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.
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