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RE: [Xen-devel] RE: Rearchitecting IO Emulation for HVM Guests

We've been working on re-architecting the virtual device drivers (such
as netfront, blkfront) to minimize their Xen or Linux dependencies so
that we can load these drivers on broader ranges of HVM guests. The new
architecture has Xen and non-driver Linux code in the stub domain. 

Our scope at this point is not the IO emulation as in qemu-dm, and I
believe our project and the one below will be complementary to each

> port xenbus/netfront/blkfront to minios

We've ported/moved part of the code above to minios (stub domain) to
make the cleaner netfront and blkfront drivers working, and the
prototype drivers have started working with the stub domain. 

Intel Open Source Technology Center 

-----Original Message-----
From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Ian Pratt
Sent: Thursday, June 08, 2006 5:07 AM
To: Daniel Stekloff
Cc: Natasha Jarymowycz; xen-devel
Subject: [Xen-devel] RE: Rearchitecting IO Emulation for HVM Guests

> Natasha and I are interested in helping with the io emulation work for
> fully virtualized HVM guests you mentioned in your March 12th email:


I think the updated task list probably looks something like:
 1. update qemu-dm to use latest QEMU version (Christian is working on
 2. modify the xen/qemu interface to use the 'v2e' approach (Leendert is
looking at this)
 3. implement 'stub domains' -- rings 1-3 in the root VMCS (normally
used by PV guests) are free for use in HVM domains (we need to have some
discussion on the best way of doing this [*])
 4. run linux in the stub domain with qemu running from an initrd
 5a. link qemu directly against the linux kernel to avoid system calls
 5b. or, link qemu against minios if we have IO support in minios.


[*] do we have a separate domain struct that the scheduler knows is
actually the same as another domain for scheduling/accounting purposes,
or do we modify the domain struct so hvm and pv guests don't share the
same fields? Probably the latter. 

> In the post, you mentioned the following tasks:
> - get minios running on x86_64
> - port xenbus/netfront/blkfront to minios
> - compile qemu-dm into minios
> - redirect IO to qemu-dm in minios
> Since this work started a couple months ago and some of it has been
> accomplished, we'd like to know what the current status is, what
> tasks there are, who's working on those tasks, and if there's anything
> you'd like us to look into.
> Thanks,
> Dan

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