Re: Question to recent xentools3 update

[Juergen Hannken-Illjes <hannken%eis.cs.tu-bs.de@localhost>]

On Thu, Mar 27, 2008 at 03:51:51PM +0100, Manuel Bouyer wrote:
> 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.

As of -current the block device allows only ONE open, therefore it is not
usable by pygrub.

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

-- 
Juergen Hannken-Illjes - hannken%eis.cs.tu-bs.de@localhost - TU Braunschweig 
(Germany)