Re: Question to recent xentools3 update

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Thu, Mar 27, 2008 at 02:18:57PM +0100, Christoph Egger wrote:
> 
> 
> Hi!
> 
> In pkgsrc/sysutils/xentools3/patches/patch-di there is a comment,
> which says, reads from raw disk must be sector-aligned.
> 
> a) Why is that?

The raw device pass requests directly to the underlying device, with
only check/adjustements against the partition bounds. Especially it won't
try to do read/modify/write for write requests, or expand the read if it's
not sector-aligned.

> b) Is there a non-raw device w/o this requirement?

The block device doesn't have this restriction. But it has other side effects
(as it goes though the buffer cache), I don't know if it would be suitable
for pygrub ... it's definitively not usaeable for the block device backend,
or for qemu-dm I/O.

-- 
Manuel Bouyer, LIP6, Universite Paris VI.           
Manuel.Bouyer%lip6.fr@localhost
     NetBSD: 26 ans d'experience feront toujours la difference
--