diff -urNp qemu.org/block.c qemu/block.c
--- qemu.org/block.c	2006-08-07 21:36:12.000000000 +0000
+++ qemu/block.c	2006-08-08 13:05:01.000000000 +0000
@@ -332,7 +332,7 @@ int bdrv_open2(BlockDriverState *bs, con
     else
         open_flags = flags & ~(BDRV_O_FILE | BDRV_O_SNAPSHOT);
     ret = drv->bdrv_open(bs, filename, open_flags);
-    if (ret == -EACCES && !(flags & BDRV_O_FILE)) {
+    if ((ret == -EACCES || ret == -EROFS) && !(flags & BDRV_O_FILE)) {
         ret = drv->bdrv_open(bs, filename, BDRV_O_RDONLY);
         bs->read_only = 1;
     }