linux-kernel - Re: [PATCH] panic.c: export panic_on

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20091012113647.454fccc5.akpm@linux-foundation.org>
Date:	Mon, 12 Oct 2009 11:36:47 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Simon Kagstrom <simon.kagstrom@...insight.net>,
	Artem Bityutskiy <dedekind1@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"Koskinen Aaro (Nokia-D/Helsinki)" <aaro.koskinen@...ia.com>,
	linux-mtd <linux-mtd@...ts.infradead.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH] panic.c: export panic_on_oops

On Mon, 12 Oct 2009 20:23:46 +0200 Ingo Molnar <mingo@...e.hu> wrote:

> 
> * Andrew Morton <akpm@...ux-foundation.org> wrote:
> 
> > On Mon, 12 Oct 2009 08:36:38 -0700 (PDT) Linus Torvalds <torvalds@...ux-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.)
> 

Some oops traces can be pretty large.  Perhaps "oops_enter minus 1k up
to oops_exit".

The digeo kernel later got changed to package the oops into a binary
record format for logging to nvram.  iirc that was for space reasons,
and for ease of downstream analysis.

That kernel used to be downloadable but I can't immediately find it. 
Probably not very interesting anyway.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/