Re: [PATCH v11 02/10] iommu/vt-d: Items required for kdump

["Li, ZhenHua" <zhen-hual@hp.com>]

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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