linux64

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 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 compati‐ bility only, and may be removed in future releases. -B, --32bit Limit the address space to 32 bits to emulate hardware. Sup‐ ported on ARM and Alpha. Turns on ADDR_LIMIT_32BIT. -F, --fdpic-funcptrs Treat user-space function pointers to signal handlers as point‐ ers to address descriptors. This option has no effect on archi‐ tectures that do not support FDPIC ELF binaries. In kernel v4.14 support is limited to ARM, Blackfin, Fujitsu FR-V, and Su‐ perH 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 pro‐ gram 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 pre‐ serve 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(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 encoun‐ ters 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

AVAILABILITY

The setarch command is part of the util-linux package and is available from Linux Kernel Archive ⟨https://www.kernel.org/pub/linux/utils/util- linux/⟩.

SEE ALSO

personality(2), select(2)

AUTHOR

Elliot Lee ⟨sopwith@redhat.com⟩ Jindrich Novy ⟨jnovy@redhat.com⟩ Karel Zak ⟨kzak@redhat.com⟩

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