David, Joerg, I plan to merge this patch set with 3.17 stable kernel, and split this patch set into two : 1. The core part, including the changed functions, like [Patch 4/8], [Patch 8/8]. 2. For the formatting issues, like [Patch 1/8],[Patch 3/8], including the changes for code formations, creation of new files intel-iommu-kdump.c, intel-iommu-private.h. I believe this will make the patch set more clear to read and understand. What are your suggestions? Thanks Zhenhua On 07/12/2014 12:27 AM, Jerry Hoemann wrote: > On Wed, Jul 02, 2014 at 03:32:59PM +0200, Joerg Roedel wrote: >> Hi David, >> >> On Wed, Apr 30, 2014 at 11:49:33AM +0100, David Woodhouse wrote: >>> There could be all kinds of existing mappings in the DMA page tables, >>> and I'm not sure it's safe to preserve them. What prevents the crashdump >>> kernel from trying to use any of the physical pages which are >>> accessible, and which could thus be corrupted by stray DMA? >>> >>> In fact, the old kernel could even have set up 1:1 passthrough mappings >>> for some devices, which would then be able to DMA *anywhere*. Surely we >>> need to prevent that? >> >> Ideally we would prevent that, yes. But the problem is that a failed DMA >> transaction might put the device into an unrecoverable state. Usually >> any in-flight DMA transactions should only target buffers set up by the >> previous kernel and not corrupt any data. >> >>> After the last round of this patchset, we discussed a potential >>> improvement where you point every virtual bus address at the *same* >>> physical scratch page. >> >> That is a solution to prevent the in-flight DMA failures. But what >> happens when there is some in-flight DMA to a disk to write some inodes >> or a new superblock. Then this scratch address-space may cause >> filesystem corruption at worst. >> >> So with this in mind I would prefer initially taking over the >> page-tables from the old kernel before the device drivers re-initialize >> the devices. >> >> >> Joerg > > David, Joerg, > > What do you think here? Do you want me to update the patch set for 3.17? > > Jerry >
