[SeaBIOS] [PATCH] scsi: do not send MODE SENSE except to QEMU disks

[Dave Frodin]

Paolo,
I tested your patch.
It works with all 14 USB thumbdrives and with a USB-to-SATA
adapter we dug up.

Dave

----- Original Message -----
> From: "Paolo Bonzini" <pbonzini at redhat.com>
> To: seabios at seabios.org
> Cc: "Dave Frodin" <dave at camp.se-eng.com>
> Sent: Monday, March 5, 2012 4:29:12 AM
> Subject: [PATCH] scsi: do not send MODE SENSE except to QEMU disks
> 
> This is the simplest way to avoid breaking boot on USB sticks that
> stall when asked for the MODE SENSE page 4.  Some old sticks do
> not support the MODE SENSE command at all and just return a
> "medium may have changed" unit attention condition when SeaBIOS
> sends it!
> 
> Reported-by: Dave Frodin <dave at camp.se-eng.com>
> Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
> ---
>  src/blockcmd.c |   36 +++++++++++++++++++++++-------------
>  1 files changed, 23 insertions(+), 13 deletions(-)
> 
> diff --git a/src/blockcmd.c b/src/blockcmd.c
> index 2769573..b4a1e37 100644
> --- a/src/blockcmd.c
> +++ b/src/blockcmd.c
> @@ -139,19 +139,29 @@ scsi_init_drive(struct drive_s *drive, const
> char *s, int prio)
>      dprintf(1, "%s blksize=%d sectors=%d\n"
>              , s, drive->blksize, (unsigned)drive->sectors);
>  
> -    struct cdbres_mode_sense_geom geomdata;
> -    ret = cdb_mode_sense_geom(&dop, &geomdata);
> -    if (ret == 0) {
> -        u32 cylinders;
> -        cylinders = geomdata.cyl[0] << 16;
> -        cylinders |= geomdata.cyl[1] << 8;
> -        cylinders |= geomdata.cyl[2];
> -        if (cylinders && geomdata.heads &&
> -            drive->sectors <= 0xFFFFFFFFULL &&
> -            ((u32)drive->sectors % (geomdata.heads * cylinders) ==
> 0)) {
> -            drive->pchs.cylinders = cylinders;
> -            drive->pchs.heads = geomdata.heads;
> -            drive->pchs.spt = (u32)drive->sectors / (geomdata.heads
> * cylinders);
> +    // We do not recover from USB stalls, so try to be safe and
> avoid
> +    // sending the command if the (obsolete, but still provided by
> QEMU)
> +    // fixed disk geometry page may not be supported.
> +    //
> +    // We could also send the command only to small disks (e.g.
> <504MiB)
> +    // but some old USB keys only support a very small subset of
> SCSI which
> +    // does not even include the MODE SENSE command!
> +    //
> +    if (! CONFIG_COREBOOT && memcmp(vendor, "QEMU    ", 8) == 0) {
> +        struct cdbres_mode_sense_geom geomdata;
> +        ret = cdb_mode_sense_geom(&dop, &geomdata);
> +        if (ret == 0) {
> +            u32 cylinders;
> +            cylinders = geomdata.cyl[0] << 16;
> +            cylinders |= geomdata.cyl[1] << 8;
> +            cylinders |= geomdata.cyl[2];
> +            if (cylinders && geomdata.heads &&
> +                drive->sectors <= 0xFFFFFFFFULL &&
> +                ((u32)drive->sectors % (geomdata.heads * cylinders)
> == 0)) {
> +                drive->pchs.cylinders = cylinders;
> +                drive->pchs.heads = geomdata.heads;
> +                drive->pchs.spt = (u32)drive->sectors /
> (geomdata.heads * cylinders);
> +            }
>          }
>      }
>  
> --
> 1.7.7.6
> 
>