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Date: Sat, 6 Sep 2008 20:09:50 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hugh@veritas.com>,
       =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= <zajec5@gmail.com>,
       Alan Jenkins <alan-jenkins@tuffmail.co.uk>,
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       "H. Peter Anvin" <hpa@zytor.com>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Dave Jones <davej@redhat.com>
Subject: Re: [PATCH RFC] x86: check for and defend against BIOS memory
	corruption
Message-ID: <20080906180950.GA18649@elte.hu>
References: <20080829102547.655440bf@lxorguk.ukuu.org.uk> <b170af450808290313x574b4561i3048ffca3e4da197@mail.gmail.com> <Pine.LNX.4.64.0808291120540.8561@blonde.site> <b170af450808290454m2f349ce3w4f400b0df0e105a2@mail.gmail.com> <48B7E6EE.9090901@tuffmail.co.uk> <Pine.LNX.4.64.0808291413260.12571@blonde.site> <b170af450808291039u7d036313x49acdaec079e6213@mail.gmail.com> <b170af450809041242n43a6ef70s47a2e3e068619af0@mail.gmail.com> <Pine.LNX.4.64.0809042056270.3012@blonde.site> <48C06989.6080307@goop.org>
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* Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> > I would prefer you both to use the minimal memmap= solutions for 
> > now; but others may disagree.
> 
> The fact that we're seeing this problem in two completely different 
> systems with different BIOSes and everything else makes me worried 
> that this is quite widespread.  It's only the persistence and 
> diligence of our bug reporters that we managed to work out that 
> they're the same problem.  How many other people are getting strange 
> crashes and haven't managed to correlate it any particular BIOS 
> interaction?  Or just happen to be corrupting memory we don't care 
> about right now, but is only a small code change or link order change 
> away from disaster?

please put this all behind a .config debug option that distros can turn 
on/off. Also, when it's enabled in the .config, there should be another 
.config option that marks it disabled by default but it can be enabled 
via a boot parameter.

Distro debug kernels will most likely enable the .config - even release 
kernels might enable it it, with default off - users can enable the boot 
switch if they suspect something, without having to build a new kernel.

	Ingo