Re: [Qemu-devel] [PATCH v3 for-2.9?] virtio: fix vring_align() on 64-bit windows

[Andrew Baumann]

> From: Eric Blake [mailto:address@hidden
> Sent: Tuesday, 28 March 2017 11:52
> 
> On 03/28/2017 01:38 PM, Stefan Weil wrote:
> > Am 25.03.2017 um 00:19 schrieb Andrew Baumann:
> >> long is 32-bits on 64-bit windows, which caused the top half of the
> >> address to be truncated; this patch changes it to use the
> >> QEMU_ALIGN_UP macro which does not suffer the same problem
> >>
> >> Signed-off-by: Andrew Baumann <address@hidden>
> >> Reviewed-by: Eric Blake <address@hidden>
> >> ---
> 
> > Eric added "for-2.9" to the subject line of v2, but now it was
> > missing again for v3.
> >
> > Is this needed for 2.9?
> 
> Yes, it's a correctness bug that avoids miscompilation on 64-bit targets
> where long is 32 bits (which, at the moment, is really just Windows).

I agree, this should be in 2.9. I dropped the tag by accident.

> > I wonder why I never before noticed
> > a problem or got a bug report for this issue.
> 
> Probably because so few people are testing on native Windows, and it
> doesn't affect other platforms.

In addition to that, you only notice it on virtio devices mapped above the 
32-bit limit...

Andrew