Re: [PATCH v2 09/11] scsi-disk: allow MODE SELECT block descriptor to set the ROM device block size

[Paolo Bonzini <pbonzini@redhat.com>]

On 4/24/22 18:49, Mark Cave-Ayland wrote:
> Whilst CDROM drives usually have a 2048 byte sector size, older drives have the
> ability to switch between 2048 byte and 512 byte sector sizes by specifying a
> block descriptor in the MODE SELECT command.
> 
> If a MODE SELECT block descriptor is provided, update the scsi-cd device block
> size with the provided value accordingly.
> 
> This allows CDROMs to be used with A/UX whose driver only works with a 512 byte
> sector size.
> 
> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>

Why do this only for MMC?

Paolo

> ---
>   hw/scsi/scsi-disk.c  | 7 +++++++
>   hw/scsi/trace-events | 1 +
>   2 files changed, 8 insertions(+)
> 
> diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
> index 6991493cf4..41ebbe3045 100644
> --- a/hw/scsi/scsi-disk.c
> +++ b/hw/scsi/scsi-disk.c
> @@ -1583,6 +1583,13 @@ static void scsi_disk_emulate_mode_select(SCSIDiskReq *r, uint8_t *inbuf)
>           goto invalid_param;
>       }
>   
> +    /* Allow changing the block size of ROM devices */
> +    if (s->qdev.type == TYPE_ROM && bd_len &&
> +        p[6] != (s->qdev.blocksize >> 8)) {
> +            s->qdev.blocksize = p[6] << 8;
> +            trace_scsi_disk_mode_select_rom_set_blocksize(s->qdev.blocksize);
> +    }
> +
>       len -= bd_len;
>       p += bd_len;
>   
> diff --git a/hw/scsi/trace-events b/hw/scsi/trace-events
> index 25eae9f307..1a021ddae9 100644
> --- a/hw/scsi/trace-events
> +++ b/hw/scsi/trace-events
> @@ -340,6 +340,7 @@ scsi_disk_dma_command_WRITE(const char *cmd, uint64_t lba, int len) "Write %s(se
>   scsi_disk_new_request(uint32_t lun, uint32_t tag, const char *line) "Command: lun=%d tag=0x%x data=%s"
>   scsi_disk_aio_sgio_command(uint32_t tag, uint8_t cmd, uint64_t lba, int len, uint32_t timeout) "disk aio sgio: tag=0x%x cmd=0x%x (sector %" PRId64 ", count %d) timeout=%u"
>   scsi_disk_mode_select_page_truncated(int page, int len, int page_len) "page %d expected length %d but received length %d"
> +scsi_disk_mode_select_rom_set_blocksize(int blocksize) "set ROM block size to %d"
>   
>   # scsi-generic.c
>   scsi_generic_command_complete_noio(void *req, uint32_t tag, int statuc) "Command complete %p tag=0x%x status=%d"