setarch(8) - 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 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 <sopwith AT redhat.com>, Jindrich Novy <jnovy AT redhat.com>, Karel Zak
<kzak AT redhat.com>