On 11/01/2011 05:34 PM, David Woodhouse wrote: > On Tue, 2011-11-01 at 17:19 +0800, Dave Young wrote: >> kdump kernel sometimes will get DMAR faults which >> is caused by random in-flight dma from 1st kernel >> >> Here make the identity_mapping as default for this case > > So you want to *allow* the random in-flight DMA? And with an identity > mapping it's really going to random addresses, since it'll be > untranslated and won't even go to the physical addresses which it was > originally intended for? > > This seems entirely broken to me. > > If there is "random in-flight dma" from the first kernel, the correct > thing to do is *block* it. Which is what we do. > This patch works for me for several cases. For kdump It can be seen a workaround. But yes blocking the 1st kernel dma is ideal. Glad to hear that you are working on this. -- Thanks Dave
