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authorDmitry Safonov <dima@arista.com>2021-07-27 14:06:35 +0100
committerPetr Mladek <pmladek@suse.com>2021-07-29 16:29:35 +0200
commit10102a890b543a8a08457dc69fa55bc032403c7d (patch)
tree8a39a780a0d740f48f0ff8dae44328577bece30c /kernel/printk
parentc9110dfcfccb3f31eda47a36ed0a022e390d1417 (diff)
downloadlinux-10102a890b543a8a08457dc69fa55bc032403c7d.tar.bz2
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
Diffstat (limited to 'kernel/printk')
-rw-r--r--kernel/printk/printk.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 142a58d124d9..a6b94c3c5ac5 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2404,6 +2404,18 @@ module_param_named(console_suspend, console_suspend_enabled,
MODULE_PARM_DESC(console_suspend, "suspend console during suspend"
" and hibernate operations");
+static bool printk_console_no_auto_verbose;
+
+void console_verbose(void)
+{
+ if (console_loglevel && !printk_console_no_auto_verbose)
+ console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
+}
+EXPORT_SYMBOL_GPL(console_verbose);
+
+module_param_named(console_no_auto_verbose, printk_console_no_auto_verbose, bool, 0644);
+MODULE_PARM_DESC(console_no_auto_verbose, "Disable console loglevel raise to highest on oops/panic/etc");
+
/**
* suspend_console - suspend the console subsystem
*