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Date: Wed, 09 Aug 2006 14:41:13 +0200
From: Artur Skawina <art_k@o2.pl>
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Subject: [Qemu-devel] qemu -cdrom /dev/cdrom opens the cdrom for RW and
 fails w/ RO devices (linux)
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To: qemu-devel@nongnu.org, Fabrice Bellard <fabrice@bellard.org>

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recently (probably since the AIO code went in) qemu opens the cdrom device like this:

> open("/dev/cdrom", O_RDWR|O_LARGEFILE)    = -1 EROFS (Read-only file system)

which obviously fails and qemu quits w/ an error message about being unable to access the cdrom.
Patch below makes a RO -cdrom device work (but doesn't necessarily address the real bug - should qemu really be opening cdrom devices for rw?)

artur



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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;
     }

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