Messages in this thread | | | Date | Fri, 04 Apr 2014 11:21:38 -0700 | From | Andy Lutomirski <> | Subject | Re: [RFC PATCH] cmdline: Hide "debug" from /proc/cmdline |
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On 04/03/2014 10:05 AM, Theodore Ts'o wrote: > On Thu, Apr 03, 2014 at 12:43:08PM +0200, Joerg Roedel wrote: >> >> How about just ignoring writes to /dev/kmsg altogether by default >> (unless explicitly enabled in Kconfig or on the kernel cmdline)? Maybe I >> am missing something but what are the legitimate use-cases for generally >> allowing user-space to write into the kernel-log? > > I'll give you one example which where /dev/kmesg is useful --- if you > are running automated kernel tests, echoing "running test shared/127" > .... several minutes later .... "running test shared/128", is very > useful since if the kernel starts spewing warnings, or even > oops/panics/livelocks, you know what test was running at the time of > the failure.
I'm using /dev/kmsg in virtme so that I can easily capture, with timestamps, the ten or so log lines that it produces. It would be sad if I had to worry about small ratelimits here.
/dev/kmsg is genuinely useful for the case where an initramfs wants to log something (preferably only a little bit) and doesn't want to invent a whole protocol for passing logging data through to the final logging system.
The other thing I've used /dev/kmsg for is to shove a "I'm starting something now" message in. This is only really necessary because the current kernel log timestamps are unusable crap. (We could fix that, hint hint.)
--Andy
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