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

[Mark Cave-Ayland]

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>
---
 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"
-- 
2.20.1