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[PATCH] kdump: sysrq trigger mechanism for kexec based crashdumps

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Add a sysrq-trigger mechanism for kexec based crashdumps.  Alt-Sysrq-c
triggers a kexec based crashdump.

Signed-off-by: Hariprasad Nellitheertha <hari@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Hariprasad Nellitheertha 2005-06-25 14:58:25 -07:00 committed by Linus Torvalds
parent 315c215c0a
commit 86b1ae38c0
2 changed files with 27 additions and 2 deletions
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5
Documentation/sysrq.txt
View file

@ -72,6 +72,8 @@ On all - write a character to /proc/sysrq-trigger. eg:
'b' - Will immediately reboot the system without syncing or unmounting 'b' - Will immediately reboot the system without syncing or unmounting
your disks. your disks.
'c' - Will perform a kexec reboot in order to take a crashdump.
'o' - Will shut your system off (if configured and supported). 'o' - Will shut your system off (if configured and supported).
's' - Will attempt to sync all mounted filesystems. 's' - Will attempt to sync all mounted filesystems.
@ -122,6 +124,9 @@ useful when you want to exit a program that will not let you switch consoles.
re'B'oot is good when you're unable to shut down. But you should also 'S'ync re'B'oot is good when you're unable to shut down. But you should also 'S'ync
and 'U'mount first. and 'U'mount first.
'C'rashdump can be used to manually trigger a crashdump when the system is hung.
The kernel needs to have been built with CONFIG_KEXEC enabled.
'S'ync is great when your system is locked up, it allows you to sync your 'S'ync is great when your system is locked up, it allows you to sync your
disks and will certainly lessen the chance of data loss and fscking. Note disks and will certainly lessen the chance of data loss and fscking. Note
that the sync hasn't taken place until you see the "OK" and "Done" appear that the sync hasn't taken place until you see the "OK" and "Done" appear

24
drivers/char/sysrq.c
View file

@ -35,6 +35,7 @@
#include <linux/spinlock.h> #include <linux/spinlock.h>
#include <linux/vt_kern.h> #include <linux/vt_kern.h>
#include <linux/workqueue.h> #include <linux/workqueue.h>
#include <linux/kexec.h>
#include <asm/ptrace.h> #include <asm/ptrace.h>
@ -94,6 +95,21 @@ static struct sysrq_key_op sysrq_unraw_op = {
}; };
#endif /* CONFIG_VT */ #endif /* CONFIG_VT */
#ifdef CONFIG_KEXEC
/* crashdump sysrq handler */
static void sysrq_handle_crashdump(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
crash_kexec();
}
static struct sysrq_key_op sysrq_crashdump_op = {
.handler = sysrq_handle_crashdump,
.help_msg = "Crashdump",
.action_msg = "Trigger a crashdump",
.enable_mask = SYSRQ_ENABLE_DUMP,
};
#endif
/* reboot sysrq handler */ /* reboot sysrq handler */
static void sysrq_handle_reboot(int key, struct pt_regs *pt_regs, static void sysrq_handle_reboot(int key, struct pt_regs *pt_regs,
struct tty_struct *tty) struct tty_struct *tty)
@ -273,8 +289,12 @@ static struct sysrq_key_op *sysrq_key_table[SYSRQ_KEY_TABLE_LENGTH] = {
it is handled specially on the sparc it is handled specially on the sparc
and will never arrive */ and will never arrive */
/* b */ &sysrq_reboot_op, /* b */ &sysrq_reboot_op,
/* c */ NULL, #ifdef CONFIG_KEXEC
/* d */ NULL, /* c */ &sysrq_crashdump_op,
#else
/* c */ NULL,
#endif
/* d */ NULL,
/* e */ &sysrq_term_op, /* e */ &sysrq_term_op,
/* f */ &sysrq_moom_op, /* f */ &sysrq_moom_op,
/* g */ NULL, /* g */ NULL,