Re: [Xen-devel] Re: [PATCH][VTD] force boot to fail if interrupt remapping cannot be enabled when iommu=force

[Joanna Rutkowska <joanna@xxxxxxxxxxxxxxxxxxxxxx>]

On 04/28/11 19:05, Keir Fraser wrote:
> On 28/04/2011 00:42, "Kay, Allen M" <allen.m.kay@xxxxxxxxx> wrote:
> 
>> Force Xen boot to fail if interrupt remapping fails to enable and the
>> following are true: iommu=force is set as xen boot parameter, VT-d engine HW
>> is interrupt remapping capable, DMAR_INTR_REMAP bit is set in DMAR flags.
>> This forces iommu=force boot instances has interrupt remapping enabled if HW
>> and BIOS supports it.
> 
> If HW and BIOS support it, why would it fail to be enabled? This doesn't
> look like a particularly useful panic() path. If interrupt remapping is so
> important, perhaps iommu=force should unconditionally require it, and panic
> in its absence regardless of platform features?

Indeed, seems to me like a desired behavior.

j.

> As it is, this looks like a
> panic that is never realistically going to trigger.
> 
>  -- Keir
> 
>> Signed-off-by: Allen Kay <allen.m.kay@xxxxxxxxx>
> 
> 
> 
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