Hi Tomo,

FUJITA Tomonori wrote:
quoted text
> On Sat, 8 Sep 2007 13:00:36 +0100
> Christoph Hellwig <hch@infradead.org> wrote:
> 
>> On Sat, Sep 08, 2007 at 07:32:27AM -0400, Jeff Garzik wrote:
>>> FUJITA Tomonori wrote:
>>>> Yeah, iommu code ignores the lld limitations (the problem is that the
>>>> lld limitations are in request_queue and iommu code can't access to
>>>> request_queue). There is no way to tell iommu code about the lld
>>>> limitations.
>>>
>>> This fact very much wants fixing.
>>
>> Absolutely.  Unfortunately everyone wastes their time on creating workarounds
>> instead of fixing the underlying problem.
> 
> Any ideas on how to fix this?
> 
> I chatted to Jens and James on this last week.
> 
> - we could just copies the lld limitations to device structure. it's
> hacky but device structure already has hacky stuff.
> 
> - we could just link device structure to request_queue structure so
> that iommu code can see request_queue structure.
> 
> - we could remove the lld limitations in request_queue strucutre and
> have a new strucutre (something like struct io_restrictions). then
> somehow we could link the new structure with request_queue and device
> strucutres.
> 
I'd prefer the latter. These struct io_restrictions could then be used
by dm (which has it's own version right now) to merge queue capabilities.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
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