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

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Fri, May 13, 2016 at 02:36:18PM -0600, Jim Fehlig wrote:
> 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@xxxxxxxx>
> >> 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 :-).
> 

Yes, it's on my radar. I wanted to give some time for other people to
look at it.

Now two weeks has passed, I've queued it up for committing.

Wei.


> Regards,
> Jim
> 

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