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
           Print 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 at 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/>.