Re: [Qemu-devel] [Xen-devel] [PATCH v2] xen: fix qdisk BLKIF_OP_DISCARD for 32/64 word size mix

[Jan Beulich]

>>> On 17.06.16 at 11:31, <address@hidden> wrote:
> On 17/06/16 11:26, Jan Beulich wrote:
>>>>> On 17.06.16 at 11:14, <address@hidden> wrote:
>>> In case the word size of the domU and qemu running the qdisk backend
>>> differ BLKIF_OP_DISCARD will not work reliably, as the request
>>> structure in the ring have different layouts for different word size.
>>>
>>> Correct this by copying the request structure in case of different
>>> word size element by element in the BLKIF_OP_DISCARD case, too.
>>>
>>> The easiest way to achieve this is to resync hw/block/xen_blkif.h with
>>> its original source from the Linux kernel.
>>>
>>> Signed-off-by: Juergen Gross <address@hidden>
>>> ---
>>> V2: resync with Linux kernel version of hw/block/xen_blkif.h as
>>>     suggested by Paul Durrant
>> 
>> Oh, I didn't realize he suggested syncing with the Linux variant.
>> Why not with the canonical one? I have to admit that I particularly
>> dislike Linux'es strange union-izng, mainly because of it requiring
>> this myriad of __attribute__((__packed__)).
> 
> What would be gained by syncing with the canonical one? The part to be
> modified is available in the Linux variant only.

In, as said, a rather disgusting (in my opinion) way. I'm no the
maintainer anyway, so you don't have to convince me.

Jan