Re: [PATCH] intel-iommu: Synchronize gcmd value with global commandregister

From: Joerg Roedel
Date: Wed Mar 27 2013 - 06:31:28 EST


On Wed, Mar 27, 2013 at 02:02:44PM +0900, Takao Indoh wrote:
> The root cause of this problem is mismatch between iommu->gcmd and
> global command register in the case of kdump. At boot time, initial
> value of iommu->gcmd is zero as I wrote above, but actual global command
> register is *not* zero because some bits like IRE/TE/QIE are already set
> in *first* kernel. Therefore this patch synchronize them to fix this
> problem.

Ok, I understand, but I still don't see why this is a problem. There is
no point for the kdump kernel to preserve hardware state from the
previous kernel. So I think the way it is implemented is correct.


Joerg


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