sys-utils/setarch.8

   1 .TH SETARCH 8 "December 2017" "util-linux" "System Administration"
   2 .SH NAME
   3 setarch \- change reported architecture in new program environment and/or set personality flags
   4 .SH SYNOPSIS
   5 .B setarch
   6 .RI [ arch ]
   7 [options]
   8 .RI [ program
   9 .RI [ argument ...]]
  10 .sp
  11 .B setarch
  12 .BR \-\-list | \-h | \-V
  13 .sp
  14 .B arch
  15 [options]
  16 .RI [ program
  17 .RI [ argument ...]]
  18 .SH DESCRIPTION
  19 .B setarch
  20 modifies execution domains and process personality flags.
  21 .PP
  22 The execution domains currently only affects the output of \fBuname \-m\fR.
  23 For example, on an AMD64 system, running \fBsetarch i386 \fIprogram\fR
  24 will cause \fIprogram\fR to see i686 instead of x86_64 as the machine type.
  25 It also allows to set various personality options.
  26 The default \fIprogram\fR is \fB/bin/sh\fR.
  27 .PP
  28 Since version 2.33 the
  29 .I arch
  30 command line argument is optional and
  31 .B setarch
  32 may be used to change personality flags (ADDR_LIMIT_*, SHORT_INODE, etc) without
  33 modification of the execution domain.
  34 .SH OPTIONS
  35 .TP
  36 .B \-\-list
  37 List the architectures that \fBsetarch\fR knows about.  Whether \fBsetarch\fR
  38 can actually set each of these architectures depends on the running kernel.
  39 .TP
  40 .B \-\-uname\-2.6
  41 Causes the \fIprogram\fR to see a kernel version number beginning with 2.6.
  42 Turns on UNAME26.
  43 .TP
  44 .BR \-v , " \-\-verbose"
  45 Be verbose.
  46 .TP
  47 \fB\-3\fR, \fB\-\-3gb\fR
  48 Specifies
  49 .I program
  50 should use a maximum of 3GB of address space.  Supported on x86.  Turns on
  51 ADDR_LIMIT_3GB.
  52 .TP
  53 \fB\-\-4gb\fR
  54 This option has no effect.  It is retained for backward compatibility only,
  55 and may be removed in future releases.
  56 .TP
  57 \fB\-B\fR, \fB\-\-32bit\fR
  58 Limit the address space to 32 bits to emulate hardware.  Supported on ARM
  59 and Alpha.  Turns on ADDR_LIMIT_32BIT.
  60 .TP
  61 \fB\-F\fR, \fB\-\-fdpic\-funcptrs\fR
  62 Treat user-space function pointers to signal handlers as pointers to address
  63 descriptors.  This option has no effect on architectures that do not support
  64 FDPIC ELF binaries.  In kernel v4.14 support is limited to ARM, Blackfin,
  65 Fujitsu FR-V, and SuperH CPU architectures.
  66 .TP
  67 \fB\-I\fR, \fB\-\-short\-inode\fR
  68 Obsolete bug emulation flag.  Turns on SHORT_INODE.
  69 .TP
  70 \fB\-L\fR, \fB\-\-addr\-compat\-layout\fR
  71 Provide legacy virtual address space layout.  Use when the
  72 .I program
  73 binary does not have PT_GNU_STACK ELF header.  Turns on
  74 ADDR_COMPAT_LAYOUT.
  75 .TP
  76 \fB\-R\fR, \fB\-\-addr\-no\-randomize\fR
  77 Disables randomization of the virtual address space.  Turns on
  78 ADDR_NO_RANDOMIZE.
  79 .TP
  80 \fB\-S\fR, \fB\-\-whole\-seconds\fR
  81 Obsolete bug emulation flag.  Turns on WHOLE_SECONDS.
  82 .TP
  83 \fB\-T\fR, \fB\-\-sticky\-timeouts\fR
  84 This makes
  85 .BR select (2),
  86 .BR pselect (2),
  87 and
  88 .BR ppoll (2)
  89 system calls preserve the timeout value instead of modifying it to reflect
  90 the amount of time not slept when interrupted by a signal handler.  Use when
  91 .I program
  92 depends on this behavior.  For more details see the timeout description in
  93 .BR select (2)
  94 manual page.  Turns on STICKY_TIMEOUTS.
  95 .TP
  96 \fB\-X\fR, \fB\-\-read\-implies\-exec\fR
  97 If this is set then
  98 .BR mmap (3p)
  99 PROT_READ will also add the PROT_EXEC bit - as expected by legacy x86
 100 binaries.  Notice that the ELF loader will automatically set this bit when
 101 it encounters a legacy binary.  Turns on READ_IMPLIES_EXEC.
 102 .TP
 103 \fB\-Z\fR, \fB\-\-mmap\-page\-zero\fR
 104 SVr4 bug emulation that will set
 105 .BR mmap (3p)
 106 page zero as read-only.  Use when
 107 .I program
 108 depends on this behavior, and the source code is not available to be fixed.
 109 Turns on MMAP_PAGE_ZERO.
 110 .TP
 111 .BR \-V , " \-\-version"
 112 Display version information and exit.
 113 .TP
 114 .BR \-h , " \-\-help"
 115 Display help text and exit.
 116 .SH EXAMPLES
 117 setarch \-\-addr-no-randomize mytestprog
 118 .br
 119 setarch ppc32 rpmbuild \-\-target=ppc \-\-rebuild foo.src.rpm
 120 .br
 121 setarch ppc32 \-v \-vL3 rpmbuild \-\-target=ppc \-\-rebuild bar.src.rpm
 122 .br
 123 setarch ppc32 \-\-32bit rpmbuild \-\-target=ppc \-\-rebuild foo.src.rpm
 124 .SH AUTHORS
 125 .MT sopwith@redhat.com
 126 Elliot Lee
 127 .ME
 128 .br
 129 .MT jnovy@redhat.com
 130 Jindrich Novy
 131 .ME
 132 .br
 133 .MT kzak@redhat.com
 134 Karel Zak
 135 .ME
 136 .SH SEE ALSO
 137 .BR personality (2),
 138 .BR select (2)
 139 .SH AVAILABILITY
 140 The setarch command is part of the util-linux package and is available from
 141 .UR https://\:www.kernel.org\:/pub\:/linux\:/utils\:/util-linux/
 142 Linux Kernel Archive
 143 .UE .