Re: [PATCH] panic.c: export panic_on_oops

Ingo Molnar
2009-10-12T18:24:06Z

* Andrew Morton <akpm@linux-foundation.org> wrote:

> On Mon, 12 Oct 2009 08:36:38 -0700 (PDT) Linus Torvalds <torvalds@linux-foundation.org> wrote:
>
> > I agree with the "save kernel buffer on panic" thing, but I disagree with
> > making it anything new, and hooking into "printk()" or the console
> > subsystem AT ALL. That's just bogus, stupid, and WRONG.
> >
> > What you can do is to just flush the 'log_buf' buffer (or as much of it as
> > you want - the buffer may be a megabyte in size, and maybe you only want
> > to flush the last 8kB or something like that) on oops. And _not_ mix this
> > up with anything else.
>
> What he said. I did it that way in the Digeo kernel back in 2002.
> Worked good.
>
> Doing it via a console is rather weird. It will need core kernel
> changes to do it properly.
>
> Perhaps oops_enter() is a good place to mark the start of the log, and
> flush it within oops_exit().

Simplest would be to do the last 2K in oops_exit()? That gives the oops,
and the history leading up to it. Since the blocking is 2K, the extra
log output is for free.

(unless the oops is larger than 2K - but that is rather rare.)

Ingo