Messages in this thread | | | Date | Tue, 21 Apr 2015 09:39:35 +0800 | From | "Li, ZhenHua" <> | Subject | Re: [PATCH v10 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel |
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Hi Dave, I found the old mail: http://lkml.iu.edu/hypermail/linux/kernel/1410.2/03584.html
Please check this and you will find the discussion.
Regards Zhenhua
On 04/15/2015 02:48 PM, Dave Young wrote: > On 04/15/15 at 01:47pm, Li, ZhenHua wrote: >> On 04/15/2015 08:57 AM, Dave Young wrote: >>> Again, I think it is bad to use old page table, below issues need consider: >>> 1) make sure old page table are reliable across crash >>> 2) do not allow writing oldmem after crash >>> >>> Please correct me if I'm wrong, or if above is not doable I think I will vote for >>> resetting pci bus. >>> >>> Thanks >>> Dave >>> >> Hi Dave, >> >> When updating the context tables, we have to write their address to root >> tables, this will cause writing to old mem. >> >> Resetting the pci bus has been discussed, please check this: >> http://lists.infradead.org/pipermail/kexec/2014-October/012752.html >> https://lkml.org/lkml/2014/10/21/890 > > I know one reason to use old pgtable is this looks better because it fixes the > real problem, but it is not a good way if it introduce more problems because of > it have to use oldmem. I will be glad if this is not a problem but I have not > been convinced. > > OTOH, there's many types of iommu, intel, amd, a lot of other types. They need > their own fixes, so it looks not that elegant. > > For pci reset, it is not perfect, but it has another advantage, the patch is > simpler. The problem I see from the old discusssion is, reset bus in 2nd kernel > is acceptable but it does not fix things on sparc platform. AFAIK current reported > problems are intel and amd iommu, at least pci reset stuff does not make it worse. > > Thanks > Dave >
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