linux/kernel/printk
Dmitry Safonov 10102a890b printk: Add printk.console_no_auto_verbose boot parameter
console_verbose() increases console loglevel to
CONSOLE_LOGLEVEL_MOTORMOUTH, which provides more information
to debug a panic/oops.

Unfortunately, in Arista we maintain some DUTs (Device Under Test) that
are configured to have 9600 baud rate. While verbose console messages
have their value to post-analyze crashes, on such setup they:
- may prevent panic/oops messages being printed
- take too long to flush on console resulting in watchdog reboot

In all our setups we use kdump which saves dmesg buffer after panic,
so in reality those extra messages on console provide no additional value,
but rather add risk of not getting to __crash_kexec().

Provide printk.console_no_auto_verbose boot parameter, which allows
to switch off printk being verbose on oops/panic/lockdep.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210727130635.675184-3-dima@arista.com
2021-07-29 16:29:35 +02:00
..
braille.c printk: Replace strncmp() with str_has_prefix() 2019-08-16 09:54:08 +02:00
braille.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
console_cmdline.h printk: Fix preferred console selection with multiple matches 2020-02-18 09:34:42 +01:00
internal.h printk: rename vprintk_func to vprintk 2021-03-30 15:21:18 +02:00
Makefile printk: add lockless ringbuffer 2020-07-10 08:48:19 +02:00
printk_ringbuffer.c Merge branch 'printk-rework' into for-linus 2021-01-21 16:06:21 +01:00
printk_ringbuffer.h printk: rectify kernel-doc for prb_rec_init_wr() 2021-01-26 11:17:51 +01:00
printk_safe.c printk: Move EXPORT_SYMBOL() closer to vprintk definition 2021-06-16 10:42:19 +02:00
printk.c printk: Add printk.console_no_auto_verbose boot parameter 2021-07-29 16:29:35 +02:00