
 808 .\" FIXME . document utrap_install()
 809 .\" There's a man page for Solaris 5.11
 810 \fBvfork\fP(2)  2.2
 811 \fBvhangup\fP(2)        1.0
 812 \fBvm86old\fP(2)        1.0     T{
 813 Was "vm86"; renamed in
 814 2.0.28/2.2
 815 T}
 816 \fBvm86\fP(2)   2.0.28; 2.2
 817 \fBvmsplice\fP(2)       2.6.17
 818 \fBwait4\fP(2)  1.0
 819 \fBwaitid\fP(2) 2.6.10
 820 \fBwaitpid\fP(2)        1.0
 821 \fBwrite\fP(2)  1.0
 822 \fBwritev\fP(2) 2.0
 823 .\" 5a0015d62668e64c8b6e02e360fbbea121bfd5e6
 824 \fBxtensa\fP(2) 2.6.13  Xtensa only
 825 .TE
 826 .ad
 827 .PP
 828 On many platforms, including x86-32, socket calls are all multiplexed
 829 (via glibc wrapper functions) through
 830 .BR socketcall (2)
 831 and similarly System\ V IPC calls are multiplexed through
 832 .BR ipc (2).
 833 .PP
 834 Although slots are reserved for them in the system call table,
 835 the following system calls are not implemented in the standard kernel:
 836 .BR afs_syscall (2), \" __NR_afs_syscall is 53 on Linux 2.6.22/i386
 837 .BR break (2),       \" __NR_break is 17 on Linux 2.6.22/i386
 838 .BR ftime (2),       \" __NR_ftime is 35 on Linux 2.6.22/i386
 839 .BR getpmsg (2),     \" __NR_getpmsg is 188 on Linux 2.6.22/i386
 840 .BR gtty (2),        \" __NR_gtty is 32 on Linux 2.6.22/i386
 841 .BR idle (2),        \" __NR_idle is 112 on Linux 2.6.22/i386
 842 .BR lock (2),        \" __NR_lock is 53 on Linux 2.6.22/i386
 843 .BR madvise1 (2),    \" __NR_madvise1 is 219 on Linux 2.6.22/i386
 844 .BR mpx (2),         \" __NR_mpx is 66 on Linux 2.6.22/i386
 845 .BR phys (2),        \" Slot has been reused
 846 .BR prof (2),        \" __NR_prof is 44 on Linux 2.6.22/i386
 847 .BR profil (2),      \" __NR_profil is 98 on Linux 2.6.22/i386
 848 .BR putpmsg (2),     \" __NR_putpmsg is 189 on Linux 2.6.22/i386
 849 .\" __NR_security is 223 on Linux 2.4/i386; absent on 2.6/i386, present
 850 .\" on a couple of 2.6 architectures
 851 .BR security (2),    \" __NR_security is 223 on Linux 2.4/i386
 852 .\" The security call is for future use.
 853 .BR stty (2),        \" __NR_stty is 31 on Linux 2.6.22/i386
 854 .BR tuxcall (2),     \" __NR_tuxcall is 184 on x86_64, also on PPC and alpha
 855 .BR ulimit (2),      \" __NR_ulimit is 58 on Linux 2.6.22/i386
 856 and
 857 .BR vserver (2)      \" __NR_vserver is 273 on Linux 2.6.22/i386
 858 (see also
 859 .BR unimplemented (2)).
 860 However,
 861 .BR ftime (3),
 862 .BR profil (3),
 863 and
 864 .BR ulimit (3)
 865 exist as library routines.
 866 The slot for
 867 .BR phys (2)
 868 is in use since kernel 2.1.116 for
 869 .BR umount (2);
 870 .BR phys (2)
 871 will never be implemented.
 872 The
 873 .BR getpmsg (2)
 874 and
 875 .BR putpmsg (2)
 876 calls are for kernels patched to support STREAMS,
 877 and may never be in the standard kernel.
 878 .PP
 879 There was briefly
 880 .BR set_zone_reclaim (2),
 881 added in Linux 2.6.13, and removed in 2.6.16;
 882 this system call was never available to user space.
 883 .SH NOTES
 884 .PP
 885 Roughly speaking, the code belonging to the system call
 886 with number __NR_xxx defined in
 887 .I /usr/include/asm/unistd.h
 888 can be found in the Linux kernel source in the routine
 889 .IR sys_xxx ().
 890 (The dispatch table for i386 can be found in
 891 .IR /usr/src/linux/arch/i386/kernel/entry.S .)
 892 There are many exceptions, however, mostly because
 893 older system calls were superseded by newer ones,
 894 and this has been treated somewhat unsystematically.
 895 On platforms with
 896 proprietary operating-system emulation,
 897 such as sparc, sparc64, and alpha,
 898 there are many additional system calls; mips64 also contains a full
 899 set of 32-bit system calls.
 900 .PP
 901 Over time, changes to the interfaces of some system calls have been
 902 necessary.
 903 One reason for such changes was the need to increase the size of
 904 structures or scalar values passed to the system call.
 905 Because of these changes, certain architectures
 906 (notably, longstanding 32-bit architectures such as i386)
 907 now have various groups of related system calls (e.g.,
 908 .BR truncate (2)
 909 and
 910 .BR truncate64 (2))
 911 which perform similar tasks, but which vary in
 912 details such as the size of their arguments.
 913 (As noted earlier, applications are generally unaware of this:
 914 the glibc wrapper functions do some work to ensure that the right
 915 system call is invoked, and that ABI compatibility is
 916 preserved for old binaries.)
 917 Examples of systems calls that exist in multiple versions are
 918 the following:
 919 .IP * 3
 920 By now there are three different versions of
 921 .BR stat (2):
 922 .IR sys_stat ()
 923 (slot
 924 .IR __NR_oldstat ),
 925 .IR sys_newstat ()
 926 (slot
 927 .IR __NR_stat ),
 928 and
 929 .IR sys_stat64 ()
 930 (slot
 931 .IR __NR_stat64 ),
 932 with the last being the most current.
 933 .\" e.g., on 2.6.22/i386: __NR_oldstat 18, __NR_stat 106, __NR_stat64 195
 934 .\" The stat system calls deal with three different data structures,
 935 .\" defined in include/asm-i386/stat.h: __old_kernel_stat, stat, stat64
 936 A similar story applies for
 937 .BR lstat (2)
 938 and
 939 .BR fstat (2).
 940 .IP *
 941 Similarly, the defines
 942 .IR __NR_oldolduname ,
 943 .IR __NR_olduname ,
 944 and
 945 .I __NR_uname
 946 refer to the routines
 947 .IR sys_olduname (),
 948 .IR sys_uname ()
 949 and
 950 .IR sys_newuname ().
 951 .IP *
 952 In Linux 2.0, a new version of
 953 .BR vm86 (2)
 954 appeared, with the old and the new kernel routines being named
 955 .IR sys_vm86old ()
 956 and
 957 .IR sys_vm86 ().
 958 .IP *
 959 In Linux 2.4, a new version of
 960 .BR getrlimit (2)
 961 appeared, with the old and the new kernel routines being named
 962 .IR sys_old_getrlimit ()
 963 (slot
 964 .IR __NR_getrlimit )
 965 and
 966 .IR sys_getrlimit ()
 967 (slot
 968 .IR __NR_ugetrlimit ).
 969 .IP *
 970 Linux 2.4 increased the size of user and group IDs from 16 to 32 bits.
 971 .\" 64-bit off_t changes: ftruncate64, *stat64,
 972 .\" fcntl64 (because of the flock structure), getdents64, *statfs64
 973 To support this change, a range of system calls were added
 974 (e.g.,
 975 .BR chown32 (2),
 976 .BR getuid32 (2),
 977 .BR getgroups32 (2),
 978 .BR setresuid32 (2)),
 979 superseding earlier calls of the same name without the
 980 "32" suffix.
 981 .IP *
 982 Linux 2.4 added support for applications on 32-bit architectures
 983 to access large files (i.e., files for which the sizes and
 984 file offsets can't be represented in 32 bits.)
 985 To support this change, replacements were required for system calls
 986 that deal with file offsets and sizes.
 987 Thus the following system calls were added:
 988 .BR fcntl64 (2),
 989 .BR getdents64 (2),
 990 .BR stat64 (2),
 991 .BR statfs64 (2),
 992 .BR truncate64 (2),
 993 and their analogs that work with file descriptors or
 994 symbolic links.
 995 These system calls supersede the older system calls
 996 which, except in the case of the "stat" calls,
 997 have the same name without the "64" suffix.
 998 .IP
 999 On newer platforms that only have 64-bit file access and 32-bit UIDs/GIDs
1000 (e.g., alpha, ia64, s390x, x86-64), there is just a single version of
1001 the UID/GID and file access system calls.
1002 On platforms (typically, 32-bit platforms) where the *64 and *32 calls exist,
1003 the other versions are obsolete.
1004 .IP *
1005 The
1006 .I rt_sig*
1007 calls were added in kernel 2.2 to support the addition
1008 of real-time signals (see
1009 .BR signal (7)).
1010 These system calls supersede the older system calls of the same
1011 name without the "rt_" prefix.
1012 .IP *
1013 The
1014 .BR select (2)
1015 and
1016 .BR mmap (2)
1017 system calls use five or more arguments,
1018 which caused problems in the way
1019 argument passing on the i386 used to be set up.
1020 Thus, while other architectures have
1021 .IR sys_select ()
1022 and
1023 .IR sys_mmap ()
1024 corresponding to
1025 .I __NR_select
1026 and
1027 .IR __NR_mmap ,
1028 on i386 one finds
1029 .IR old_select ()
1030 and
1031 .IR old_mmap ()
1032 (routines that use a pointer to an
1033 argument block) instead.
1034 These days passing five arguments
1035 is not a problem any more, and there is a
1036 .I __NR__newselect
1037 .\" (used by libc 6)
1038 that corresponds directly to
1039 .IR sys_select ()
1040 and similarly
1041 .IR __NR_mmap2 .
1042 s390x is the only 64-bit architecture that has
1043 .IR old_mmap ().
1044 .\" .PP
1045 .\" Two system call numbers,
1046 .\" .IR __NR__llseek
1047 .\" and
1048 .\" .IR __NR__sysctl
1049 .\" have an additional underscore absent in
1050 .\" .IR sys_llseek ()
1051 .\" and
1052 .\" .IR sys_sysctl ().
1053 .\"
1054 .\" In kernel 2.1.81,
1055 .\" .BR lchown (2)
1056 .\" and
1057 .\" .BR chown (2)
1058 .\" were swapped; that is,
1059 .\" .BR lchown (2)
1060 .\" was added with the semantics that were then current for
1061 .\" .BR chown (2),
1062 .\" and the semantics of the latter call were changed to what
1063 .\" they are today.
1064 .\"
1065 .\"
1066 .SS "Architecture-specific details: Alpha"
1067 .IP * 3
1068 .BR getxgid (2)
1069 returns a pair of GID and effective GID via registers
1070 \fBr0\fP and \fBr20\fP; it is provided
1071 instead of
1072 \fBgetgid\fP(2) and \fBgetegid\fP(2).
1073 .IP *
1074 .BR getxpid (2)
1075 returns a pair of PID and parent PID via registers
1076 \fBr0\fP and \fBr20\fP; it is provided instead of
1077 \fBgetpid\fP(2) and \fBgetppid\fP(2).
1078 .IP *
1079 .BR old_adjtimex (2)
1080 is a variant of \fBadjtimex\fP(2) that uses \fIstruct timeval32\fP,
1081 for compatibility with OSF/1.
1082 .IP *
1083 .BR getxuid (2)
1084 returns a pair of GID and effective GID via registers
1085 \fBr0\fP and \fBr20\fP; it is provided instead of
1086 \fBgetuid\fP(2) and \fBgeteuid\fP(2).
1087 .IP *
1088 .BR sethae (2)
1089 is used for configuring the Host Address Extension register on
1090 low-cost Alphas in order to access address space beyond first 27 bits.
1091 .SH SEE ALSO
1092 .BR intro (2),
1093 .BR syscall (2),
1094 .BR unimplemented (2),
1095 .BR errno (3),
1096 .BR libc (7),
1097 .BR vdso (7)