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 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.
--show[=personality]
Show the currently active personality and flags. If the personality
argument is provided, it is shown instead of the current one.
personality is a hexadecimal number with values was described in
sys/personality.h.
--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(2) 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(2) 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.
-h, --help
Display help text and exit.
-V, --version
Display version 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 <sopwith@redhat.com>, Jindrich Novy <jnovy@redhat.com>, Karel
Zak <kzak@redhat.com>
SEE ALSO
personality(2), select(2)
REPORTING BUGS
For bug reports, use the issue tracker
<https://github.com/util-linux/util-linux/issues>.
AVAILABILITY
The setarch command is part of the util-linux package which can be
downloaded from Linux Kernel Archive
<https://www.kernel.org/pub/linux/utils/util-linux/>.
util-linux 2.41 2025-02-26 SETARCH(8)
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