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

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Date:	Mon, 6 Oct 2008 19:54:56 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	"Maciej W. Rozycki" <macro@...ux-mips.org>
Cc:	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)


* Maciej W. Rozycki <macro@...ux-mips.org> wrote:

> On Mon, 6 Oct 2008, Ingo Molnar wrote:
> 
> > i think it was caused by this stream of IO-APIC changes:
> > 
> >  49a66a0: x86: I/O APIC: Always report how the timer has been set up
> >  17c4469: x86: I/O APIC: Include <asm/i8259.h> required by some code
> >  593f4a7: x86: APIC: remove apic_write_around(); use alternatives
> >  ce8b06b: x86: I/O APIC: remove an IRQ2-mask hack
> >  af17478: x86: I/O APIC: Never configure IRQ2
> >  c88ac1d: x86: L-APIC: Always fully configure IRQ0
> >  1baea6e: x86: L-APIC: Set IRQ0 as edge-triggered
> > 
> > Rafael/Maciej, which of these is causing it? ce8b06b ("x86: I/O APIC: 
> > remove an IRQ2-mask hack")?
> 
>  None of the above.  This:
> 
> 691874f: x86: I/O APIC: timer through 8259A second-chance
> 
> This change has fixed a problem with the timer for a lot of systems 
> and permitted the removal of a bunch of horrible hacks we used to have 
> in our I/O-APIC/timer code, including a command-line override 
> parameter, needed so that some systems would boot at all.
> 
>  This single instance of a piece of some HP gear being twisted beyond 
> belief is IMO a minor annoyance and price to pay compared to the gain.  
> Please note that apart from the DSDT being buggy on this machine, it 
> has an incorrect IRQ 0 override in the ACPI table pointing to the pin 
> #2 of the I/O APIC, which is in fact routed to the output of the 
> master 8259A.  Additionally the pin #0 of the I/O APIC which is indeed 
> routed to the output of the 8254 does not receive any interrupts, 
> presumably because of some misconfiguration during BIOS 
> initialisation.  So in fact this machine suffers from three 
> configuration problems at once of which all add up to the end result 
> we can observe.

okay. Perhaps we can find some better DMI filter for affected 
HP+AMD+Turion laptops - how futile that might be. No chance to have some 
automated non-DMI check?

	Ingo
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