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SYSCALLS(2)		   Linux Programmer's Manual		   SYSCALLS(2)

       syscalls - Linux system calls

       Linux system calls.

       The system call is the fundamental interface between an application and
       the Linux kernel.

   System calls and library wrapper functions
       System calls are generally not invoked directly, but rather via wrapper
       functions  in  glibc  (or  perhaps some other library).	For details of
       direct invocation of a system  call,  see  intro(2).   Often,  but  not
       always, the name of the wrapper function is the same as the name of the
       system call that it invokes.  For example, glibc	 contains  a  function
       truncate() which invokes the underlying "truncate" system call.

       Often the glibc wrapper function is quite thin, doing little work other
       than copying arguments to the right registers before invoking the  sys-
       tem  call,  and	then setting errno appropriately after the system call
       has returned.   (These  are  the	 same  steps  that  are	 performed  by
       syscall(2), which can be used to invoke system calls for which no wrap-
       per function is provided.)  Note: system calls indicate	a  failure  by
       returning a negative error number to the caller; when this happens, the
       wrapper function negates the returned error number (to  make  it	 posi-
       tive), copies it to errno, and returns -1 to the caller of the wrapper.

       Sometimes,  however,  the  wrapper function does some extra work before
       invoking the system call.  For example, nowadays there are (for reasons
       described  below)  two  related	system	calls,	truncate(2)  and trun-
       cate64(2), and the glibc truncate() wrapper function  checks  which  of
       those  system  calls  are  provided  by the kernel and determines which
       should be employed.

   System call list
       Below is a list of the Linux system calls.  In  the  list,  the	Kernel
       column  indicates  the  kernel version for those system calls that were
       new in Linux 2.2, or have appeared since that kernel version.  Note the
       following points:

       *  Where	 no  kernel  version is indicated, the system call appeared in
	  kernel 1.0 or earlier.

       *  Where a system call is marked "1.2" this means the system call prob-
	  ably	appeared  in  a	 1.1.x kernel version, and first appeared in a
	  stable kernel with 1.2.  (Development of the 1.2 kernel  was	initi-
	  ated	from  a	 branch	 of kernel 1.0.6 via the 1.1.x unstable kernel

       *  Where a system call is marked "2.0" this means the system call prob-
	  ably	appeared  in  a	 1.3.x kernel version, and first appeared in a
	  stable kernel with 2.0.  (Development of the 2.0 kernel  was	initi-
	  ated from a branch of kernel 1.2.x, somewhere around 1.2.10, via the
	  1.3.x unstable kernel series.)

       *  Where a system call is marked "2.2" this means the system call prob-
	  ably	appeared  in  a	 2.1.x kernel version, and first appeared in a
	  stable kernel with 2.2.0.  (Development of the 2.2 kernel was initi-
	  ated	from  a	 branch of kernel 2.0.21 via the 2.1.x unstable kernel

       *  Where a system call is marked "2.4" this means the system call prob-
	  ably	appeared  in  a	 2.3.x kernel version, and first appeared in a
	  stable kernel with 2.4.0.  (Development of the 2.4 kernel was initi-
	  ated	from  a	 branch	 of kernel 2.2.8 via the 2.3.x unstable kernel

       *  Where a system call is marked "2.6" this means the system call prob-
	  ably	appeared  in  a	 2.5.x kernel version, and first appeared in a
	  stable kernel with 2.6.0.  (Development of kernel 2.6 was  initiated
	  from	a  branch  of  kernel  2.4.15  via  the	 2.5.x unstable kernel

       *  Starting with kernel 2.6.0, the development model changed,  and  new
	  system  calls	 may  appear in each 2.6.x release.  In this case, the
	  exact version number where the system call appeared is shown.	  This
	  convention  continues	 with the 3.x kernel series, which followed on
	  from kernel 2.6.39, and the 4.x kernel  series,  which  followed  on
	  from kernel 3.19.

       *  In  some  cases,  a  system call was added to a stable kernel series
	  after it branched from the previous stable kernel series,  and  then
	  backported  into the earlier stable kernel series.  For example some
	  system calls that appeared in 2.6.x  were  also  backported  into  a
	  2.4.x	 release after 2.4.15.	When this is so, the version where the
	  system call appeared in both of the major kernel series is listed.

       The list of system calls that are available as at kernel 4.9 (or	 in  a
       few cases only on older kernels) is as follows:

       System call		  Kernel	Notes

       _llseek(2)		  1.2
       _newselect(2)		  2.0
       _sysctl(2)		  2.0
       accept(2)		  2.0		See notes on socketcall(2)
       accept4(2)		  2.6.28
       access(2)		  1.0
       acct(2)			  1.0
       add_key(2)		  2.6.10
       adjtimex(2)		  1.0
       alarm(2)			  1.0
       alloc_hugepages(2)	  2.5.36	Removed in 2.5.44
       bdflush(2)		  1.2		Deprecated (does nothing)
						since 2.6
       bind(2)			  2.0		See notes on socketcall(2)
       bpf(2)			  3.18
       brk(2)			  1.0
       cacheflush(2)		  1.2		Not on x86
       capget(2)		  2.2
       capset(2)		  2.2
       chdir(2)			  1.0
       chmod(2)			  1.0
       chown(2)			  2.2		See chown(2) for
						version details
       chown32(2)		  2.4
       chroot(2)		  1.0
       clock_adjtime(2)		  2.6.39
       clock_getres(2)		  2.6
       clock_gettime(2)		  2.6
       clock_nanosleep(2)	  2.6
       clock_settime(2)		  2.6
       clone(2)			  1.0
       close(2)			  1.0
       connect(2)		  2.0		See notes on socketcall(2)

       copy_file_range(2)	  4.5
       creat(2)			  1.0
       create_module(2)		  1.0		Removed in 2.6
       delete_module(2)		  1.0
       dup(2)			  1.0
       dup2(2)			  1.0
       dup3(2)			  2.6.27
       epoll_create(2)		  2.6
       epoll_create1(2)		  2.6.27
       epoll_ctl(2)		  2.6
       epoll_pwait(2)		  2.6.19
       epoll_wait(2)		  2.6
       eventfd(2)		  2.6.22
       eventfd2(2)		  2.6.27
       execve(2)		  1.0
       execveat(2)		  3.19
       exit(2)			  1.0
       exit_group(2)		  2.6
       faccessat(2)		  2.6.16
       fadvise64(2)		  2.6
       fadvise64_64(2)		  2.6
       fallocate(2)		  2.6.23
       fanotify_init(2)		  2.6.37
       fanotify_mark(2)		  2.6.37
       fchdir(2)		  1.0
       fchmod(2)		  1.0
       fchmodat(2)		  2.6.16
       fchown(2)		  1.0
       fchown32(2)		  2.4
       fchownat(2)		  2.6.16
       fcntl(2)			  1.0
       fcntl64(2)		  2.4
       fdatasync(2)		  2.0
       fgetxattr(2)		  2.6; 2.4.18
       finit_module(2)		  3.8
       flistxattr(2)		  2.6; 2.4.18
       flock(2)			  2.0
       fork(2)			  1.0
       free_hugepages(2)	  2.5.36	Removed in 2.5.44
       fremovexattr(2)		  2.6; 2.4.18
       fsetxattr(2)		  2.6; 2.4.18
       fstat(2)			  1.0
       fstat64(2)		  2.4
       fstatat64(2)		  2.6.16
       fstatfs(2)		  1.0
       fstatfs64(2)		  2.6
       fsync(2)			  1.0
       ftruncate(2)		  1.0
       ftruncate64(2)		  2.4
       futex(2)			  2.6
       futimesat(2)		  2.6.16
       get_kernel_syms(2)	  1.0		Removed in 2.6
       get_mempolicy(2)		  2.6.6
       get_robust_list(2)	  2.6.17
       get_thread_area(2)	  2.6
       getcpu(2)		  2.6.19
       getcwd(2)		  2.2
       getdents(2)		  2.0
       getdents64(2)		  2.4
       getegid(2)		  1.0
       getegid32(2)		  2.4
       geteuid(2)		  1.0
       geteuid32(2)		  2.4
       getgid(2)		  1.0
       getgid32(2)		  2.4

       getgroups(2)		  1.0
       getgroups32(2)		  2.4
       getitimer(2)		  1.0
       getpeername(2)		  2.0		See notes on socketcall(2)
       getpagesize(2)		  2.0		Not on x86
       getpgid(2)		  1.0
       getpgrp(2)		  1.0
       getpid(2)		  1.0
       getppid(2)		  1.0
       getpriority(2)		  1.0
       getrandom(2)		  3.17
       getresgid(2)		  2.2
       getresgid32(2)		  2.4
       getresuid(2)		  2.2
       getresuid32(2)		  2.4
       getrlimit(2)		  1.0
       getrusage(2)		  1.0
       getsid(2)		  2.0
       getsockname(2)		  2.0		See notes on socketcall(2)
       getsockopt(2)		  2.0		See notes on socketcall(2)
       gettid(2)		  2.4.11
       gettimeofday(2)		  1.0
       getuid(2)		  1.0
       getuid32(2)		  2.4
       getxattr(2)		  2.6; 2.4.18
       init_module(2)		  1.0
       inotify_add_watch(2)	  2.6.13
       inotify_init(2)		  2.6.13
       inotify_init1(2)		  2.6.27
       inotify_rm_watch(2)	  2.6.13
       io_cancel(2)		  2.6
       io_destroy(2)		  2.6
       io_getevents(2)		  2.6
       io_setup(2)		  2.6
       io_submit(2)		  2.6
       ioctl(2)			  1.0
       ioperm(2)		  1.0
       iopl(2)			  1.0
       ioprio_get(2)		  2.6.13
       ioprio_set(2)		  2.6.13
       ipc(2)			  1.0
       kcmp(2)			  3.5
       kern_features(2)		  3.7		Sparc64
       kexec_file_load(2)	  3.17
       kexec_load(2)		  2.6.13
       keyctl(2)		  2.6.10
       kill(2)			  1.0
       lchown(2)		  1.0		See chown(2) for
						version details
       lchown32(2)		  2.4
       lgetxattr(2)		  2.6; 2.4.18
       link(2)			  1.0
       linkat(2)		  2.6.16
       listen(2)		  2.0		See notes on socketcall(2)
       listxattr(2)		  2.6; 2.4.18
       llistxattr(2)		  2.6; 2.4.18
       lookup_dcookie(2)	  2.6
       lremovexattr(2)		  2.6; 2.4.18
       lseek(2)			  1.0
       lsetxattr(2)		  2.6; 2.4.18
       lstat(2)			  1.0
       lstat64(2)		  2.4
       madvise(2)		  2.4
       mbind(2)			  2.6.6
       memfd_create(2)		  3.17

       migrate_pages(2)		  2.6.16
       mincore(2)		  2.4
       mkdir(2)			  1.0
       mkdirat(2)		  2.6.16
       mknod(2)			  1.0
       mknodat(2)		  2.6.16
       mlock(2)			  2.0
       mlock2(2)		  4.4
       mlockall(2)		  2.0
       mmap(2)			  1.0
       mmap2(2)			  2.4
       modify_ldt(2)		  1.0
       mount(2)			  1.0
       move_pages(2)		  2.6.18
       mprotect(2)		  1.0
       mq_getsetattr(2)		  2.6.6
       mq_notify(2)		  2.6.6
       mq_open(2)		  2.6.6
       mq_timedreceive(2)	  2.6.6
       mq_timedsend(2)		  2.6.6
       mq_unlink(2)		  2.6.6
       mremap(2)		  2.0
       msgctl(2)		  2.0		See notes on ipc(2)
       msgget(2)		  2.0		See notes on ipc(2)
       msgrcv(2)		  2.0		See notes on ipc(2)
       msgsnd(2)		  2.0		See notes on ipc(2)
       msync(2)			  2.0
       munlock(2)		  2.0
       munlockall(2)		  2.0
       munmap(2)		  1.0
       name_to_handle_at(2)	  2.6.39
       nanosleep(2)		  2.0
       nfsservctl(2)		  2.2		Removed in 3.1
       nice(2)			  1.0
       oldfstat(2)		  1.0
       oldlstat(2)		  1.0
       oldolduname(2)		  1.0
       oldstat(2)		  1.0
       olduname(2)		  1.0
       open(2)			  1.0
       open_by_handle_at(2)	  2.6.39
       openat(2)		  2.6.16
       pause(2)			  1.0
       pciconfig_iobase(2)	  2.2.15; 2.4	Not on x86
       pciconfig_read(2)	  2.0.26; 2.2	Not on x86
       pciconfig_write(2)	  2.0.26; 2.2	Not on x86
       perf_event_open(2)	  2.6.31	Was perf_counter_open() in
						2.6.31; renamed in 2.6.32
       personality(2)		  1.2
       perfctr(2)		  2.2		Sparc; removed in 2.6.34
       perfmonctl(2)		  2.4		ia64
       pipe(2)			  1.0
       pipe2(2)			  2.6.27
       pivot_root(2)		  2.4
       pkey_alloc(2)		  4.8
       pkey_free(2)		  4.8
       pkey_mprotect(2)		  4.8
       poll(2)			  2.0.36; 2.2
       ppc_rtas(2)		  2.6.2		PowerPC only
       ppc_swapcontext(2)	  2.6.3		PowerPC only
       ppoll(2)			  2.6.16
       prctl(2)			  2.2
       pread64(2)				Added as "pread" in 2.2;
						renamed "pread64" in 2.6
       preadv(2)		  2.6.30

       preadv2(2)		  4.6
       prlimit64(2)		  2.6.36
       process_vm_readv(2)	  3.2
       process_vm_writev(2)	  3.2
       pselect6(2)		  2.6.16
       ptrace(2)		  1.0
       pwrite64(2)				Added as "pwrite" in 2.2;
						renamed "pwrite64" in 2.6
       pwritev(2)		  2.6.30
       pwritev2(2)		  4.6
       query_module(2)		  2.2		Removed in 2.6
       quotactl(2)		  1.0
       read(2)			  1.0
       readahead(2)		  2.4.13
       readdir(2)		  1.0
       readlink(2)		  1.0
       readlinkat(2)		  2.6.16
       readv(2)			  2.0
       reboot(2)		  1.0
       recv(2)			  2.0		See notes on socketcall(2)
       recvfrom(2)		  2.0		See notes on socketcall(2)
       recvmsg(2)		  2.0		See notes on socketcall(2)
       recvmmsg(2)		  2.6.33
       remap_file_pages(2)	  2.6		Deprecated since 3.16
       removexattr(2)		  2.6; 2.4.18
       rename(2)		  1.0
       renameat(2)		  2.6.16
       renameat2(2)		  3.15
       request_key(2)		  2.6.10
       restart_syscall(2)	  2.6
       rmdir(2)			  1.0
       rt_sigaction(2)		  2.2
       rt_sigpending(2)		  2.2
       rt_sigprocmask(2)	  2.2
       rt_sigqueueinfo(2)	  2.2
       rt_sigreturn(2)		  2.2
       rt_sigsuspend(2)		  2.2
       rt_sigtimedwait(2)	  2.2
       rt_tgsigqueueinfo(2)	  2.6.31
       s390_runtime_instr(2)	  3.7		s390 only
       s390_pci_mmio_read(2)	  3.19		s390 only
       s390_pci_mmio_write(2)	  3.19		s390 only
       sched_get_priority_max(2)  2.0
       sched_get_priority_min(2)  2.0
       sched_getaffinity(2)	  2.6
       sched_getattr(2)		  3.14
       sched_getparam(2)	  2.0
       sched_getscheduler(2)	  2.0
       sched_rr_get_interval(2)	  2.0
       sched_setaffinity(2)	  2.6
       sched_setattr(2)		  3.14
       sched_setparam(2)	  2.0
       sched_setscheduler(2)	  2.0
       sched_yield(2)		  2.0
       seccomp(2)		  3.17
       select(2)		  1.0
       semctl(2)		  2.0		See notes on ipc(2)
       semget(2)		  2.0		See notes on ipc(2)
       semop(2)			  2.0		See notes on ipc(2)
       semtimedop(2)		  2.6; 2.4.22
       send(2)			  2.0		See notes on socketcall(2)
       sendfile(2)		  2.2
       sendfile64(2)		  2.6; 2.4.19
       sendmmsg(2)		  3.0
       sendmsg(2)		  2.0		See notes on socketcall(2)

       sendto(2)		  2.0		See notes on socketcall(2)
       set_mempolicy(2)		  2.6.6
       set_robust_list(2)	  2.6.17
       set_thread_area(2)	  2.6
       set_tid_address(2)	  2.6
       setdomainname(2)		  1.0
       setfsgid(2)		  1.2
       setfsgid32(2)		  2.4
       setfsuid(2)		  1.2
       setfsuid32(2)		  2.4
       setgid(2)		  1.0
       setgid32(2)		  2.4
       setgroups(2)		  1.0
       setgroups32(2)		  2.4
       sethostname(2)		  1.0
       setitimer(2)		  1.0
       setns(2)			  3.0
       setpgid(2)		  1.0
       setpriority(2)		  1.0
       setregid(2)		  1.0
       setregid32(2)		  2.4
       setresgid(2)		  2.2
       setresgid32(2)		  2.4
       setresuid(2)		  2.2
       setresuid32(2)		  2.4
       setreuid(2)		  1.0
       setreuid32(2)		  2.4
       setrlimit(2)		  1.0
       setsid(2)		  1.0
       setsockopt(2)		  2.0		See notes on socketcall(2)
       settimeofday(2)		  1.0
       setuid(2)		  1.0
       setuid32(2)		  2.4
       setup(2)			  1.0		Removed in 2.2
       setxattr(2)		  2.6; 2.4.18
       sgetmask(2)		  1.0
       shmat(2)			  2.0		See notes on ipc(2)
       shmctl(2)		  2.0		See notes on ipc(2)
       shmdt(2)			  2.0		See notes on ipc(2)
       shmget(2)		  2.0		See notes on ipc(2)
       shutdown(2)		  2.0		See notes on socketcall(2)
       sigaction(2)		  1.0
       sigaltstack(2)		  2.2
       signal(2)		  1.0
       signalfd(2)		  2.6.22
       signalfd4(2)		  2.6.27
       sigpending(2)		  1.0
       sigprocmask(2)		  1.0
       sigreturn(2)		  1.0
       sigsuspend(2)		  1.0
       socket(2)		  2.0		See notes on socketcall(2)
       socketcall(2)		  1.0
       socketpair(2)		  2.0		See notes on socketcall(2)
       splice(2)		  2.6.17
       spu_create(2)		  2.6.16	PowerPC only
       spu_run(2)		  2.6.16	PowerPC only
       ssetmask(2)		  1.0
       stat(2)			  1.0
       stat64(2)		  2.4
       statfs(2)		  1.0
       statfs64(2)		  2.6
       stime(2)			  1.0
       subpage_prot(2)		  2.6.25	PowerPC only
       swapoff(2)		  1.0
       swapon(2)		  1.0

       symlink(2)		  1.0
       symlinkat(2)		  2.6.16
       sync(2)			  1.0
       sync_file_range(2)	  2.6.17
       sync_file_range2(2)	  2.6.22
       syncfs(2)		  2.6.39
       sysfs(2)			  1.2
       sysinfo(2)		  1.0
       syslog(2)		  1.0
       tee(2)			  2.6.17
       tgkill(2)		  2.6
       time(2)			  1.0
       timer_create(2)		  2.6
       timer_delete(2)		  2.6
       timer_getoverrun(2)	  2.6
       timer_gettime(2)		  2.6
       timer_settime(2)		  2.6
       timerfd_create(2)	  2.6.25
       timerfd_gettime(2)	  2.6.25
       timerfd_settime(2)	  2.6.25
       times(2)			  1.0
       tkill(2)			  2.6; 2.4.22
       truncate(2)		  1.0
       truncate64(2)		  2.4
       ugetrlimit(2)		  2.4
       umask(2)			  1.0
       umount(2)		  1.0
       umount2(2)		  2.2
       uname(2)			  1.0
       unlink(2)		  1.0
       unlinkat(2)		  2.6.16
       unshare(2)		  2.6.16
       uselib(2)		  1.0
       ustat(2)			  1.0
       userfaultfd(2)		  4.2
       utime(2)			  1.0
       utimensat(2)		  2.6.22
       utimes(2)		  2.2
       utrap_install(2)		  2.2		Sparc only
       vfork(2)			  2.2
       vhangup(2)		  1.0
       vm86old(2)		  1.0		Was "vm86"; renamed in
       vm86(2)			  2.0.28; 2.2
       vmsplice(2)		  2.6.17
       wait4(2)			  1.0
       waitid(2)		  2.6.10
       waitpid(2)		  1.0
       write(2)			  1.0
       writev(2)		  2.0

       On many platforms, including x86-32, socket calls are  all  multiplexed
       (via  glibc wrapper functions) through socketcall(2) and similarly Sys-
       tem V IPC calls are multiplexed through ipc(2).

       Although slots are reserved for them in the system call table, the fol-
       lowing  system  calls  are  not	implemented  in	 the  standard kernel:
       afs_syscall(2),	break(2),  ftime(2),  getpmsg(2),  gtty(2),   idle(2),
       lock(2),	 madvise1(2), mpx(2), phys(2), prof(2), profil(2), putpmsg(2),
       security(2), stty(2), tuxcall(2), ulimit(2), and vserver(2)  (see  also
       unimplemented(2)).   However,  ftime(3), profil(3), and ulimit(3) exist
       as library routines.  The slot for  phys(2)  is	in  use	 since	kernel
       2.1.116	 for  umount(2);  phys(2)  will	 never	be  implemented.   The
       getpmsg(2) and putpmsg(2) calls are  for	 kernels  patched  to  support
       STREAMS, and may never be in the standard kernel.

       There  was  briefly  set_zone_reclaim(2),  added	 in  Linux 2.6.13, and
       removed in 2.6.16; this system call was never available to user space.

       Roughly speaking, the code belonging to the  system  call  with	number
       __NR_xxx defined in /usr/include/asm/unistd.h can be found in the Linux
       kernel source in the routine sys_xxx().	(The dispatch table  for  i386
       can  be	found  in /usr/src/linux/arch/i386/kernel/entry.S.)  There are
       many exceptions, however, mostly because older system calls were super-
       seded  by  newer	 ones, and this has been treated somewhat unsystemati-
       cally.  On platforms with proprietary operating-system emulation,  such
       as  parisc, sparc, sparc64, and alpha, there are many additional system
       calls; mips64 also contains a full set of 32-bit system calls.

       Over time, changes to the interfaces of some  system  calls  have  been
       necessary.   One	 reason	 for such changes was the need to increase the
       size of structures or scalar values passed to the system call.  Because
       of  these  changes, certain architectures (notably, longstanding 32-bit
       architectures such as i386) now have various groups of  related	system
       calls  (e.g.,  truncate(2)  and	truncate64(2))	which  perform similar
       tasks, but which vary in details such as the size of  their  arguments.
       (As  noted  earlier,  applications  are	generally unaware of this: the
       glibc wrapper functions do some work to ensure that  the	 right	system
       call  is invoked, and that ABI compatibility is preserved for old bina-
       ries.)  Examples of systems calls that exist in multiple	 versions  are
       the following:

       *  By  now  there  are  three different versions of stat(2): sys_stat()
	  (slot	  __NR_oldstat),   sys_newstat()   (slot    __NR_stat),	   and
	  sys_stat64()	(slot  __NR_stat64), with the last being the most cur-
	  rent.	 A similar story applies for lstat(2) and fstat(2).

       *  Similarly,  the   defines   __NR_oldolduname,	  __NR_olduname,   and
	  __NR_uname  refer  to	 the  routines sys_olduname(), sys_uname() and

       *  In Linux 2.0, a new version of vm86(2) appeared, with	 the  old  and
	  the new kernel routines being named sys_vm86old() and sys_vm86().

       *  In  Linux  2.4, a new version of getrlimit(2) appeared, with the old
	  and the new kernel routines being  named  sys_old_getrlimit()	 (slot
	  __NR_getrlimit) and sys_getrlimit() (slot __NR_ugetrlimit).

       *  Linux	 2.4  increased	 the  size of user and group IDs from 16 to 32
	  bits.	 To support this change, a range of system  calls  were	 added
	  (e.g.,  chown32(2),  getuid32(2),  getgroups32(2),  setresuid32(2)),
	  superseding earlier calls of the same name without the "32" suffix.

       *  Linux 2.4 added support for applications on 32-bit architectures  to
	  access large files (i.e., files for which the sizes and file offsets
	  can't be represented in 32 bits.)  To support this change,  replace-
	  ments were required for system calls that deal with file offsets and
	  sizes.  Thus the following system calls were added: fcntl64(2), get-
	  dents64(2), stat64(2), statfs64(2), truncate64(2), and their analogs
	  that work with file descriptors or  symbolic	links.	 These	system
	  calls	 supersede the older system calls which, except in the case of
	  the "stat" calls, have the same name without the "64" suffix.

	  On newer platforms that only have  64-bit  file  access  and	32-bit
	  UIDs/GIDs (e.g., alpha, ia64, s390x, x86-64), there is just a single
	  version of the UID/GID and file access system calls.	 On  platforms
	  (typically, 32-bit platforms) where the *64 and *32 calls exist, the
	  other versions are obsolete.

       *  The rt_sig* calls were added in kernel 2.2 to support	 the  addition
	  of  real-time signals (see signal(7)).  These system calls supersede
	  the older system calls of the same name without the "rt_" prefix.

       *  The select(2) and mmap(2) system calls use five or  more  arguments,
	  which	 caused	 problems in the way argument passing on the i386 used
	  to be set up.	 Thus, while other architectures have sys_select() and
	  sys_mmap()  corresponding  to __NR_select and __NR_mmap, on i386 one
	  finds old_select() and old_mmap() (routines that use a pointer to an
	  argument block) instead.  These days passing five arguments is not a
	  problem any more, and there is a  __NR__newselect  that  corresponds
	  directly to sys_select() and similarly __NR_mmap2.

       intro(2), syscall(2), unimplemented(2), errno(3), libc(7), vdso(7)

       This  page  is  part of release 4.10 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest	  version     of     this    page,    can    be	   found    at

Linux				  2016-12-12			   SYSCALLS(2)