linux-toradex.git/Documentation/sysrq.txt, branch v3.14.42

sysrq: Allow magic SysRq key functions to be disabled through Kconfig

2013-10-16T20:01:44+00:00

Turn the initial value of sysctl kernel.sysrq (SYSRQ_DEFAULT_ENABLE)
into a Kconfig variable.

Original version by Bastian Blank .

Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

sysrq: Document hexadecimal values for kernel.sysrq bitmask

2013-10-16T20:01:44+00:00

It makes more sense to enter a bitmask in hexadecimal rather than
decimal.  Sadly we can't make it read back as hexadecimal.

Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

Documentation/sysrq: fix inconstistent help message of sysrq key

2013-05-01T00:04:10+00:00

Currently help message of /proc/sysrq-trigger highlight its
upper-case characters, like below:

      SysRq : HELP : loglevel(0-9) reBoot Crash terminate-all-tasks(E)
      memory-full-oom-kill(F) kill-all-tasks(I) ...

this would confuse user trigger sysrq by upper-case character, which is
inconsistent with the real lower-case character registed key.

This inconsistent help message will also lead more confused when
26 upper-case letters put into use in future.

This patch fix sysrq documentation.

Signed-off-by: zhangwei(Jovi) 
Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sparc64: Add global PMU register dumping via sysrq.

2012-10-16T16:34:01+00:00

Signed-off-by: David S. Miller

Documentation: sysrq: Crutcher Dunnavant is unavailable

2012-03-30T23:03:15+00:00

Reported-by: Křištof Želechovski 
Signed-off-by: Randy Dunlap 
Signed-off-by: Linus Torvalds

documentation: update sysrq.txt magic sysrq keys

2010-10-27T00:32:41+00:00

Update Documentation/sysrq.txt magic sysrq keys:

 - 'g' is for kgdb (not arch-specific);
 - add 2 new uses for 'v', remove the Voyager info;
 - add 'y' info (SPARC-64 specific);

Signed-off-by: Randy Dunlap 
Cc: Jason Wessel 
Cc: "David S. Miller" 
Cc: "James E.J. Bottomley" 
Cc: David Airlie 
Acked-by: Alexander Shishkin 
Signed-off-by: Linus Torvalds

Input: Documentation/sysrq.txt - update KEY_SYSRQ info

2010-05-19T17:14:15+00:00

While setting up sysrq operation on the XO laptop (which lacks a SysRq
key), i realized that the documentation was quite out of date.

Change documentation of SysRq to reflect current KEY_SYSRQ value.

Signed-off-by: Paul Fox 
Signed-off-by: Randy Dunlap 
Signed-off-by: Dmitry Torokhov

sysrq, kdump: make sysrq-c consistent

2009-07-30T02:10:36+00:00

commit d6580a9f15238b87e618310c862231ae3f352d2d ("kexec: sysrq: simplify
sysrq-c handler") changed the behavior of sysrq-c to unconditional
dereference of NULL pointer.  So in cases with CONFIG_KEXEC, where
crash_kexec() was directly called from sysrq-c before, now it can be said
that a step of "real oops" was inserted before starting kdump.

However, in contrast to oops via SysRq-c from keyboard which results in
panic due to in_interrupt(), oops via "echo c > /proc/sysrq-trigger" will
not become panic unless panic_on_oops=1.  It means that even if dump is
properly configured to be taken on panic, the sysrq-c from proc interface
might not start crashdump while the sysrq-c from keyboard can start
crashdump.  This confuses traditional users of kdump, i.e.  people who
expect sysrq-c to do common behavior in both of the keyboard and proc
interface.

This patch brings the keyboard and proc interface behavior of sysrq-c in
line, by forcing panic_on_oops=1 before oops in sysrq-c handler.

And some updates in documentation are included, to clarify that there is
no longer dependency with CONFIG_KEXEC, and that now the system can just
crash by sysrq-c if no dump mechanism is configured.

Signed-off-by: Hidetoshi Seto 
Cc: Lai Jiangshan 
Cc: Ken'ichi Ohmichi 
Acked-by: Neil Horman 
Acked-by: Vivek Goyal 
Cc: Brayan Arraes 
Cc: Eric W. Biederman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'tracing/core-v2' into tracing-for-linus

2009-04-01T22:49:02+00:00

Conflicts:
	include/linux/slub_def.h
	lib/Kconfig.debug
	mm/slob.c
	mm/slub.c

filesystem freeze: allow SysRq emergency thaw to thaw frozen filesystems

2009-04-01T15:59:17+00:00

Now that the filesystem freeze operation has been elevated to the VFS, and
is just an ioctl away, some sort of safety net for unintentionally frozen
root filesystems may be in order.

The timeout thaw originally proposed did not get merged, but perhaps
something like this would be useful in emergencies.

For example, freeze /path/to/mountpoint may freeze your root filesystem if
you forgot that you had that unmounted.

I chose 'j' as the last remaining character other than 'h' which is sort
of reserved for help (because help is generated on any unknown character).

I've tested this on a non-root fs with multiple (nested) freezers, as well
as on a system rendered unresponsive due to a frozen root fs.

[randy.dunlap@oracle.com: emergency thaw only if CONFIG_BLOCK enabled]
Signed-off-by: Eric Sandeen 
Cc: Takashi Sato 
Signed-off-by: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds