Re: [Intel-gfx] [PATCH] iommu: export no_iommu and dmar_disabled symbols

From: Keith Packard
Date: Wed Nov 23 2011 - 15:48:17 EST


On Wed, 23 Nov 2011 20:36:00 +0000, David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:

> This is horrid. In the general case, drivers have no business knowing
> this. We need to properly identify what is wrong with this hardware, and
> put in a quirk for it â perhaps refusing to enable the IOMMU at all on
> the broken chipsets.

That'd be fine with me, right now we're disabling RC6 and semaphores --
semaphores aren't all that important, although they do improve
performance a bit. RC6 is important, saving a huge amount of power.

I'd also be OK with requiring special options to enable DMAR and having
that also disable RC6/semaphores, if you'd rather expose that. In either
case, we need something that works and avoids hanging machines.

--
keith.packard@xxxxxxxxx

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