diff options
| -rw-r--r-- | Documentation/admin-guide/sysrq.rst | 9 | ||||
| -rw-r--r-- | drivers/tty/sysrq.c | 13 |
2 files changed, 21 insertions, 1 deletions
diff --git a/Documentation/admin-guide/sysrq.rst b/Documentation/admin-guide/sysrq.rst index 2f2e5bd440f9..a85b3384d1e7 100644 --- a/Documentation/admin-guide/sysrq.rst +++ b/Documentation/admin-guide/sysrq.rst @@ -161,6 +161,8 @@ Command Function will be printed to your console. (``0``, for example would make it so that only emergency messages like PANICs or OOPSes would make it to your console.) + +``R`` Replay the kernel log messages on consoles. =========== =================================================================== Okay, so what can I use them for? @@ -211,6 +213,13 @@ processes. "just thaw ``it(j)``" is useful if your system becomes unresponsive due to a frozen (probably root) filesystem via the FIFREEZE ioctl. +``Replay logs(R)`` is useful to view the kernel log messages when system is hung +or you are not able to use dmesg command to view the messages in printk buffer. +User may have to press the key combination multiple times if console system is +busy. If it is completely locked up, then messages won't be printed. Output +messages depend on current console loglevel, which can be modified using +sysrq[0-9] (see above). + Sometimes SysRq seems to get 'stuck' after using it, what can I do? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index 02217e3c916b..e5974b8239c9 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -450,6 +450,17 @@ static const struct sysrq_key_op sysrq_unrt_op = { .enable_mask = SYSRQ_ENABLE_RTNICE, }; +static void sysrq_handle_replay_logs(u8 key) +{ + console_replay_all(); +} +static struct sysrq_key_op sysrq_replay_logs_op = { + .handler = sysrq_handle_replay_logs, + .help_msg = "replay-kernel-logs(R)", + .action_msg = "Replay kernel logs on consoles", + .enable_mask = SYSRQ_ENABLE_DUMP, +}; + /* Key Operations table and lock */ static DEFINE_SPINLOCK(sysrq_key_table_lock); @@ -519,7 +530,7 @@ static const struct sysrq_key_op *sysrq_key_table[62] = { NULL, /* O */ NULL, /* P */ NULL, /* Q */ - NULL, /* R */ + &sysrq_replay_logs_op, /* R */ NULL, /* S */ NULL, /* T */ NULL, /* U */ |