SETARCH(8)						       System Administration							SETARCH(8)

NAME

       setarch - change reported architecture in new program environment and set personality flags

SYNOPSIS

       setarch arch [options] [program [argument...]]

       arch [options] [program [argument...]]

       setarch --list|-h|-V

DESCRIPTION

       setarch currently only affects the output of uname -m.  For example, on an AMD64 system, running setarch i386 program will cause program to
       see i686 instead of x86_64 as the machine type.	It also allows to set various personality options.  The default program is /bin/sh.

OPTIONS

       --list List the architectures that setarch knows about.	Whether setarch can actually set each of these architectures depends on  the  run-
	      ning kernel.

       --uname-2.6
	      Causes the program to see a kernel version number beginning with 2.6.  Turns on UNAME26.

       -v, --verbose
	      Be verbose.

       -3, --3gb
	      Specifies program should use a maximum of 3GB of address space.  Supported on x86.  Turns on ADDR_LIMIT_3GB.

       --4gb  This option has no effect.  It is retained for backward compatibility only, and may be removed in future releases.

       -B, --32bit
	      Limit the address space to 32 bits to emulate hardware.  Supported on ARM and Alpha.  Turns on ADDR_LIMIT_32BIT.

       -F, --fdpic-funcptrs
	      Treat  user-space  function  pointers to signal handlers as pointers to address descriptors.  This option has no effect on architec-
	      tures that do not support FDPIC ELF binaries.  In kernel v4.14 support is limited to ARM, Blackfin, Fujitsu  FR-V,  and  SuperH  CPU
	      architectures.

       -I, --short-inode
	      Obsolete bug emulation flag.  Turns on SHORT_INODE.

       -L, --addr-compat-layout
	      Provide legacy virtual address space layout.  Use when the program binary does not have PT_GNU_STACK ELF header.	Turns on ADDR_COM-
	      PAT_LAYOUT.

       -R, --addr-no-randomize
	      Disables randomization of the virtual address space.  Turns on ADDR_NO_RANDOMIZE.

       -S, --whole-seconds
	      Obsolete bug emulation flag.  Turns on WHOLE_SECONDS.

       -T, --sticky-timeouts
	      This makes select(2), pselect(2), and ppoll(2) system calls preserve the timeout value instead of modifying it to reflect the amount
	      of  time not slept when interrupted by a signal handler.	Use when program depends on this behavior.  For more details see the time-
	      out description in select(2) manual page.  Turns on STICKY_TIMEOUTS.

       -X, --read-implies-exec
	      If this is set then mmap(3) PROT_READ will also add the PROT_EXEC bit - as expected by legacy x86 binaries.   Notice  that  the  ELF
	      loader will automatically set this bit when it encounters a legacy binary.  Turns on READ_IMPLIES_EXEC.

       -Z, --mmap-page-zero
	      SVr4  bug emulation that will set mmap(3) page zero as read-only.  Use when program depends on this behavior, and the source code is
	      not available to be fixed.  Turns on MMAP_PAGE_ZERO.

       -V, --version
	      Display version information and exit.

       -h, --help
	      Display help text and exit.

EXAMPLES

       setarch ppc32 rpmbuild --target=ppc --rebuild foo.src.rpm
       setarch ppc32 -v -vL3 rpmbuild --target=ppc --rebuild bar.src.rpm
       setarch ppc32 --32bit rpmbuild --target=ppc --rebuild foo.src.rpm

AUTHOR

       Elliot Lee <sopwith@redhat.com>
       Jindrich Novy <jnovy@redhat.com>

SEE ALSO

       personality(2), select(2)

AVAILABILITY

       The setarch command is part of the util-linux package and is available from Linux  Kernel  Archive  <https://www.kernel.org/pub/linux/utils
       /util-linux/>.

util-linux							   December 2017							SETARCH(8)