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

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Juergen Gross [mailto:jgross@xxxxxxxx]
> Sent: 16 June 2016 13:19
> To: Paul Durrant; qemu-devel@xxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxx
> Cc: Anthony Perard; sstabellini@xxxxxxxxxx; kraxel@xxxxxxxxxx
> Subject: Re: [Xen-devel] [PATCH] xen: fix qdisk BLKIF_OP_DISCARD for 32/64
> word size mix
> 
> On 16/06/16 13:24, Paul Durrant wrote:
> >> -----Original Message-----
> >> From: Xen-devel [mailto:xen-devel-bounces@xxxxxxxxxxxxx] On Behalf Of
> >> Juergen Gross
> >> Sent: 16 June 2016 11:02
> >> To: qemu-devel@xxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxx
> >> Cc: Anthony Perard; Juergen Gross; sstabellini@xxxxxxxxxx;
> >> kraxel@xxxxxxxxxx
> >> Subject: [Xen-devel] [PATCH] xen: fix qdisk BLKIF_OP_DISCARD for 32/64
> >> word size mix
> >>
> >> 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.
> >>
> >> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> >
> > Would it not be better to re-import the canonical blkif header as a whole
> rather than cherry-picking like this? You'd need to post-process to maintain
> style and possibly change some names for compatibility etc. but probably
> nothing beyond what indent and a simple [s]ed script can do.
> > I did broadly the same thing to re-import the netif header into Linux
> recently.
> 
> It's a little bit more than indent/sed, but nothing really scary.
> 
> I'll do it.
>

Cool. The nice thing about bringing the header up-to-date is it pulls in all 
the newer comments and explanations too :-)
 
  Paul

> 
> Juergen
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