Re: [PATCH] megaraid_sas: Enable shared tag map

Hannes Reinecke
2014-10-02T09:50:44Z

On 10/02/2014 11:19 AM, Christoph Hellwig wrote:
> On Thu, Oct 02, 2014 at 08:51:20AM +0200, Hannes Reinecke wrote:
>>
>> I'm afraid it's not _that_ easy.
>> SCSI-II tagged queueing has some specific tag values:
>>
>> #define SIMPLE_QUEUE_TAG 0x20
>> #define HEAD_OF_QUEUE_TAG 0x21
>> #define ORDERED_QUEUE_TAG 0x22
>
> These are not tag values. These are message codes set in the first byte
> of the Queue tag message, the second byte is the actual tag.
>
>> The recommendation here is to use 'scmd->request->tag' whenever
>> you want to get to the tag number, and 'scmd->tag' if you have to
>> play around with SCSI-II TCQ.
>> But if not I would strongly advise to leave 'scmd->tag' alone.
>
> Or kill off scmd->tag.. Let's see how feasible that is.
>
I'm about to.
(See my last two patches).
There are now two instances left:
NCR5380 (and derived LLDDs) and fnic.
For some weird reasons fnic decided to duplicate blk-tag
functionality. Looking into it.

And NCR5380 tag support can be safely ignored, it never worked anyway.

Cheers,

Hannes
--
Dr. Hannes Reinecke zSeries & Storage
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SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
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