linux-kernel - Re: [PATCH 0/3] Boot IRQ quirks for Broadcom and AMD/ATI

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Date:	Mon, 14 Jul 2008 09:24:58 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Olaf Dabrunz <od@...e.de>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Jon Masters <jonathan@...masters.org>,
	Stefan Assmann <sassmann@...e.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Ihno Krumreich <ihno@...e.de>,
	Sven Dietrich <sdietrich@...e.de>,
	Daniel Gollub <dgollub@...e.de>,
	Felix Foerster <ffoerster@...e.de>
Subject: Re: [PATCH 0/3] Boot IRQ quirks for Broadcom and AMD/ATI

On Sunday, July 13, 2008 2:01 pm Ingo Molnar wrote:
> * Olaf Dabrunz <od@...e.de> wrote:
> > This is against linux-2.6-tip, branch pci-ioapic-boot-irq-quirks.
> >
> > The corrected versions of the Broadcom and AMD/ATI boot IRQ quirks,
> > and a patch that uses DECLARE_PCI_FIXUP_FINAL instead of *_EARLY, and
> > adds *_RESUME.
> >
> > The AMD/ATI SB700S does not need a quirk. The boot IRQs here are
> > active even when the IO-APIC lines are not masked. So even for
> > traditional IRQ handling that does not use masking, the boot IRQs need
> > to be disabled by the BIOS. If there are actual cases of BIOSes that
> > do not disable these boot IRQs in APIC mode, we could consider
> > including an SB700S patch. But I doubt this will be needed, as this
> > problem would quickly surface during testing with any general-purpose
> > OS.
> >
> > The quirk for the AMD 8131 and AMD 8132 takes identical action as an
> > existing quirk for the AMD 8131 rev. A0 and B0. The existing quirk is
> > due to an AMD erratum to fix IO-APIC mode. Our patch now deletes the
> > older quirk and adds a comment to the new one that describes the two
> > purposes of the quirk.
>
> applied to tip/x86/pci-ioapic-boot-irq-quirks, thanks Olaf.
>
> Jesse, what do you think about this topic? We are keeping it separate
> for the time being. They are not particularly pretty, but being able to
> mask/unmask irqs (without generating those legacy IRQs and creating an
> IRQ storm) is essential to -rt.

See my other reply; the branch looks good.  I agree that making sure -rt can 
work is an important feature.  My only concern is that this is touching so 
much hardware specific code that *something* is likely to break.  But as long 
as Olaf & co. can help track down any issues, I'm ok with it.

Thanks,
Jesse
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