Re: [PATCH V2] libxl: don't add cache mode for qdisk cdrom drives

[Jim Fehlig <jfehlig@suse.com>]

On 05/10/2016 04:06 AM, Stefano Stabellini wrote:
> On Mon, 9 May 2016, Wei Liu wrote:
>> On Thu, Apr 28, 2016 at 03:20:46PM -0600, Jim Fehlig wrote:
>>> qemu commit 91a097e7 forbids specifying cache mode for empty
>>> drives. Attempting to create a domain with an empty qdisk cdrom
>>> drive results in
>>>
>>> qemu-system-x86_64: -drive if=ide,index=1,readonly=on,media=cdrom,
>>>    cache=writeback,id=ide-832: Must specify either driver or file
>>>
>> We need to fix this one way or another.
>>
>>> libxl only allows an empty 'target=' for cdroms. By default, cdroms
>>> are readonly (see the 'access' parameter in xl-disk-configuration.txt)
>>> and forced to readonly by any tools (e.g. xl) using libxlutil's
>>> xlu_disk_parse() function. With cdroms always marked readonly,
>>> explicitly specifying the cache mode for cdrom drives can be dropped.
>>> The drive's 'readonly=on' option can also be set unconditionally.
>>>
>>> Signed-off-by: Jim Fehlig <jfehlig@suse.com>
>> CC Stefano who made the change to use writeback in
>> e9a327bbbcab127625b0917a2780cb3601a81d01 . Also CC Anthony.
>>
>> Ian, Stefano and Anthony, do you have opinion on this patch?
> It looks good to me. We could consider to backport it, given that we
> only have a loose relationship with QEMU and older versions of Xen could
> end up running with newer versions of QEMU.

Wei,

Will this patch make 4.7? It allows empty cdroms with freshly released QEMU 2.6 :-).

Regards,
Jim


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