linux-kernel - Re: [PATCH] x86 ACPI: Blacklist two HP machines with buggy BIOSes (Re: 2.6.27-rc8+

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Date:	Tue, 7 Oct 2008 01:10:02 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	"Maciej W. Rozycki" <macro@...ux-mips.org>
Cc:	Andi Kleen <andi@...stfloor.org>, Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Len Brown <lenb@...nel.org>,
	Jason Vas Dias <jason.vas.dias@...il.com>
Subject: Re: [PATCH] x86 ACPI: Blacklist two HP machines with buggy BIOSes (Re: 2.6.27-rc8+ - first impressions)

On Mon, Oct 06, 2008 at 10:39:25PM +0100, Maciej W. Rozycki wrote:
> On Mon, 6 Oct 2008, Andi Kleen wrote:
> 
> > The real reason is actually a workaround in the BIOS for problems
> > in the older Linux code that caused duplicated timer interrupts. The
> > old Linux would fall into "enable both IO-APIC and 8259" fallback mode
> > and the resulted in duplicated timer events, which made everything unhappy.
> > They instead configured the northbridge in a way that one of the inputs
> > is ignored.
> 
>  Hmm, working around Linux problems in the BIOS is a new and truly odd 
> concept to me. 

Except perhaps for the cheapest consumer parts and many laptops Linux is 
definitely on the radar now for many BIOS developers.

> It's not that we are unresponsive or do not take 
> responsibility for our bugs, is it?

These workarounds are not for mainline kernels but for specific
distribution releases (as in "fixes SLES/RHEL x.y" instead of 
"fixes 2.6.xy")

Even when the distributors update their kernels the old releases
do not go away are still used and the workarounds get in.

> > You won't be able to DMI list it, that workaround is widely used
> > in lots of different systems.
> 
>  Well, perhaps, but the thermal trip point phenomenon seems unique to this 
> family of systems.  The other aspects of the problem do not really matter 
> anymore as we seem to have addressed them robustly enough now.

When you need DMI entries you clearly haven't.

-Andi

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