On Tue 2018-12-18 12:37:48, Steven Rostedt wrote: > On Tue, 18 Dec 2018 18:21:09 +0100 > Peter Zijlstra <pet...@infradead.org> wrote: > > > On Wed, Dec 19, 2018 at 01:52:17AM +0900, Sergey Senozhatsky wrote: > > > On (12/18/18 16:24), Borislav Petkov wrote: > > > > On Wed, Dec 19, 2018 at 12:14:55AM +0900, Sergey Senozhatsky wrote: > > > > > Right, but unlike log_buf_len, devkmsg is a bit close to a "binary" > > > > > knob: > > > > > either all messages or none; > > > > > > > > ... which is perfectly fine for a debugging session. > > > > > > But devkmsg ratelimits systemd errors, so one does not even know that > > > "some debugging is required". For instance from my x86 box: > > > > > > Unmounting /home... > > > [..] > > > home.mount: Mount process exited, code=exited status=32 > > > Failed unmounting /home. > > > > > > I don't want to debug systemd, I want to know that something didn't > > > work out. 10 messages max and 5 seconds interval looks a bit too strict. > > > > Again, complain to system-doofus for printing so much crap to somewhere > > it should not print to begin with. > > I've been saying that it would be good to make the kmsg be a separate > buffer that just gets interleaved with the kernel buffer. Userspace > processes should never be able to overwrite messages from the kernel.
There was a proposal for this few years ago, see https://lkml.kernel.org/r/1435920595-30879-1-git-send-email-m.niesluc...@samsung.com Honestly, I got scared. It proposed an interface for dynamically adding separate /dev/kmsg devices and related log buffers. This smells with huge amount of messages that might fight for console throughput and complicate printk code. Best Regards, Petr