Re: [Qemu-devel] [PATCH] block.c: fix real cdrom detection

[Programmingkid]

On Jun 25, 2015, at 2:01 PM, Peter Maydell wrote:

> On 25 June 2015 at 18:56, Programmingkid <address@hidden> wrote:
>> Nice to hear from you again Laurent. The only way a solution in
>> hdev_open() would work is if it could prevent find_image_format()
>> from executing. Otherwise find_image_format() would just quit QEMU
>> with an error.
> 
> The question you should be asking is "what is Linux doing for
> raw CDROM devices that is different, such that it works there
> but doesn't work on OSX?".
> 
> It would also be helpful to know which is the case that doesn't
> work. Does QEMU fail in all cases, or only if the cdrom drive is
> empty, or only if there's a disk in the drive?

QEMU fails if the cdrom is specified "-cdrom /dev/cdrom", and there is no cd in 
the drive. 

QEMU also fails with a real cdrom in the drive. 

> 
> My initial suspicion is that we need OSX support in raw-posix.c
> for handling the host CDROM specially -- note that Linux and
> FreeBSD register a bdrv_host_cdrom with an is_inserted
> function.

The is_inserted function wouldn't make a difference. 

I did follow the execution of QEMU from find_image_format(). When 
bdrv_co_io_em() is called, it returns -22. This is where things appear to start 
to go wrong.