Add more information when and why one might want to use various options. Signed-off-by: Sami Kerola <kerolasa@xxxxxx> --- sys-utils/setarch.8 | 51 +++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 41 insertions(+), 10 deletions(-) diff --git a/sys-utils/setarch.8 b/sys-utils/setarch.8 index 73874c8b6..ce7ba97ac 100644 --- a/sys-utils/setarch.8 +++ b/sys-utils/setarch.8 @@ -1,4 +1,4 @@ -.TH SETARCH 8 "December 2014" "util-linux" "System Administration" +.TH SETARCH 8 "December 2017" "util-linux" "System Administration" .SH NAME setarch \- change reported architecture in new program environment and set personality flags .SH SYNOPSIS @@ -30,41 +30,70 @@ can actually set each of these architectures depends on the running kernel. .TP .B \-\-uname\-2.6 Causes the \fIprogram\fR to see a kernel version number beginning with 2.6. +Turns on UNAME26. .TP .BR \-v , " \-\-verbose" Be verbose. .TP \fB\-3\fR, \fB\-\-3gb\fR -Specifies that processes should use a maximum of 3GB of address space on systems where it is supported (ADDR_LIMIT_3GB). +Specifies +.I program +should use a maximum of 3GB of address space. Supported on x86 (as of +2017-12-02). Turns on ADDR_LIMIT_3GB. .TP \fB\-\-4gb\fR -Ignored (for backward compatibility only). +Ignored for backward compatibility only. .TP \fB\-B\fR, \fB\-\-32bit\fR -Turns on ADDR_LIMIT_32BIT. +Limit the address space to 32 bits to emulate hardware. Supported on ARM +and Alpha (as of 2017-12-02). Turns on ADDR_LIMIT_32BIT. .TP \fB\-F\fR, \fB\-\-fdpic\-funcptrs\fR -Userspace function pointers point to descriptors (turns on FDPIC_FUNCPTRS). +User-space function pointers to signal handlers point. Use when kernel does +not have MMU. Supported on ARM, Blackfin, Fujitsu FR-V, and SuperH (as of +2017-12-02). Turns on FDPIC_FUNCPTRS. .TP \fB\-I\fR, \fB\-\-short\-inode\fR -Turns on SHORT_INODE. +Obsolete bug emulation flag. Turns on SHORT_INODE. .TP \fB\-L\fR, \fB\-\-addr\-compat\-layout\fR -Changes the way virtual memory is allocated (turns on the ADDR_COMPAT_LAYOUT). +Provide legacy virtual address space layout. Use when the +.I program +binary does not have PT_GNU_STACK ELF header. Turns on +ADDR_COMPAT_LAYOUT. .TP \fB\-R\fR, \fB\-\-addr\-no\-randomize\fR -Disables randomization of the virtual address space (turns on ADDR_NO_RANDOMIZE). +Disables randomization of the virtual address space. Turns on +ADDR_NO_RANDOMIZE. .TP \fB\-S\fR, \fB\-\-whole\-seconds\fR -Turns on WHOLE_SECONDS. +Obsolete bug emulation flag. Turns on WHOLE_SECONDS. .TP \fB\-T\fR, \fB\-\-sticky\-timeouts\fR +This makes +.BR select (2), +.BR pselect (2), +and +.BR ppoll (2) +system calls preserve the timeout value instead of storing the unslept time +when interrupted by a signal handler. Use when +.I program +depends on this behavior, and the source code is not available to be fixed. Turns on STICKY_TIMEOUTS. .TP \fB\-X\fR, \fB\-\-read\-implies\-exec\fR -Turns on READ_IMPLIES_EXEC. +If this is set then +.BR 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 encounters a legacy binary. Turns on READ_IMPLIES_EXEC. .TP \fB\-Z\fR, \fB\-\-mmap\-page\-zero\fR +SVr4 bug emulation that will set +.BR mmap (3) +page zero as read-only. Use when +.I program +depends on this behavior, and the source code is not available to be fixed. Turns on MMAP_PAGE_ZERO. .TP .BR \-V , " \-\-version" @@ -86,6 +115,8 @@ Elliot Lee .MT jnovy@xxxxxxxxxx Jindrich Novy .ME +.SH "SEE ALSO" +.BR personality (2) .SH AVAILABILITY The setarch command is part of the util-linux package and is available from .UR https://\:www.kernel.org\:/pub\:/linux\:/utils\:/util-linux/ -- 2.15.1 -- To unsubscribe from this list: send the line "unsubscribe util-linux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
