On 05/12/2015 04:17 PM, Dave Young wrote: > On 05/11/15 at 05:52pm, Li, Zhen-Hua wrote: >> Add context entry functions needed for kdump. >> +/* >> + * Fix Crashdump failure caused by leftover DMA through a hardware IOMMU >> + * >> + * Fixes the crashdump kernel to deal with an active iommu and legacy >> + * DMA from the (old) panicked kernel in a manner similar to how legacy >> + * DMA is handled when no hardware iommu was in use by the old kernel -- >> + * allow the legacy DMA to continue into its current buffers. >> + * >> + * In the crashdump kernel, this code: >> + * 1. skips disabling the IOMMU's translating. >> + * 2. Do not re-enable IOMMU's translating. >> + * 3. In kdump kernel, use the old root entry table. >> + * 4. Allocate pages for new context entry, copy data from old context entries >> + * in the old kernel to the new ones. >> + * >> + * In other kinds of kernel, for example, a kernel started by kexec, >> + * do the same thing as crashdump kernel. >> + */ >> + >> + > > Above comments should come along with the code changes instead of putting it > in this patch. > > BTW, there's one more blank line at the end.. Code change is in 00/10, the cover letter. And the blank does not matter, I checked the patch with scripts/checkpatch.pl, no warnings, no errors.
