NAME

       personality - set the process execution domain

SYNOPSIS

       #include <sys/personality.h>

       int personality(unsigned long persona);

DESCRIPTION

       Linux  supports  different  execution  domains,  or personalities, for each process.  Among other things,
       execution domains tell Linux how to map signal numbers into signal actions.  The execution domain  system
       allows Linux to provide limited support for binaries compiled under other UNIX-like operating systems.

       If  persona  is  not  0xffffffff,  then  personality()  sets  the  caller's execution domain to the value
       specified by persona.  Specifying persona as 0xffffffff provides a way of retrieving the current  persona
       without changing it.

       A list of the available execution domains can be found in <sys/personality.h>.  The execution domain is a
       32-bit  value  in  which  the top three bytes are set aside for flags that cause the kernel to modify the
       behavior of certain system calls so  as  to  emulate  historical  or  architectural  quirks.   The  least
       significant  byte  is  a value defining the personality the kernel should assume.  The flag values are as
       follows:

       ADDR_COMPAT_LAYOUT (since Linux 2.6.9)
              With this flag set, provide legacy virtual address space layout.

       ADDR_NO_RANDOMIZE (since Linux 2.6.12)
              With this flag set, disable address-space-layout randomization.

       ADDR_LIMIT_32BIT (since Linux 2.2)
              Limit the address space to 32 bits.

       ADDR_LIMIT_3GB (since Linux 2.4.0)
              With this flag set, use 0xc0000000 as the offset at which to search  a  virtual  memory  chunk  on
              mmap(2); otherwise use 0xffffe000.

       FDPIC_FUNCPTRS (since Linux 2.6.11)
              User-space function pointers to signal handlers point (on certain architectures) to descriptors.

       MMAP_PAGE_ZERO (since Linux 2.4.0)
              Map page 0 as read-only (to support binaries that depend on this SVr4 behavior).

       READ_IMPLIES_EXEC (since Linux 2.6.8)
              With this flag set, PROT_READ implies PROT_EXEC for mmap(2).

       SHORT_INODE (since Linux 2.4.0)
              No effects(?).

       STICKY_TIMEOUTS (since Linux 1.2.0)
              With  this  flag  set,  select(2),  pselect(2),  and  ppoll(2)  do not modify the returned timeout
              argument when interrupted by a signal handler.

       UNAME26 (since Linux 3.1)
              Have uname(2) report a 2.6.40+ version number rather than  a  3.x  version  number.   Added  as  a
              stopgap  measure to support broken applications that could not handle the kernel version-numbering
              switch from 2.6.x to 3.x.

       WHOLE_SECONDS (since Linux 1.2.0)
              No effects(?).

       The available execution domains are:

       PER_BSD (since Linux 1.2.0)
              BSD. (No effects.)

       PER_HPUX (since Linux 2.4)
              Support for 32-bit HP/UX.  This support was never complete, and was dropped so  that  since  Linux
              4.0, this value has no effect.

       PER_IRIX32 (since Linux 2.2)
              IRIX 5 32-bit.  Never fully functional; support dropped in Linux 2.6.27.  Implies STICKY_TIMEOUTS.

       PER_IRIX64 (since Linux 2.2)
              IRIX 6 64-bit.  Implies STICKY_TIMEOUTS; otherwise no effects.

       PER_IRIXN32 (since Linux 2.2)
              IRIX 6 new 32-bit.  Implies STICKY_TIMEOUTS; otherwise no effects.

       PER_ISCR4 (since Linux 1.2.0)
              Implies STICKY_TIMEOUTS; otherwise no effects.

       PER_LINUX (since Linux 1.2.0)
              Linux.

       PER_LINUX32 (since Linux 2.2)
              [To be documented.]

       PER_LINUX32_3GB (since Linux 2.4)
              Implies ADDR_LIMIT_3GB.

       PER_LINUX_32BIT (since Linux 2.0)
              Implies ADDR_LIMIT_32BIT.

       PER_LINUX_FDPIC (since Linux 2.6.11)
              Implies FDPIC_FUNCPTRS.

       PER_OSF4 (since Linux 2.4)
              OSF/1  v4.  On alpha, clear top 32 bits of iov_len in the user's buffer for compatibility with old
              versions of OSF/1 where iov_len was defined as.  int.

       PER_OSR5 (since Linux 2.4)
              Implies STICKY_TIMEOUTS and WHOLE_SECONDS; otherwise no effects.

       PER_RISCOS (since Linux 2.2)
              [To be documented.]

       PER_SCOSVR3 (since Linux 1.2.0)
              Implies STICKY_TIMEOUTS, WHOLE_SECONDS, and SHORT_INODE; otherwise no effects.

       PER_SOLARIS (since Linux 2.4)
              Implies STICKY_TIMEOUTS; otherwise no effects.

       PER_SUNOS (since Linux 2.4.0)
              Implies STICKY_TIMEOUTS.  Divert library and  dynamic  linker  searches  to  /usr/gnemul.   Buggy,
              largely unmaintained, and almost entirely unused; support was removed in Linux 2.6.26.

       PER_SVR3 (since Linux 1.2.0)
              Implies STICKY_TIMEOUTS and SHORT_INODE; otherwise no effects.

       PER_SVR4 (since Linux 1.2.0)
              Implies STICKY_TIMEOUTS and MMAP_PAGE_ZERO; otherwise no effects.

       PER_UW7 (since Linux 2.4)
              Implies STICKY_TIMEOUTS and MMAP_PAGE_ZERO; otherwise no effects.

       PER_WYSEV386 (since Linux 1.2.0)
              Implies STICKY_TIMEOUTS and SHORT_INODE; otherwise no effects.

       PER_XENIX (since Linux 1.2.0)
              Implies STICKY_TIMEOUTS and SHORT_INODE; otherwise no effects.

RETURN VALUE

       On success, the previous persona is returned.  On error, -1 is returned, and errno is set appropriately.

ERRORS

       EINVAL The kernel was unable to change the personality.

VERSIONS

       This  system  call  first  appeared in Linux 1.1.20 (and thus first in a stable kernel release with Linux
       1.2.0); library support was added in glibc 2.3.

CONFORMING TO

       personality() is Linux-specific and should not be used in programs intended to be portable.

SEE ALSO

       setarch(8)

COLOPHON

       This page is part of release 5.10 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
       https://www.kernel.org/doc/man-pages/.

Linux                                              2017-09-15                                     PERSONALITY(2)