[PATCH v2] scsi-disk: support setting CD-ROM block size via device options

[John Millikin]

SunOS expects CD-ROM devices to have a block size of 512, and will
fail to mount or install using QEMU's default block size of 2048.

When initializing the SCSI device, allow the `physical_block_size'
block device option to override the default block size.

Signed-off-by: John Millikin <john@john-millikin.com>
---
 hw/scsi/scsi-disk.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

This is the same diff as sent to qemu-devel@ about a week ago. That
first email seems to have been eaten by a grue, but replying to it
worked, so maybe the grue is gone now.

See https://gitlab.com/qemu-project/qemu/-/issues/1127 for some
related discussion about SunOS CD-ROM compatibility.

diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index f5cdb9ad4b..acdf8dc05c 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -2533,6 +2533,7 @@ static void scsi_cd_realize(SCSIDevice *dev, Error **errp)
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, dev);
     AioContext *ctx;
     int ret;
+    uint32_t blocksize = 2048;
 
     if (!dev->conf.blk) {
         /* Anonymous BlockBackend for an empty drive. As we put it into
@@ -2542,9 +2543,13 @@ static void scsi_cd_realize(SCSIDevice *dev, Error 
**errp)
         assert(ret == 0);
     }
 
+    if (dev->conf.physical_block_size != 0) {
+        blocksize = dev->conf.physical_block_size;
+    }
+
     ctx = blk_get_aio_context(dev->conf.blk);
     aio_context_acquire(ctx);
-    s->qdev.blocksize = 2048;
+    s->qdev.blocksize = blocksize;
     s->qdev.type = TYPE_ROM;
     s->features |= 1 << SCSI_DISK_F_REMOVABLE;
     if (!s->product) {
-- 
2.25.1