man2/syscalls.2

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   2 .\" with some input from Stepan Kasal <kasal@ucw.cz>
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  31 .TH SYSCALLS 2 2020-04-11 "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; and the 5.x kernel series,
 140 which followed on from kernel 4.20.
 141 .IP *
 142 In some cases, a system call was added to a stable kernel
 143 series after it branched from the previous stable kernel
 144 series, and then backported into the earlier stable kernel series.
 145 For example some system calls that appeared in 2.6.x were also backported
 146 into a 2.4.x release after 2.4.15.
 147 When this is so, the version where the system call appeared
 148 in both of the major kernel series is listed.
 149 .PP
 150 The list of system calls that are available as at kernel 4.19
 151 (or in a few cases only on older kernels) is as follows:
 152 .\"
 153 .\" Looking at scripts/checksyscalls.sh in the kernel source is
 154 .\" instructive about x86 specifics.
 155 .\"
 156 .ad l
 157 .TS
 158 l2 le l
 159 ---
 160 l l l.
 161 \fBSystem call\fP       \fBKernel\fP    \fBNotes\fP
 162
 163 \fB_llseek\fP(2)        1.2
 164 \fB_newselect\fP(2)     2.0
 165 \fB_sysctl\fP(2)        2.0
 166 \fBaccept\fP(2) 2.0     See notes on \fBsocketcall\fP(2)
 167 \fBaccept4\fP(2)        2.6.28
 168 \fBaccess\fP(2) 1.0
 169 \fBacct\fP(2)   1.0
 170 \fBadd_key\fP(2)        2.6.10
 171 \fBadjtimex\fP(2)       1.0
 172 \fBalarm\fP(2)  1.0
 173 \fBalloc_hugepages\fP(2)        2.5.36  Removed in 2.5.44
 174 .\" 4adeefe161a74369e44cc8e663f240ece0470dc3
 175 \fBarc_gettls\fP(2)     3.9     ARC only
 176 \fBarc_settls\fP(2)     3.9     ARC only
 177 .\" 91e040a79df73d371f70792f30380d4e44805250
 178 \fBarc_usr_cmpxchg\fP(2)        4.9     ARC only
 179 .\" x86: 79170fda313ed5be2394f87aa2a00d597f8ed4a1
 180 \fBarch_prctl\fP(2)     2.6     x86_64, x86 since 4.12
 181 .\" 9674cdc74d63f346870943ef966a034f8c71ee57
 182 \fBatomic_barrier\fP(2) 2.6.34  m68k only
 183 \fBatomic_cmpxchg_32\fP(2)      2.6.34  m68k only
 184 \fBbdflush\fP(2)        1.2     T{
 185 Deprecated (does nothing)
 186 .br
 187 since 2.6
 188 T}
 189 \fBbfin_spinlock\fP(2)  2.6.22  T{
 190 Blackfin only (port removed
 191 .br
 192 in Linux 4.17)
 193 T}
 194 \fBbind\fP(2)   2.0     See notes on \fBsocketcall\fP(2)
 195 \fBbpf\fP(2)    3.18
 196 \fBbrk\fP(2)    1.0
 197 \fBbreakpoint\fP(2)     2.2     T{
 198 ARM OABI only, defined with
 199 .br
 200 \fB__ARM_NR\fP prefix
 201 T}
 202 \fBcacheflush\fP(2)     1.2     Not on x86
 203 \fBcapget\fP(2) 2.2
 204 \fBcapset\fP(2) 2.2
 205 \fBchdir\fP(2)  1.0
 206 \fBchmod\fP(2)  1.0
 207 \fBchown\fP(2)  2.2     T{
 208 See \fBchown\fP(2) for
 209 .br
 210 version details
 211 T}
 212 \fBchown32\fP(2)        2.4
 213 \fBchroot\fP(2) 1.0
 214 \fBclock_adjtime\fP(2)  2.6.39
 215 \fBclock_getres\fP(2)   2.6
 216 \fBclock_gettime\fP(2)  2.6
 217 \fBclock_nanosleep\fP(2)        2.6
 218 \fBclock_settime\fP(2)  2.6
 219 \fBclone2\fP(2) 2.4     IA-64 only
 220 \fBclone\fP(2)  1.0
 221 \fBclone3\fP(2) 5.3
 222 \fBclose\fP(2)  1.0
 223 .\" .\" dcef1f634657dabe7905af3ccda12cf7f0b6fcc1
 224 .\" .\" cc20d42986d5807cbe4f5c7c8e3dab2e59ea0db3
 225 .\" .\" db695c0509d6ec9046ee5e4c520a19fa17d9fce2
 226 .\" \fBcmpxchg\fP(2)    2.6.12  T{
 227 .\" ARM, syscall constant never was
 228 .\" .br
 229 .\" exposed to userspace, in-kernel
 230 .\" .br
 231 .\" definition had \fB__ARM_NR\fP prefix,
 232 .\" .br
 233 .\" removed in 4.4
 234 .\" T}
 235 .\" 867e359b97c970a60626d5d76bbe2a8fadbf38fb
 236 .\" bb9d812643d8a121df7d614a2b9c60193a92deb0
 237 \fBcmpxchg_badaddr\fP(2)        2.6.36  T{
 238 Tile only (port removed
 239 .br
 240 in Linux 4.17)
 241 T}
 242 \fBconnect\fP(2)        2.0     See notes on \fBsocketcall\fP(2)
 243 \fBcopy_file_range\fP(2)        4.5
 244 \fBcreat\fP(2)  1.0
 245 \fBcreate_module\fP(2)  1.0     Removed in 2.6
 246 \fBdelete_module\fP(2)  1.0
 247 .\" 1394f03221790a988afc3e4b3cb79f2e477246a9
 248 .\" 4ba66a9760722ccbb691b8f7116cad2f791cca7b
 249 \fBdma_memcpy\fP(2)     2.6.22  T{
 250 Blackfin only (port removed
 251 .br
 252 in Linux 4.17)
 253 T}
 254 \fBdup\fP(2)    1.0
 255 \fBdup2\fP(2)   1.0
 256 \fBdup3\fP(2)   2.6.27
 257 \fBepoll_create\fP(2)   2.6
 258 \fBepoll_create1\fP(2)  2.6.27
 259 \fBepoll_ctl\fP(2)      2.6
 260 \fBepoll_pwait\fP(2)    2.6.19
 261 \fBepoll_wait\fP(2)     2.6
 262 \fBeventfd\fP(2)        2.6.22
 263 \fBeventfd2\fP(2)       2.6.27
 264 \fBexecv\fP(2)  2.0     T{
 265 SPARC/SPARC64 only, for
 266 .br
 267 compatibility with SunOS
 268 T}
 269 \fBexecve\fP(2) 1.0
 270 \fBexecveat\fP(2)       3.19
 271 \fBexit\fP(2)   1.0
 272 \fBexit_group\fP(2)     2.6
 273 \fBfaccessat\fP(2)      2.6.16
 274 \fBfadvise64\fP(2)      2.6
 275 .\" Implements \fBposix_fadvise\fP(2)
 276 \fBfadvise64_64\fP(2)   2.6
 277 \fBfallocate\fP(2)      2.6.23
 278 \fBfanotify_init\fP(2)  2.6.37
 279 \fBfanotify_mark\fP(2)  2.6.37
 280 .\" The fanotify calls were added in Linux 2.6.36,
 281 .\" but disabled while the API was finalized.
 282 \fBfchdir\fP(2) 1.0
 283 \fBfchmod\fP(2) 1.0
 284 \fBfchmodat\fP(2)       2.6.16
 285 \fBfchown\fP(2) 1.0
 286 \fBfchown32\fP(2)       2.4
 287 \fBfchownat\fP(2)       2.6.16
 288 \fBfcntl\fP(2)  1.0
 289 \fBfcntl64\fP(2)        2.4
 290 \fBfdatasync\fP(2)      2.0
 291 \fBfgetxattr\fP(2)      2.6; 2.4.18
 292 \fBfinit_module\fP(2)   3.8
 293 \fBflistxattr\fP(2)     2.6; 2.4.18
 294 \fBflock\fP(2)  2.0
 295 \fBfork\fP(2)   1.0
 296 \fBfree_hugepages\fP(2) 2.5.36  Removed in 2.5.44
 297 \fBfremovexattr\fP(2)   2.6; 2.4.18
 298 \fBfsconfig\fP(2)       5.2
 299 \fBfsetxattr\fP(2)      2.6; 2.4.18
 300 \fBfsmount\fP(2)        5.2
 301 \fBfsopen\fP(2) 5.2
 302 \fBfspick\fP(2) 5.2
 303 \fBfstat\fP(2)  1.0
 304 \fBfstat64\fP(2)        2.4
 305 \fBfstatat64\fP(2)      2.6.16
 306 \fBfstatfs\fP(2)        1.0
 307 \fBfstatfs64\fP(2)      2.6
 308 \fBfsync\fP(2)  1.0
 309 \fBftruncate\fP(2)      1.0
 310 \fBftruncate64\fP(2)    2.4
 311 \fBfutex\fP(2)  2.6
 312 \fBfutimesat\fP(2)      2.6.16
 313 \fBget_kernel_syms\fP(2)        1.0     Removed in 2.6
 314 \fBget_mempolicy\fP(2)  2.6.6
 315 \fBget_robust_list\fP(2)        2.6.17
 316 \fBget_thread_area\fP(2)        2.6
 317 .\" 8fcd6c45f5a65621ec809b7866a3623e9a01d4ed
 318 \fBget_tls\fP(2)        4.15    T{
 319 ARM OABI only, has
 320 .br
 321 \fB__ARM_NR\fP prefix
 322 T}
 323 \fBgetcpu\fP(2) 2.6.19
 324 \fBgetcwd\fP(2) 2.2
 325 \fBgetdents\fP(2)       2.0
 326 \fBgetdents64\fP(2)     2.4
 327 .\" parisc: 863722e856e64dae0e252b6bb546737c6c5626ce
 328 \fBgetdomainname\fP(2)  2.2     T{
 329 SPARC, SPARC64; available
 330 .br
 331 as \fBosf_getdomainname\fP(2)
 332 .br
 333 on Alpha since Linux 2.0
 334 T}
 335 .\" ec98c6b9b47df6df1c1fa6cf3d427414f8c2cf16
 336 \fBgetdtablesize\fP(2)  2.0     T{
 337 SPARC (removed in 2.6.26),
 338 .br
 339 available on Alpha as
 340 .br
 341 \fBosf_getdtablesize\fP(2)
 342 T}
 343 \fBgetegid\fP(2)        1.0
 344 \fBgetegid32\fP(2)      2.4
 345 \fBgeteuid\fP(2)        1.0
 346 \fBgeteuid32\fP(2)      2.4
 347 \fBgetgid\fP(2) 1.0
 348 \fBgetgid32\fP(2)       2.4
 349 \fBgetgroups\fP(2)      1.0
 350 \fBgetgroups32\fP(2)    2.4
 351 .\" SPARC removal: ec98c6b9b47df6df1c1fa6cf3d427414f8c2cf16
 352 \fBgethostname\fP(2)    2.0     T{
 353 Alpha, was available on
 354 .br
 355 SPARC up to Linux 2.6.26
 356 T}
 357 \fBgetitimer\fP(2)      1.0
 358 \fBgetpeername\fP(2)    2.0     See notes on \fBsocketcall\fP(2)
 359 \fBgetpagesize\fP(2)    2.0     Not on x86
 360 \fBgetpgid\fP(2)        1.0
 361 \fBgetpgrp\fP(2)        1.0
 362 \fBgetpid\fP(2) 1.0
 363 \fBgetppid\fP(2)        1.0
 364 \fBgetpriority\fP(2)    1.0
 365 \fBgetrandom\fP(2)      3.17
 366 \fBgetresgid\fP(2)      2.2
 367 \fBgetresgid32\fP(2)    2.4
 368 \fBgetresuid\fP(2)      2.2
 369 \fBgetresuid32\fP(2)    2.4
 370 \fBgetrlimit\fP(2)      1.0
 371 \fBgetrusage\fP(2)      1.0
 372 \fBgetsid\fP(2) 2.0
 373 \fBgetsockname\fP(2)    2.0     See notes on \fBsocketcall\fP(2)
 374 \fBgetsockopt\fP(2)     2.0     See notes on \fBsocketcall\fP(2)
 375 \fBgettid\fP(2) 2.4.11
 376 \fBgettimeofday\fP(2)   1.0
 377 \fBgetuid\fP(2) 1.0
 378 \fBgetuid32\fP(2)       2.4
 379 \fBgetunwind\fP(2)      2.4.8   IA-64 only; deprecated
 380 \fBgetxattr\fP(2)       2.6; 2.4.18
 381 \fBgetxgid\fP(2)        2.0     Alpha only; see NOTES
 382 \fBgetxpid\fP(2)        2.0     Alpha only; see NOTES
 383 \fBgetxuid\fP(2)        2.0     Alpha only; see NOTES
 384 \fBinit_module\fP(2)    1.0
 385 \fBinotify_add_watch\fP(2)      2.6.13
 386 \fBinotify_init\fP(2)   2.6.13
 387 \fBinotify_init1\fP(2)  2.6.27
 388 \fBinotify_rm_watch\fP(2)       2.6.13
 389 \fBio_cancel\fP(2)      2.6
 390 \fBio_destroy\fP(2)     2.6
 391 \fBio_getevents\fP(2)   2.6
 392 \fBio_pgetevents\fP(2)  4.18
 393 \fBio_setup\fP(2)       2.6
 394 \fBio_submit\fP(2)      2.6
 395 \fBio_uring_enter\fP(2) 5.1
 396 \fBio_uring_register\fP(2)      5.1
 397 \fBio_uring_setup\fP(2) 5.1
 398 \fBioctl\fP(2)  1.0
 399 \fBioperm\fP(2) 1.0
 400 \fBiopl\fP(2)   1.0
 401 \fBioprio_get\fP(2)     2.6.13
 402 \fBioprio_set\fP(2)     2.6.13
 403 \fBipc\fP(2)    1.0
 404 .\" Implements System V IPC calls
 405 \fBkcmp\fP(2)   3.5
 406 \fBkern_features\fP(2)  3.7     SPARC64 only
 407 .\" FIXME . document kern_features():
 408 .\" commit 517ffce4e1a03aea979fe3a18a3dd1761a24fafb
 409 \fBkexec_file_load\fP(2)        3.17
 410 \fBkexec_load\fP(2)     2.6.13
 411 .\" The entry in the syscall table was reserved starting in 2.6.7
 412 .\" Was named sys_kexec_load() from 2.6.7 to 2.6.16
 413 \fBkeyctl\fP(2) 2.6.10
 414 \fBkill\fP(2)   1.0
 415 \fBlchown\fP(2) 1.0     T{
 416 See \fBchown\fP(2) for
 417 .br
 418 version details
 419 T}
 420 \fBlchown32\fP(2)       2.4
 421 \fBlgetxattr\fP(2)      2.6; 2.4.18
 422 \fBlink\fP(2)   1.0
 423 \fBlinkat\fP(2) 2.6.16
 424 \fBlisten\fP(2) 2.0     See notes on \fBsocketcall\fP(2)
 425 \fBlistxattr\fP(2)      2.6; 2.4.18
 426 \fBllistxattr\fP(2)     2.6; 2.4.18
 427 \fBlookup_dcookie\fP(2) 2.6
 428 \fBlremovexattr\fP(2)   2.6; 2.4.18
 429 \fBlseek\fP(2)  1.0
 430 \fBlsetxattr\fP(2)      2.6; 2.4.18
 431 \fBlstat\fP(2)  1.0
 432 \fBlstat64\fP(2)        2.4
 433 \fBmadvise\fP(2)        2.4
 434 \fBmbind\fP(2)  2.6.6
 435 \fBmemory_ordering\fP(2)        2.2     SPARC64 only
 436 .\" 26025bbfbba33a9425be1b89eccb4664ea4c17b6
 437 .\" bb6fb6dfcc17cddac11ac295861f7608194447a7
 438 \fBmetag_get_tls\fP(2)  3.9     T{
 439 Metag only (port removed
 440 .br
 441 in Linux 4.17)
 442 T}
 443 \fBmetag_set_fpu_flags\fP(2)    3.9     T{
 444 Metag only (port removed
 445 .br
 446 in Linux 4.17)
 447 T}
 448 \fBmetag_set_tls\fP(2)  3.9     T{
 449 Metag only (port removed
 450 .br
 451 in Linux 4.17)
 452 T}
 453 \fBmetag_setglobalbit\fP(2)     3.9     T{
 454 Metag only (port removed
 455 .br
 456 in Linux 4.17)
 457 T}
 458 \fBmembarrier\fP(2)     3.17
 459 \fBmemfd_create\fP(2)   3.17
 460 \fBmigrate_pages\fP(2)  2.6.16
 461 \fBmincore\fP(2)        2.4
 462 \fBmkdir\fP(2)  1.0
 463 \fBmkdirat\fP(2)        2.6.16
 464 \fBmknod\fP(2)  1.0
 465 \fBmknodat\fP(2)        2.6.16
 466 \fBmlock\fP(2)  2.0
 467 \fBmlock2\fP(2) 4.4
 468 \fBmlockall\fP(2)       2.0
 469 \fBmmap\fP(2)   1.0
 470 \fBmmap2\fP(2)  2.4
 471 \fBmodify_ldt\fP(2)     1.0
 472 \fBmount\fP(2)  1.0
 473 \fBmove_mount\fP(2)     5.2
 474 \fBmove_pages\fP(2)     2.6.18
 475 \fBmprotect\fP(2)       1.0
 476 \fBmq_getsetattr\fP(2)  2.6.6
 477 .\" Implements \fBmq_getattr\fP(3) and \fBmq_setattr\fP(3)
 478 \fBmq_notify\fP(2)      2.6.6
 479 \fBmq_open\fP(2)        2.6.6
 480 \fBmq_timedreceive\fP(2)        2.6.6
 481 \fBmq_timedsend\fP(2)   2.6.6
 482 \fBmq_unlink\fP(2)      2.6.6
 483 \fBmremap\fP(2) 2.0
 484 \fBmsgctl\fP(2) 2.0     See notes on \fBipc\fP(2)
 485 \fBmsgget\fP(2) 2.0     See notes on \fBipc\fP(2)
 486 \fBmsgrcv\fP(2) 2.0     See notes on \fBipc\fP(2)
 487 \fBmsgsnd\fP(2) 2.0     See notes on \fBipc\fP(2)
 488 \fBmsync\fP(2)  2.0
 489 .\" \fBmultiplexer\fP(2)        ??      __NR_multiplexer reserved on
 490 .\"             PowerPC, but unimplemented?
 491 \fBmunlock\fP(2)        2.0
 492 \fBmunlockall\fP(2)     2.0
 493 \fBmunmap\fP(2) 1.0
 494 \fBname_to_handle_at\fP(2)      2.6.39
 495 \fBnanosleep\fP(2)      2.0
 496 .\" 5590ff0d5528b60153c0b4e7b771472b5a95e297
 497 \fBnewfstatat\fP(2)     2.6.16  See \fBstat\fP(2)
 498 \fBnfsservctl\fP(2)     2.2     Removed in 3.1
 499 \fBnice\fP(2)   1.0
 500 \fBold_adjtimex\fP(2)   2.0     Alpha only; see NOTES
 501 \fBold_getrlimit\fP(2)  2.4     T{
 502 Old variant of \fBgetrlimit\fP(2)
 503 .br
 504 that used a different value
 505 .br
 506 for \fBRLIM_INFINITY\fP
 507 T}
 508 \fBoldfstat\fP(2)       1.0
 509 \fBoldlstat\fP(2)       1.0
 510 \fBoldolduname\fP(2)    1.0
 511 \fBoldstat\fP(2)        1.0
 512 \fBoldumount\fP(2)      2.4.116 T{
 513 Name of the old \fBumount\fP(2)
 514 .br
 515 syscall on Alpha
 516 T}
 517 \fBolduname\fP(2)       1.0
 518 \fBopen\fP(2)   1.0
 519 \fBopen_by_handle_at\fP(2)      2.6.39
 520 \fBopen_tree\fP(2)      5.2
 521 \fBopenat\fP(2) 2.6.16
 522 \fBopenat2\fP(2)        5.6
 523 .\" 9d02a4283e9ce4e9ca11ff00615bdacdb0515a1a
 524 \fBor1k_atomic\fP(2)    3.1     OpenRISC 1000 only
 525 \fBpause\fP(2)  1.0
 526 \fBpciconfig_iobase\fP(2)       2.2.15; 2.4     Not on x86
 527 .\" Alpha, PowerPC, ARM; not x86
 528 \fBpciconfig_read\fP(2) 2.0.26; 2.2     Not on x86
 529 .\" , PowerPC, ARM; not x86
 530 \fBpciconfig_write\fP(2)        2.0.26; 2.2     Not on x86
 531 .\" , PowerPC, ARM; not x86
 532 \fBperf_event_open\fP(2)        2.6.31  T{
 533 Was perf_counter_open() in
 534 .br
 535 2.6.31; renamed in 2.6.32
 536 T}
 537 \fBpersonality\fP(2)    1.2
 538 \fBperfctr\fP(2)        2.2     SPARC only; removed in 2.6.34
 539 .\"     commit c7d5a0050773e98d1094eaa9f2a1a793fafac300 removed perfctr()
 540 \fBperfmonctl\fP(2)     2.4     IA-64 only
 541 \fBpidfd_getfd\fP(2)    5.6
 542 \fBpidfd_send_signal\fP(2)      5.1
 543 \fBpidfd_open\fP(2)     5.3
 544 \fBpipe\fP(2)   1.0
 545 \fBpipe2\fP(2)  2.6.27
 546 \fBpivot_root\fP(2)     2.4
 547 \fBpkey_alloc\fP(2)     4.8
 548 \fBpkey_free\fP(2)      4.8
 549 \fBpkey_mprotect\fP(2)  4.8
 550 \fBpoll\fP(2)   2.0.36; 2.2
 551 \fBppoll\fP(2)  2.6.16
 552 \fBprctl\fP(2)  2.2
 553 \fBpread\fP(2)          T{
 554 Used for \fBpread64\fP(2) on AVR32
 555 .br
 556 (port removed in Linux 4.12)
 557 .br
 558 and Blackfin (port removed
 559 .br
 560 in Linux 4.17)
 561 T}
 562 \fBpread64\fP(2)                T{
 563 Added as "pread" in 2.2;
 564 .br
 565 renamed "pread64" in 2.6
 566 T}
 567 \fBpreadv\fP(2) 2.6.30
 568 \fBpreadv2\fP(2)        4.6
 569 \fBprlimit64\fP(2)      2.6.36
 570 \fBprocess_vm_readv\fP(2)       3.2
 571 \fBprocess_vm_writev\fP(2)      3.2
 572 \fBpselect6\fP(2)       2.6.16
 573 .\" Implements \fBpselect\fP(2)
 574 \fBptrace\fP(2) 1.0
 575 \fBpwrite\fP(2)         T{
 576 Used for \fBpwrite64\fP(2)
 577 .br
 578 on AVR32
 579 (port removed
 580 .br
 581 in Linux 4.12)
 582 and Blackfin
 583 .br
 584 (port removed in Linux 4.17)
 585 T}
 586 \fBpwrite64\fP(2)               T{
 587 Added as "pwrite" in 2.2;
 588 .br
 589 renamed "pwrite64" in 2.6
 590 T}
 591 \fBpwritev\fP(2)        2.6.30
 592 \fBpwritev2\fP(2)       4.6
 593 \fBquery_module\fP(2)   2.2     Removed in 2.6
 594 \fBquotactl\fP(2)       1.0
 595 \fBread\fP(2)   1.0
 596 \fBreadahead\fP(2)      2.4.13
 597 \fBreaddir\fP(2)        1.0
 598 .\" Supersedes \fBgetdents\fP(2)
 599 \fBreadlink\fP(2)       1.0
 600 \fBreadlinkat\fP(2)     2.6.16
 601 \fBreadv\fP(2)  2.0
 602 \fBreboot\fP(2) 1.0
 603 \fBrecv\fP(2)   2.0     See notes on \fBsocketcall\fP(2)
 604 \fBrecvfrom\fP(2)       2.0     See notes on \fBsocketcall\fP(2)
 605 \fBrecvmsg\fP(2)        2.0     See notes on \fBsocketcall\fP(2)
 606 \fBrecvmmsg\fP(2)       2.6.33
 607 \fBremap_file_pages\fP(2)       2.6     Deprecated since 3.16
 608 \fBremovexattr\fP(2)    2.6; 2.4.18
 609 \fBrename\fP(2) 1.0
 610 \fBrenameat\fP(2)       2.6.16
 611 \fBrenameat2\fP(2)      3.15
 612 \fBrequest_key\fP(2)    2.6.10
 613 \fBrestart_syscall\fP(2)        2.6
 614 .\" 921ebd8f2c081b3cf6c3b29ef4103eef3ff26054
 615 \fBriscv_flush_icache\fP(2)     4.15    RISC-V only
 616 \fBrmdir\fP(2)  1.0
 617 \fBrseq\fP(2)   4.18
 618 \fBrt_sigaction\fP(2)   2.2
 619 \fBrt_sigpending\fP(2)  2.2
 620 \fBrt_sigprocmask\fP(2) 2.2
 621 \fBrt_sigqueueinfo\fP(2)        2.2
 622 \fBrt_sigreturn\fP(2)   2.2
 623 \fBrt_sigsuspend\fP(2)  2.2
 624 \fBrt_sigtimedwait\fP(2)        2.2
 625 \fBrt_tgsigqueueinfo\fP(2)      2.6.31
 626 \fBrtas\fP(2)   2.6.2   PowerPC/PowerPC64 only
 627 \fBs390_runtime_instr\fP(2)     3.7     s390 only
 628 \fBs390_pci_mmio_read\fP(2)     3.19    s390 only
 629 \fBs390_pci_mmio_write\fP(2)    3.19    s390 only
 630 \fBs390_sthyi\fP(2)     4.15    s390 only
 631 \fBs390_guarded_storage\fP(2)   4.12    s390 only
 632 \fBsched_get_affinity\fP(2)     2.6     T{
 633 Name of \fBsched_getaffinity\fP(2)
 634 .br
 635 on SPARC and SPARC64
 636 T}
 637 \fBsched_get_priority_max\fP(2) 2.0
 638 \fBsched_get_priority_min\fP(2) 2.0
 639 \fBsched_getaffinity\fP(2)      2.6
 640 \fBsched_getattr\fP(2)  3.14
 641 \fBsched_getparam\fP(2) 2.0
 642 \fBsched_getscheduler\fP(2)     2.0
 643 \fBsched_rr_get_interval\fP(2)  2.0
 644 \fBsched_set_affinity\fP(2)     2.6     T{
 645 Name of \fBsched_setaffinity\fP(2)
 646 .br
 647 on SPARC and SPARC64
 648 T}
 649 \fBsched_setaffinity\fP(2)      2.6
 650 \fBsched_setattr\fP(2)  3.14
 651 \fBsched_setparam\fP(2) 2.0
 652 \fBsched_setscheduler\fP(2)     2.0
 653 \fBsched_yield\fP(2)    2.0
 654 \fBseccomp\fP(2)        3.17
 655 \fBselect\fP(2) 1.0
 656 \fBsemctl\fP(2) 2.0     See notes on \fBipc\fP(2)
 657 \fBsemget\fP(2) 2.0     See notes on \fBipc\fP(2)
 658 \fBsemop\fP(2)  2.0     See notes on \fBipc\fP(2)
 659 \fBsemtimedop\fP(2)     2.6; 2.4.22
 660 \fBsend\fP(2)   2.0     See notes on \fBsocketcall\fP(2)
 661 \fBsendfile\fP(2)       2.2
 662 \fBsendfile64\fP(2)     2.6; 2.4.19
 663 \fBsendmmsg\fP(2)       3.0
 664 \fBsendmsg\fP(2)        2.0     See notes on \fBsocketcall\fP(2)
 665 \fBsendto\fP(2) 2.0     See notes on \fBsocketcall\fP(2)
 666 \fBset_mempolicy\fP(2)  2.6.6
 667 \fBset_robust_list\fP(2)        2.6.17
 668 \fBset_thread_area\fP(2)        2.6
 669 \fBset_tid_address\fP(2)        2.6
 670 \fBset_tls\fP(2)        2.6.11  T{
 671 ARM OABI/EABI only (constant
 672 .br
 673 has \fB__ARM_NR\fP prefix)
 674 T}
 675 .\" \fBsetaltroot\fP(2) 2.6.10  T{
 676 .\" Removed in 2.6.11, exposed one
 677 .\" of implementation details of
 678 .\" \fBpersonality\fP(2) (creating an
 679 .\" alternative root, precursor of
 680 .\" mount namespaces) to user space.
 681 .\" T}
 682 .\" See http://lkml.org/lkml/2005/8/1/83
 683 .\" "[PATCH] remove sys_set_zone_reclaim()"
 684 \fBsetdomainname\fP(2)  1.0
 685 \fBsetfsgid\fP(2)       1.2
 686 \fBsetfsgid32\fP(2)     2.4
 687 \fBsetfsuid\fP(2)       1.2
 688 \fBsetfsuid32\fP(2)     2.4
 689 \fBsetgid\fP(2) 1.0
 690 \fBsetgid32\fP(2)       2.4
 691 \fBsetgroups\fP(2)      1.0
 692 \fBsetgroups32\fP(2)    2.4
 693 .\" arch/alpha/include/asm/core_lca.h
 694 \fBsethae\fP(2) 2.0     Alpha only; see NOTES
 695 \fBsethostname\fP(2)    1.0
 696 \fBsetitimer\fP(2)      1.0
 697 \fBsetns\fP(2)  3.0
 698 \fBsetpgid\fP(2)        1.0
 699 \fBsetpgrp\fP(2)        2.0     T{
 700 Alternative name for
 701 .br
 702 \fBsetpgid\fP(2) on Alpha
 703 T}
 704 \fBsetpriority\fP(2)    1.0
 705 \fBsetregid\fP(2)       1.0
 706 \fBsetregid32\fP(2)     2.4
 707 \fBsetresgid\fP(2)      2.2
 708 \fBsetresgid32\fP(2)    2.4
 709 \fBsetresuid\fP(2)      2.2
 710 \fBsetresuid32\fP(2)    2.4
 711 \fBsetreuid\fP(2)       1.0
 712 \fBsetreuid32\fP(2)     2.4
 713 \fBsetrlimit\fP(2)      1.0
 714 \fBsetsid\fP(2) 1.0
 715 \fBsetsockopt\fP(2)     2.0     See notes on \fBsocketcall\fP(2)
 716 \fBsettimeofday\fP(2)   1.0
 717 \fBsetuid\fP(2) 1.0
 718 \fBsetuid32\fP(2)       2.4
 719 \fBsetup\fP(2)  1.0     Removed in 2.2
 720 \fBsetxattr\fP(2)       2.6; 2.4.18
 721 \fBsgetmask\fP(2)       1.0
 722 \fBshmat\fP(2)  2.0     See notes on \fBipc\fP(2)
 723 \fBshmctl\fP(2) 2.0     See notes on \fBipc\fP(2)
 724 \fBshmdt\fP(2)  2.0     See notes on \fBipc\fP(2)
 725 \fBshmget\fP(2) 2.0     See notes on \fBipc\fP(2)
 726 \fBshutdown\fP(2)       2.0     See notes on \fBsocketcall\fP(2)
 727 \fBsigaction\fP(2)      1.0
 728 \fBsigaltstack\fP(2)    2.2
 729 \fBsignal\fP(2) 1.0
 730 \fBsignalfd\fP(2)       2.6.22
 731 \fBsignalfd4\fP(2)      2.6.27
 732 \fBsigpending\fP(2)     1.0
 733 \fBsigprocmask\fP(2)    1.0
 734 \fBsigreturn\fP(2)      1.0
 735 \fBsigsuspend\fP(2)     1.0
 736 \fBsocket\fP(2) 2.0     See notes on \fBsocketcall\fP(2)
 737 \fBsocketcall\fP(2)     1.0
 738 .\" Implements BSD socket calls
 739 \fBsocketpair\fP(2)     2.0     See notes on \fBsocketcall\fP(2)
 740 .\" 5a0015d62668e64c8b6e02e360fbbea121bfd5e6
 741 \fBspill\fP(2)  2.6.13  Xtensa only
 742 \fBsplice\fP(2) 2.6.17
 743 \fBspu_create\fP(2)     2.6.16  PowerPC/PowerPC64 only
 744 \fBspu_run\fP(2)        2.6.16  PowerPC/PowerPC64 only
 745 \fBsram_alloc\fP(2)     2.6.22  T{
 746 Blackfin (port removed
 747 .br
 748 in Linux 4.17)
 749 T}
 750 \fBsram_free\fP(2)      2.6.22  T{
 751 Blackfin (port removed
 752 .br
 753 in Linux 4.17)
 754 T}
 755 \fBssetmask\fP(2)       1.0
 756 \fBstat\fP(2)   1.0
 757 \fBstat64\fP(2) 2.4
 758 \fBstatfs\fP(2) 1.0
 759 \fBstatfs64\fP(2)       2.6
 760 \fBstatx\fP(2)  4.11
 761 \fBstime\fP(2)  1.0
 762 \fBsubpage_prot\fP(2)   2.6.25  PowerPC/PowerPC64 only
 763 \fBswapcontext\fP(2)    2.6.3   PowerPC/PowerPC64 only
 764 .\" 529d235a0e190ded1d21ccc80a73e625ebcad09b
 765 \fBswitch_endian\fP(2)  4.1     PowerPC64 only
 766 \fBswapcontext\fP(2)    2.6.3   PowerPC only
 767 \fBswapoff\fP(2)        1.0
 768 \fBswapon\fP(2) 1.0
 769 \fBsymlink\fP(2)        1.0
 770 \fBsymlinkat\fP(2)      2.6.16
 771 \fBsync\fP(2)   1.0
 772 \fBsync_file_range\fP(2)        2.6.17
 773 \fBsync_file_range2\fP(2)       2.6.22
 774 .\" PowerPC, ARM, tile
 775 .\" First appeared on ARM, as arm_sync_file_range(), but later renamed
 776 .\" \fBsys_debug_setcontext\fP(2)       ???     PowerPC if CONFIG_PPC32
 777 \fBsyncfs\fP(2) 2.6.39
 778 \fBsys_debug_setcontext\fP(2)   2.6.11  PowerPC only
 779 \fBsyscall\fP(2)        1.0     T{
 780 Still available on ARM OABI
 781 .br
 782 and MIPS O32 ABI
 783 T}
 784 \fBsysfs\fP(2)  1.2
 785 \fBsysinfo\fP(2)        1.0
 786 \fBsyslog\fP(2) 1.0
 787 .\" glibc interface is \fBklogctl\fP(3)
 788 \fBsysmips\fP(2)        2.6.0   MIPS only
 789 \fBtee\fP(2)    2.6.17
 790 \fBtgkill\fP(2) 2.6
 791 \fBtime\fP(2)   1.0
 792 \fBtimer_create\fP(2)   2.6
 793 \fBtimer_delete\fP(2)   2.6
 794 \fBtimer_getoverrun\fP(2)       2.6
 795 \fBtimer_gettime\fP(2)  2.6
 796 \fBtimer_settime\fP(2)  2.6
 797 .\" .\" b215e283992899650c4271e7385c79e26fb9a88e
 798 .\" .\" 4d672e7ac79b5ec5cdc90e450823441e20464691
 799 .\" \fBtimerfd\fP(2)    2.6.22  T{
 800 .\" Old timerfd interface,
 801 .\" removed in 2.6.25
 802 .\" T}
 803 \fBtimerfd_create\fP(2) 2.6.25
 804 \fBtimerfd_gettime\fP(2)        2.6.25
 805 \fBtimerfd_settime\fP(2)        2.6.25
 806 \fBtimes\fP(2)  1.0
 807 \fBtkill\fP(2)  2.6; 2.4.22
 808 \fBtruncate\fP(2)       1.0
 809 \fBtruncate64\fP(2)     2.4
 810 \fBugetrlimit\fP(2)     2.4
 811 \fBumask\fP(2)  1.0
 812 \fBumount\fP(2) 1.0
 813 .\" sys_oldumount() -- __NR_umount
 814 \fBumount2\fP(2)        2.2
 815 .\" sys_umount() -- __NR_umount2
 816 \fBuname\fP(2)  1.0
 817 \fBunlink\fP(2) 1.0
 818 \fBunlinkat\fP(2)       2.6.16
 819 \fBunshare\fP(2)        2.6.16
 820 \fBuselib\fP(2) 1.0
 821 \fBustat\fP(2)  1.0
 822 \fBuserfaultfd\fP(2)    4.3
 823 \fBusr26\fP(2)  2.4.8.1 ARM OABI only
 824 \fBusr32\fP(2)  2.4.8.1 ARM OABI only
 825 \fButime\fP(2)  1.0
 826 \fButimensat\fP(2)      2.6.22
 827 \fButimes\fP(2) 2.2
 828 \fButrap_install\fP(2)  2.2     SPARC64 only
 829 .\" FIXME . document utrap_install()
 830 .\" There's a man page for Solaris 5.11
 831 \fBvfork\fP(2)  2.2
 832 \fBvhangup\fP(2)        1.0
 833 \fBvm86old\fP(2)        1.0     T{
 834 Was "vm86"; renamed in
 835 .br
 836 2.0.28/2.2
 837 T}
 838 \fBvm86\fP(2)   2.0.28; 2.2
 839 \fBvmsplice\fP(2)       2.6.17
 840 \fBwait4\fP(2)  1.0
 841 \fBwaitid\fP(2) 2.6.10
 842 \fBwaitpid\fP(2)        1.0
 843 \fBwrite\fP(2)  1.0
 844 \fBwritev\fP(2) 2.0
 845 .\" 5a0015d62668e64c8b6e02e360fbbea121bfd5e6
 846 \fBxtensa\fP(2) 2.6.13  Xtensa only
 847 .TE
 848 .ad
 849 .PP
 850 On many platforms, including x86-32, socket calls are all multiplexed
 851 (via glibc wrapper functions) through
 852 .BR socketcall (2)
 853 and similarly System\ V IPC calls are multiplexed through
 854 .BR ipc (2).
 855 .PP
 856 Although slots are reserved for them in the system call table,
 857 the following system calls are not implemented in the standard kernel:
 858 .BR afs_syscall (2), \" __NR_afs_syscall is 53 on Linux 2.6.22/i386
 859 .BR break (2),       \" __NR_break is 17 on Linux 2.6.22/i386
 860 .BR ftime (2),       \" __NR_ftime is 35 on Linux 2.6.22/i386
 861 .BR getpmsg (2),     \" __NR_getpmsg is 188 on Linux 2.6.22/i386
 862 .BR gtty (2),        \" __NR_gtty is 32 on Linux 2.6.22/i386
 863 .BR idle (2),        \" __NR_idle is 112 on Linux 2.6.22/i386
 864 .BR lock (2),        \" __NR_lock is 53 on Linux 2.6.22/i386
 865 .BR madvise1 (2),    \" __NR_madvise1 is 219 on Linux 2.6.22/i386
 866 .BR mpx (2),         \" __NR_mpx is 66 on Linux 2.6.22/i386
 867 .BR phys (2),        \" Slot has been reused
 868 .BR prof (2),        \" __NR_prof is 44 on Linux 2.6.22/i386
 869 .BR profil (2),      \" __NR_profil is 98 on Linux 2.6.22/i386
 870 .BR putpmsg (2),     \" __NR_putpmsg is 189 on Linux 2.6.22/i386
 871 .\" __NR_security is 223 on Linux 2.4/i386; absent on 2.6/i386, present
 872 .\" on a couple of 2.6 architectures
 873 .BR security (2),    \" __NR_security is 223 on Linux 2.4/i386
 874 .\" The security call is for future use.
 875 .BR stty (2),        \" __NR_stty is 31 on Linux 2.6.22/i386
 876 .BR tuxcall (2),     \" __NR_tuxcall is 184 on x86_64, also on PPC and alpha
 877 .BR ulimit (2),      \" __NR_ulimit is 58 on Linux 2.6.22/i386
 878 and
 879 .BR vserver (2)      \" __NR_vserver is 273 on Linux 2.6.22/i386
 880 (see also
 881 .BR unimplemented (2)).
 882 However,
 883 .BR ftime (3),
 884 .BR profil (3),
 885 and
 886 .BR ulimit (3)
 887 exist as library routines.
 888 The slot for
 889 .BR phys (2)
 890 is in use since kernel 2.1.116 for
 891 .BR umount (2);
 892 .BR phys (2)
 893 will never be implemented.
 894 The
 895 .BR getpmsg (2)
 896 and
 897 .BR putpmsg (2)
 898 calls are for kernels patched to support STREAMS,
 899 and may never be in the standard kernel.
 900 .PP
 901 There was briefly
 902 .BR set_zone_reclaim (2),
 903 added in Linux 2.6.13, and removed in 2.6.16;
 904 this system call was never available to user space.
 905 .SH NOTES
 906 .PP
 907 Roughly speaking, the code belonging to the system call
 908 with number __NR_xxx defined in
 909 .I /usr/include/asm/unistd.h
 910 can be found in the Linux kernel source in the routine
 911 .IR sys_xxx ().
 912 There are many exceptions, however, mostly because
 913 older system calls were superseded by newer ones,
 914 and this has been treated somewhat unsystematically.
 915 On platforms with
 916 proprietary operating-system emulation,
 917 such as sparc, sparc64, and alpha,
 918 there are many additional system calls; mips64 also contains a full
 919 set of 32-bit system calls.
 920 .PP
 921 Over time, changes to the interfaces of some system calls have been
 922 necessary.
 923 One reason for such changes was the need to increase the size of
 924 structures or scalar values passed to the system call.
 925 Because of these changes, certain architectures
 926 (notably, longstanding 32-bit architectures such as i386)
 927 now have various groups of related system calls (e.g.,
 928 .BR truncate (2)
 929 and
 930 .BR truncate64 (2))
 931 which perform similar tasks, but which vary in
 932 details such as the size of their arguments.
 933 (As noted earlier, applications are generally unaware of this:
 934 the glibc wrapper functions do some work to ensure that the right
 935 system call is invoked, and that ABI compatibility is
 936 preserved for old binaries.)
 937 Examples of systems calls that exist in multiple versions are
 938 the following:
 939 .IP * 3
 940 By now there are three different versions of
 941 .BR stat (2):
 942 .IR sys_stat ()
 943 (slot
 944 .IR __NR_oldstat ),
 945 .IR sys_newstat ()
 946 (slot
 947 .IR __NR_stat ),
 948 and
 949 .IR sys_stat64 ()
 950 (slot
 951 .IR __NR_stat64 ),
 952 with the last being the most current.
 953 .\" e.g., on 2.6.22/i386: __NR_oldstat 18, __NR_stat 106, __NR_stat64 195
 954 .\" The stat system calls deal with three different data structures,
 955 .\" defined in include/asm-i386/stat.h: __old_kernel_stat, stat, stat64
 956 A similar story applies for
 957 .BR lstat (2)
 958 and
 959 .BR fstat (2).
 960 .IP *
 961 Similarly, the defines
 962 .IR __NR_oldolduname ,
 963 .IR __NR_olduname ,
 964 and
 965 .I __NR_uname
 966 refer to the routines
 967 .IR sys_olduname (),
 968 .IR sys_uname ()
 969 and
 970 .IR sys_newuname ().
 971 .IP *
 972 In Linux 2.0, a new version of
 973 .BR vm86 (2)
 974 appeared, with the old and the new kernel routines being named
 975 .IR sys_vm86old ()
 976 and
 977 .IR sys_vm86 ().
 978 .IP *
 979 In Linux 2.4, a new version of
 980 .BR getrlimit (2)
 981 appeared, with the old and the new kernel routines being named
 982 .IR sys_old_getrlimit ()
 983 (slot
 984 .IR __NR_getrlimit )
 985 and
 986 .IR sys_getrlimit ()
 987 (slot
 988 .IR __NR_ugetrlimit ).
 989 .IP *
 990 Linux 2.4 increased the size of user and group IDs from 16 to 32 bits.
 991 .\" 64-bit off_t changes: ftruncate64, *stat64,
 992 .\" fcntl64 (because of the flock structure), getdents64, *statfs64
 993 To support this change, a range of system calls were added
 994 (e.g.,
 995 .BR chown32 (2),
 996 .BR getuid32 (2),
 997 .BR getgroups32 (2),
 998 .BR setresuid32 (2)),
 999 superseding earlier calls of the same name without the
1000 "32" suffix.
1001 .IP *
1002 Linux 2.4 added support for applications on 32-bit architectures
1003 to access large files (i.e., files for which the sizes and
1004 file offsets can't be represented in 32 bits.)
1005 To support this change, replacements were required for system calls
1006 that deal with file offsets and sizes.
1007 Thus the following system calls were added:
1008 .BR fcntl64 (2),
1009 .BR getdents64 (2),
1010 .BR stat64 (2),
1011 .BR statfs64 (2),
1012 .BR truncate64 (2),
1013 and their analogs that work with file descriptors or
1014 symbolic links.
1015 These system calls supersede the older system calls
1016 which, except in the case of the "stat" calls,
1017 have the same name without the "64" suffix.
1018 .IP
1019 On newer platforms that only have 64-bit file access and 32-bit UIDs/GIDs
1020 (e.g., alpha, ia64, s390x, x86-64), there is just a single version of
1021 the UID/GID and file access system calls.
1022 On platforms (typically, 32-bit platforms) where the *64 and *32 calls exist,
1023 the other versions are obsolete.
1024 .IP *
1025 The
1026 .I rt_sig*
1027 calls were added in kernel 2.2 to support the addition
1028 of real-time signals (see
1029 .BR signal (7)).
1030 These system calls supersede the older system calls of the same
1031 name without the "rt_" prefix.
1032 .IP *
1033 The
1034 .BR select (2)
1035 and
1036 .BR mmap (2)
1037 system calls use five or more arguments,
1038 which caused problems in the way
1039 argument passing on the i386 used to be set up.
1040 Thus, while other architectures have
1041 .IR sys_select ()
1042 and
1043 .IR sys_mmap ()
1044 corresponding to
1045 .I __NR_select
1046 and
1047 .IR __NR_mmap ,
1048 on i386 one finds
1049 .IR old_select ()
1050 and
1051 .IR old_mmap ()
1052 (routines that use a pointer to an
1053 argument block) instead.
1054 These days passing five arguments
1055 is not a problem any more, and there is a
1056 .I __NR__newselect
1057 .\" (used by libc 6)
1058 that corresponds directly to
1059 .IR sys_select ()
1060 and similarly
1061 .IR __NR_mmap2 .
1062 s390x is the only 64-bit architecture that has
1063 .IR old_mmap ().
1064 .\" .PP
1065 .\" Two system call numbers,
1066 .\" .IR __NR__llseek
1067 .\" and
1068 .\" .IR __NR__sysctl
1069 .\" have an additional underscore absent in
1070 .\" .IR sys_llseek ()
1071 .\" and
1072 .\" .IR sys_sysctl ().
1073 .\"
1074 .\" In kernel 2.1.81,
1075 .\" .BR lchown (2)
1076 .\" and
1077 .\" .BR chown (2)
1078 .\" were swapped; that is,
1079 .\" .BR lchown (2)
1080 .\" was added with the semantics that were then current for
1081 .\" .BR chown (2),
1082 .\" and the semantics of the latter call were changed to what
1083 .\" they are today.
1084 .\"
1085 .\"
1086 .SS "Architecture-specific details: Alpha"
1087 .IP * 3
1088 .BR getxgid (2)
1089 returns a pair of GID and effective GID via registers
1090 \fBr0\fP and \fBr20\fP; it is provided
1091 instead of
1092 \fBgetgid\fP(2) and \fBgetegid\fP(2).
1093 .IP *
1094 .BR getxpid (2)
1095 returns a pair of PID and parent PID via registers
1096 \fBr0\fP and \fBr20\fP; it is provided instead of
1097 \fBgetpid\fP(2) and \fBgetppid\fP(2).
1098 .IP *
1099 .BR old_adjtimex (2)
1100 is a variant of \fBadjtimex\fP(2) that uses \fIstruct timeval32\fP,
1101 for compatibility with OSF/1.
1102 .IP *
1103 .BR getxuid (2)
1104 returns a pair of GID and effective GID via registers
1105 \fBr0\fP and \fBr20\fP; it is provided instead of
1106 \fBgetuid\fP(2) and \fBgeteuid\fP(2).
1107 .IP *
1108 .BR sethae (2)
1109 is used for configuring the Host Address Extension register on
1110 low-cost Alphas in order to access address space beyond first 27 bits.
1111 .SH SEE ALSO
1112 .BR intro (2),
1113 .BR syscall (2),
1114 .BR unimplemented (2),
1115 .BR errno (3),
1116 .BR libc (7),
1117 .BR vdso (7)