On Thu, Jun 25, 2015 at 11:11:24AM -0400, Programmingkid wrote: > On Jun 25, 2015, at 9:31 AM, Stefan Hajnoczi wrote: > > On Tue, Jun 23, 2015 at 02:26:51PM -0400, Programmingkid wrote: > >> On Jun 23, 2015, at 2:06 PM, John Snow wrote: > >>> So what's the issue that this patch attempts to fix and how did you > >>> determine that the fix was needed here? It doesn't look like it respects > >>> proper abstraction at a glance. > >> > >> Without the patch, QEMU would just quit when the "-cdrom /dev/cdrom" > >> option is given. > > > > Why does it quit? > > Because of a bug. This is what it prints: "Could not read image for > determining its format: Invalid argument".
The bdrv_pread() failure is what need you need to investigate. In the other sub-thread there have been hints about adding CD-ROM passthrough support on Mac OS X by filling in the missing parts in block/raw-posix.c. That should help you get to the bottom of the problem. > This message seems to indicate that QEMU thinks the real cdrom drive is an > image file. If the -drive format= option is not given, QEMU will try to detect the image format. That's the purpose of the find_image_format() function. QEMU does not make a distinction between image files and block devices because there are valid use cases where a block device uses an image format. For example, a disk or partition can contain qcow2 data (there is no partition table or file system, just qcow2).
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