Xen devel - Feb 2013 - design questions: blktap & dom0-kernel/Xen binary compatibility

I have two design questions:

a) is there some doc on binary compatibility between dom0-kernels and 
Xen/xen-tools? For example Xen 4.2.1 on my system does not work with 
xenified OpenSuse 12.2 kernel, while it seems to work with vanilla 3.7. 
I am interested in some kind of compatibility matrix having various 
kernels (pvops0, xenified, with versions) on one axis and Xen releases 
on the other axis. Also having some info about reasons for 
breakage-by-design would be helpful.

b) is there some doc/info on what is going on with blktap[1,2,3]? I am 
specifically interested in underlying (design) questions, for example 
why blktap was not migrated to vanilla kernel 3.x?

Regards Andreas

>>> On 04.02.13 at 18:45, Andreas Kinzler <ml-xen-devel@hfp.de>
wrote:
> a) is there some doc on binary compatibility between dom0-kernels and 
> Xen/xen-tools? For example Xen 4.2.1 on my system does not work with 
> xenified OpenSuse 12.2 kernel, while it seems to work with vanilla 3.7. 
> I am interested in some kind of compatibility matrix having various 
> kernels (pvops0, xenified, with versions) on one axis and Xen releases 
> on the other axis. Also having some info about reasons for 
> breakage-by-design would be helpful.
That''s very odd, and clearly unintended (and certainly not the
case for me). But of course you''d need to be more specific to
understand what went wrong here.

Our kernels (unless re-compiled) may not work on older Xen
versions, but they''re certainly intended to work on newer ones.

Jan

> -----Original Message-----
> From: xen-devel-bounces@lists.xen.org [mailto:xen-devel-
> bounces@lists.xen.org] On Behalf Of Andreas Kinzler
> Sent: 04 February 2013 17:46
> To: xen-devel@lists.xen.org
> Subject: [Xen-devel] design questions: blktap & dom0-kernel/Xen binary
> compatibility
> 
> I have two design questions:
> 
> a) is there some doc on binary compatibility between dom0-kernels and
> Xen/xen-tools? For example Xen 4.2.1 on my system does not work with
> xenified OpenSuse 12.2 kernel, while it seems to work with vanilla 3.7.
> I am interested in some kind of compatibility matrix having various
> kernels (pvops0, xenified, with versions) on one axis and Xen releases
> on the other axis. Also having some info about reasons for breakage-by-
> design would be helpful.
> 
> b) is there some doc/info on what is going on with blktap[1,2,3]? I am
> specifically interested in underlying (design) questions, for example
> why blktap was not migrated to vanilla kernel 3.x?
Blktap3 is under development (https://bitbucket.org/tmakatos/blktap3-patches),
if you search the xen-devel archives for blktap3 you can get a rough idea of its
architecture.
> 
> Regards Andreas
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel

On Mon, 2013-02-04 at 17:45 +0000, Andreas Kinzler
wrote:
> for example why blktap was not migrated to vanilla kernel 3.x? 
The short answer is that it wasn''t felt like it would be acceptable
upstream for various architectural reasons (e.g. it doesn''t need to be
done in the kernel at all, hence blktap3).

Please check the list archives, this has been discussed a few times over
the last couple of years.

Ian.