Re: [Qemu-devel] Regression opening read-only cdroms

[Stefano Stabellini]

Anthony Liguori wrote:

> Jamie Lokier wrote:
>>> Indeed.
>>> I have a patch that adds bdrv_set_read_only that set bs->read_only = 1
>>> so that bdrv_open2 can check if the flag is set and act accordingly.
>>> The problem is that in xen we read whether the device should be opened
>>> read only in the VM config file, I don't think the user can specify to
>>> open a drive read-only in qemu.
>>>     
>> What's missing is a "ro" sub-option to "-drive".
>>   
> 
> It only is useful if we can expose that read-only attribute to the 
> guest.  You can't do that consistently with all block devices so the 
> result would be that you'll fail write operations causing a guest to crash.
> 
> This is not friendly to a user who expects that ro would Just Work.
> 

Well, it could Just Work for cdrom.