Re: 32-byte CDB support in Libsas?

James Bottomley
2013-05-07T20:06:50Z

On Tue, 2013-05-07 at 12:46 -0700, Kamaljit Singh wrote:
> James, Jack,
>
> Thanks for your responses.
>
> > I don't understand the question ... it should just work; is it
> broken?
> sas_create_task() only copies 16 bytes to the sas_ssp_task struct’s
> cdb field, which itself is a 16 byte wide array. So it looks like
> sas_queuecommand() doesn’t support a 32-byte cdb.

Hm, it does it as a bare 16 instead of SCSI_MAX_CDB which is probably
how it got missed in the long command conversion.

> > It's easy to add that, define cdb 32 to ssp_task and modify
> sas_queuecommand, and lldd to pass it to fw
> Yes, that’s exactly what I’ve designed it as, i.e. in my lldd’s
> queuecommand function. At the moment I only need this function for
> 32-byte cdb support. But if there are plans to add that to libsas
> then I’d prefer to use sas_queuecommand rather than having to do
> manual merges from future libsas fixes/updates.

I wouldn't do it that way. Since everything has to form a command IU
anyway by copying, I'd just make sas_ssp->cdb a pointer to the actual
command instead of an array of the command; if it points to the
scsi_cmnd, then it has access to cmd_len as well. That way no copying
and no problem when anyone wants longer commands. There should probably
also be a macro to populate the command IU since the format of CDB > 16
is different.

James

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