SETARCH
Section: System Administration (8)
Updated: December 2017
Page Index
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 can also be used to set various personality options.
The default 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 execution 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 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 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 interrupted 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(3p)
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(3p)
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.
EXAMPLE
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
AUTHORS
Elliot Lee
Jindrich Novy
Karel Zak
SEE ALSO
personality(2),
select(2)
AVAILABILITY
The setarch command is part of the util-linux package and is available from
Linux Kernel Archive