Re: [RFC][PATCH] printk: increase devkmsg write() ratelimit

Sergey Senozhatsky
2018-12-18T15:15:01Z

On (12/18/18 16:03), Borislav Petkov wrote:
> On Tue, Dec 18, 2018 at 11:55:58PM +0900, Sergey Senozhatsky wrote:
> > Good question. Theoretically, there can be some interesting stuff.
> > Examples: https://bugzilla.redhat.com/show_bug.cgi?id=1515373#c6
> > or https://github.com/systemd/systemd/issues/5433
>
> Just like that last page says, people should use the printk.devkmsg=
> option when they wanna see all messages. Normally, we do add cmdline
> options to the kernel cmdline when debugging, like
>
> debug ignore_loglevel log_buf_len=16M ...

Right, but unlike log_buf_len, devkmsg is a bit close to a "binary" knob:
either all messages or none; it's not like we can say "printk.devkmsg=100
messages per 5 * HZ max".

-ss