Re: [PATCH 4/5] esp: revert 75ef849696 "esp: correctly fill bus id with requested lun"

[Mark Cave-Ayland]

On 11/06/2021 12:38, Paolo Bonzini wrote:

> On 09/06/21 17:31, Mark Cave-Ayland wrote:
> > Due to the absence of the IDENTIFY byte in the S case I'm guessing from the patch 
> > that the LUN is in encoded in buf[1] (the top bits being "Reserved" according to my 
> > copy of the specification).
>
> They used to be the LUN many years ago.

Got it :)

> >   static void s_without_satn_pdma_cb(ESPState *s)
> >   {
> > +    uint8_t busid;
> > +
> >       if (!esp_get_tc(s) && !fifo8_is_empty(&s->cmdfifo)) {
> >           s->cmdfifo_cdb_offset = 0;
> >           s->do_cmd = 0;
> > -        do_busid_cmd(s, 0);
> > +        busid = s->cmdfifo.data[1] >> 5;
> > +        do_busid_cmd(s, busid);
> >       }
> >   }
>
> Considering how obsolete the LUN-in-CDB case is (and now that I actually understand 
> that the first byte is a message-phase byte), it is probably be more correct to keep 
> the previous busid: with no message phase, the previously-selected LUN would be 
> addressed.  I can send a patch for this, but it's orthogonal to this one so I queued 
> it as well.

That was going to be my next question - how do you determine the LUN if there is no 
message phase byte? But that makes sense to me. I don't think that I have a 
LUN-in-CDB example in my set of ESP test images, but I'm happy to run them against 
your patch and make sure there are no regressions.


ATB,

Mark.