Re: [Qemu-devel] buffer alignment for block backends

[Anthony Liguori]

Gerd Hoffmann wrote:
> > > The xen block protocol can handle unaligned requests just fine.
> >
> > Not completely arbitrarily aligned requests. They need to be
> > sector-aligned.
>
> Agreed.  Sector-alignment you have anyway, thats why I didn't wrote 
> that explicitly.

But even sector-alignment is not guaranteed for the buffers in the 
bdrv_* API.

You can implement a backend that just implements aio_read/aio_write and 
you'll always get sector-aligned offsets, but the actual data buffers 
may have any alignment.

Regards,

Anthony Liguori

> cheers,
>   Gerd