linux64(1) - phpMan

SETARCH(8) System Administration SETARCH(8)

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

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

setarch --list|-h|-V

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

DESCRIPTION
setarch modifies execution domains and process personality flags.

The execution domains 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 de-
fault program is /bin/sh.

Since version 2.33 the arch command line argument is optional and setarch may be used to
change personality flags (ADDR_LIMIT_*, SHORT_INODE, etc) without modification of the exe-
cution domain.

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

--uname-2.6
Causes the program to see a kernel version number beginning with 2.6. Turns on UN-
AME26.

-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 Al-
pha. Turns on ADDR_LIMIT_32BIT.

-F, --fdpic-funcptrs
Treat user-space function pointers to signal handlers as pointers to address de-
scriptors. This option has no effect on architectures 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_COMPAT_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 inter-
rupted by a signal handler. Use when program depends on this behavior. For more
details see the timeout 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 --addr-no-randomize mytestprog
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 AT redhat.com>
Jindrich Novy <jnovy AT redhat.com>
Karel Zak <kzak AT redhat.com>