Add Tom to CC list. On 10/15/2014 04:10 PM, Li, ZhenHua wrote: > 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 >> >
