Messages in this thread | | | Date | Tue, 24 May 2011 00:45:47 +0100 | From | Daniel Haid <> | Subject | Re: Question about iommu on x86 64 and ra deon driver. |
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> There had to be more than 'Map around memory hole'? Was it called > GART or IOMMU? I do not think that there was "IOMMU" or "GART" written there, but I do not think that the mainboard in question has an IOMMU (Am I correct that it would be a feature of the mainboard while the AMD GART is a feature of the CPU?). I will look again as soon as I have physical access to the system.
> The problem you are hitting (I think) is that the AMD GART poor-man > IOMMU is turned off > and the SWIOTLB is used instead. If you would like some technical > details, take a look at: > > http://lists.freedesktop.org/archives/dri-devel/2011-January/006885.html > (the point #2 is what you are hitting).
You are correct. In all the cases where the radeon card does not work I see that SWIOTLB has been enabled in the kernel log.
So this is a bug? I suppose that all hardware should be working with SWIOTLB? Will a patch that fixes this somewhen be included? (The bug where your link points to was closed with WONTFIX)
> Not sure why the AMD GART IOMMU gets disabled on VIA chipsets. You > might > want to use 'git gui blame arch/x86/kernel/early-quirks.c' and look > at the code in question to figure that out. > Well, if everything works.... but you might just want to use > the git gui blame to take a look at the back-story of why the quirk > was added.
Unfortunately I am getting crashes with "iommu=allowed". I will look at git blame.
Thank you for your answers.
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