Re: [PATCH v2 07/11] scsi-disk: allow truncated MODE SELECT requests

[Mark Cave-Ayland]

On 26/05/2022 13:06, Paolo Bonzini wrote:

> On 4/24/22 18:49, Mark Cave-Ayland wrote:
> > According to [1] this truncated request is accepted on real hardware whereas in
> > QEMU it generates an INVALID_PARAM_LEN sense code which causes A/UX to get stuck
> > in a loop retrying the command in an attempt to succeed.
>
> That's for MODE SENSE, not MODE SELECT.
>
> Truncated MODE SELECT is a bit more iffy, so I'd rather have a quirk for this 
> as well.

Okay let me double-check this again to confirm whether the issue is with MODE SENSE, 
MODE SELECT or both. Adding a quirk to control the behaviour is fairly easy to do.

> Paolo
>
> > Alter the mode page request length check so that truncated requests are allowed
> > as per real hardware, adding a trace event to enable the condition to be 
> > detected.
> >
> > [1]https://68kmla.org/bb/index.php?threads/scsi2sd-project-anyone-interested.29040/page-7#post-316444 
> >
> >
> > Signed-off-by: Mark Cave-Ayland<mark.cave-ayland@ilande.co.uk>
> > ---
> >   hw/scsi/scsi-disk.c  | 2 +-
> >   hw/scsi/trace-events | 1 +
> >   2 files changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
> > index 71fdf132c1..c657e4f5da 100644
> > --- a/hw/scsi/scsi-disk.c
> > +++ b/hw/scsi/scsi-disk.c
> > @@ -1525,7 +1525,7 @@ static int mode_select_pages(SCSIDiskReq *r, uint8_t *p, int 
> > len, bool change)
> >               goto invalid_param;
> >           }
> >           if (page_len > len) {
> > -            goto invalid_param_len;
> > +            trace_scsi_disk_mode_select_page_truncated(page, page_len, len);
> >           }

ATB,

Mark.