Re: [PATCH 2/2] iommu: dmar -- reserve mmio space used by IOMMU
On Wed, 2012-06-06 at 10:16 +0200, Ingo Molnar wrote: So basically the patch-set is fine as-is, we just want a sufficiently nasty sounding warning message about the BIOS bug, No. The other change that's required is that the warning and the workaround need to trigger even when IOMMU support isn't built into the kernel. This BIOS bug can bite you even when you aren't *using* the IOMMU. If we could integrate Coreboot into the kernel and could build a bzImage that one could write into the BIOS flash image and thus have an updated and functional BIOS, that would be awesome. People *have* used the kernel as a Coreboot payload, but it's not really the best solution. For anything but deeply embedded devices, you probably do want a real firmware of some kind (like Tianocore). The point in having hardware which is fully supported by Coreboot is that it gives you the choice. You *can* do the above, or more sensibly you can use it to deploy an up-to-date and working Tianocore without the type of bugs that we're discussing here. Or at least without the ones which offend *you*. -- dwmw2 smime.p7s Description: S/MIME cryptographic signature ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH 2/2] iommu: dmar -- reserve mmio space used by IOMMU
On Wed, 2012-06-06 at 10:29 +0200, Ingo Molnar wrote: So for all practical purposes we get 99% of the warning power without going into chicken-and-egg problems like how do we determine that there's an IOMMU area there if there's no IOMMU aware code in the kernel, right? That's not a chicken-and-egg problem. It's hardly difficult to see the DMAR ACPI table and take a *basic* look at the DRHD entries. You don't even need to fully parse it. Doing it even without *ACPI* in your kernel would be a different matter :) -- dwmw2 smime.p7s Description: S/MIME cryptographic signature ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH 2/2] iommu: dmar -- reserve mmio space used by IOMMU
* David Woodhouse (dw...@infradead.org) wrote: On Wed, 2012-06-06 at 10:29 +0200, Ingo Molnar wrote: So for all practical purposes we get 99% of the warning power without going into chicken-and-egg problems like how do we determine that there's an IOMMU area there if there's no IOMMU aware code in the kernel, right? That's not a chicken-and-egg problem. It's hardly difficult to see the DMAR ACPI table and take a *basic* look at the DRHD entries. You don't even need to fully parse it. I had the same impression as Ingo. Patch is basically good as is (fixing most of the problem), and could be augmented later to close the final gap (when no IOMMU code). While parsing the DMAR table is trivial, what are you recommending to use to inform if the region is not properly reserved? thanks, -chris ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
