From mboxrd@z Thu Jan  1 00:00:00 1970
From: Pavel Machek <pavel@ucw.cz>
Subject: Re: [PATCH 0/2][concept RFC] x86: BIOS-save kernel log to disk
 upon panic
Date: Thu, 3 Feb 2011 15:36:45 +0100
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To: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>, "Ahmed S. Darwish" <darwish.07@gmail.com>, "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, X86-ML <x86@kernel.org>, Tony Luck <tony.luck@intel.com>, Dave Jones <davej@redhat.com>, Andrew Morton <akpm@linux-foundation.org>, Randy Dunlap <rdunlap@xenotime.net>, Willy Tarreau <wtarreau@hera.kernel.org>, Willy Tarreau <w@1wt.eu>, Dirk Hohndel <hohndel@infradead.org>, Dirk.Hohndel@intel.com, IDE-ML <linux-ide@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>, Linus Torvalds <torvalds@linux-foundation.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Fr?d?ric Weisbecker <fweisbec@gmail.com>, Borislav Petkov <bp@alien8.de>, Arjan van de Ven <arjan@infradead.org>

Hi!

> > I think the biggest areas of practical concern would be:
> > 
> >  - Can this mechanism ever, under any circumstance corrupt any real
> >    data, destroy the MBR or do other nasties. Can you think of any
> >    additional fail-safe measures where you could _further robustify
> >    the BIOS calls_ to make sure it can never go to the wrong
> >    sector(s)? I really do not want to think of trusting a BIOS to
> >    _write to my disk_.
> 
> It's quite unlikely but I wouldn't say it's completely impossible.
> It's common for ATA controllers to have dual modes of operation - the
> old IDE compatible interface by emulation which is used by BIOS and
> older operating systems and newer interface (ahci) to be used by
> modern OS.  Some need to be explicitly switched and some just need to
> be accessed carefully.  If the controller is accessed by bIOS after
> switched to ahci or commands are in progress via ahci, anything can
> happen.

Could we read the log area, first, verify it contains signature, write
it back?
								Pavel
-- 
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