[Xen-ia64-devel] Re: [Xen-devel] [RFC][PATCH]mini-os: big-endian mini-os on ia64

[Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxxxxxxx>]

Am Mittwoch, 21. Februar 2007 14:51 schrieb Keir Fraser:
> On 21/2/07 13:04, "Dietmar Hahn" <dietmar.hahn@xxxxxxxxxxxxxxxxxxx> wrote:
> > I think the SWAP()'s are not that much. Maybe I can reduce this by moving
> > some into the ia64-hypercall interface. What remain are the accesses to
> > the ring buffers (not that simple in netfront because of the xen-macros).
> > Perhaps some other guys contribute their opinion.
>
> I would actually argue that they're scattered all over the place and it
> will be hard to be sure that we have all the SWAPs we need and only the
> SWAPs we need. Particularly to continue ensuring that given that most
> development will be with minios having same endianness as Xen.
>
> In short: it's ugly and unless someone really cares it will rot.
>
>  -- Keir

Now that the environment (libxc, xen-ia64) is ready to start a simple BE domU, 
I want to start a new discussion about BE able mini-os.
What I want to have is a mini-os, where everybody whith ia64 hardware can 
build and run a BE mini-os beside LE mini-os (or other domU's) on xen-ia64 
hypervisor. If you say at this point: no interrest for such a thing, than we 
can stop this discussion here.
On the other side we should discuss how this can be realized.
My target with the first patch was to minimize the impact on common mini-os 
source as small as possible and that the hypervisor shouldn't be touched by 
BE/LE problematic. Therewidth I did only the SWAPs at the right place in the 
mini-os. Maybe that SWAPs are ugly but the SWAPs have to be done somewhere 
and the best place in my opinion is in the domU at the lowest level functions 
on top of the hypervisor interface - in gnttab, xenbus, xencons, event.
The other way would be building wrappers around all the accesses to 
domU/hypervisor interfaces and hide the SWAPs there. But this seems a little 
bit overkill at this stage.
Oh and yes I will care about this in the mini-os!
Thanks.

Dietmar

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