[PATCH] printk: Add Kconfig option to set default console loglevel
From: Olof Johansson
Date: Sun Nov 20 2016 - 16:20:39 EST
Add a configuration option to set the default console loglevel. This
is, as before, still possible to override at runtime through bootargs
(loglevel=<x>), sysrq and /proc/printk.
There are cases where adding additional arguments on the commandline is
impractical, and changing the default for the kernel when being built
makes more sense. Provide such a method here, for those who choose to
do so.
Also, while touching this code, clarify the difference between
MESSAGE_LOGLEVEL_DEFAULT and CONSOLE_LOGLEVEL_DEFAULT.
Signed-off-by: Olof Johansson <olof@xxxxxxxxx>
---
include/linux/printk.h | 7 ++++++-
lib/Kconfig.debug | 19 +++++++++++++++++++
2 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/include/linux/printk.h b/include/linux/printk.h
index eac1af8502bb..fdd1fc70f1d1 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -40,10 +40,15 @@ static inline const char *printk_skip_level(const char *buffer)
#define CONSOLE_LOGLEVEL_SILENT 0 /* Mum's the word */
#define CONSOLE_LOGLEVEL_MIN 1 /* Minimum loglevel we let people use */
#define CONSOLE_LOGLEVEL_QUIET 4 /* Shhh ..., when booted with "quiet" */
-#define CONSOLE_LOGLEVEL_DEFAULT 7 /* anything MORE serious than KERN_DEBUG */
#define CONSOLE_LOGLEVEL_DEBUG 10 /* issue debug messages */
#define CONSOLE_LOGLEVEL_MOTORMOUTH 15 /* You can't shut this one up */
+/*
+ * Default used to be hard-coded at 7, we're now allowing it to be set from
+ * kernel config.
+ */
+#define CONSOLE_LOGLEVEL_DEFAULT CONFIG_CONSOLE_LOGLEVEL_DEFAULT
+
extern int console_printk[];
#define console_loglevel (console_printk[0])
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index b01e547d4d04..7245b143bf5b 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -15,6 +15,21 @@ config PRINTK_TIME
The behavior is also controlled by the kernel command line
parameter printk.time=1. See Documentation/kernel-parameters.txt
+config CONSOLE_LOGLEVEL_DEFAULT
+ int "Default console loglevel (1-15)"
+ range 1 15
+ default "7"
+ help
+ Default loglevel to determine what will be printed on the console.
+
+ Setting a default here is equivalent to passing in loglevel=<x> in
+ the kernel bootargs. loglevel=<x> continues to override whatever
+ value is specified here as well.
+
+ Note: This does not affect the log level of un-prefixed prink()
+ usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
+ option.
+
config MESSAGE_LOGLEVEL_DEFAULT
int "Default message log level (1-7)"
range 1 7
@@ -26,6 +41,10 @@ config MESSAGE_LOGLEVEL_DEFAULT
that are auditing their logs closely may want to set it to a lower
priority.
+ Note: This does not affect what message level gets printed on the console
+ by default. To change that, use loglevel=<x> in the kernel bootargs,
+ or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
+
config BOOT_PRINTK_DELAY
bool "Delay each boot printk message by N milliseconds"
depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
--
1.9.1