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| author | Dave Young <hidave.darkstar@gmail.com> | 2009-09-23 01:43:33 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-23 16:39:28 +0200 |
| commit | af91322ef3f29ae4114e736e2a72e28b4d619cf9 (patch) | |
| tree | debba08531c7dd78b90b5d8f2c03f6bf7c9e7877 /kernel/printk.c | |
| parent | printk boot_delay: rename printk_delay_msec to loops_per_msec (diff) | |
| download | linux-af91322ef3f29ae4114e736e2a72e28b4d619cf9.tar.xz linux-af91322ef3f29ae4114e736e2a72e28b4d619cf9.zip | |
printk: add printk_delay to make messages readable for some scenarios
When syslog is not possible, at the same time there's no serial/net
console available, it will be hard to read the printk messages. For
example oops/panic/warning messages in shutdown phase.
Add a printk delay feature, we can make each printk message delay some
milliseconds.
Setting the delay by proc/sysctl interface: /proc/sys/kernel/printk_delay
The value range from 0 - 10000, default value is 0
[akpm@linux-foundation.org: fix a few things]
Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/printk.c')
| -rw-r--r-- | kernel/printk.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/kernel/printk.c b/kernel/printk.c index 932ea21feb18..f38b07f78a4e 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -653,6 +653,20 @@ static int recursion_bug; static int new_text_line = 1; static char printk_buf[1024]; +int printk_delay_msec __read_mostly; + +static inline void printk_delay(void) +{ + if (unlikely(printk_delay_msec)) { + int m = printk_delay_msec; + + while (m--) { + mdelay(1); + touch_nmi_watchdog(); + } + } +} + asmlinkage int vprintk(const char *fmt, va_list args) { int printed_len = 0; @@ -662,6 +676,7 @@ asmlinkage int vprintk(const char *fmt, va_list args) char *p; boot_delay_msec(); + printk_delay(); preempt_disable(); /* This stops the holder of console_sem just where we want him */ |