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RE: [Xen-devel] mini-guest io emulation


Gregor and I have been working on getting Mini-OS to run on x86_64. Here
is the status:

- The hypercall interface has been updated to reflect XenLinux. 
- x86_64 pagetable builder was added. 
- I am currently working on getting the scheduler to work in x86_64 mode
(I will check in something in a couple of days)
- I think Gregor is working on console support. 

Some of the other things that need to be done are:
- Fix traps.c
        a) To show more useful information.
        b) Fix pagetable walk.

- x86_32 PAE

- Look into the stack overrun issue.

We will shortly also have a couple of more people from Unisys investing
time in this effort. 


> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-
> bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Ian Pratt
> Sent: Sunday, March 12, 2006 4:26 PM
> To: xen-devel
> Subject: [Xen-devel] mini-guest io emulation
> Folks,
> At the last summit I presented a proposal for rearchitecting the way
> do io emulation for fully-virtualized (hvm) guests. I'd really like to
> try and get the work to implement this underway, as it cleans up a
> of mess, is a prerequisite for save/restore/relocation of hvm guests,
> and is a precursor to some significant performance improvements. It
> involves a fair chunk of work, so we really want to try and get
> folk working on it.
> The plan is to move the io emulation code (qemu-dm) from running as a
> user-space app in domain 0 into a 'mini guest' that is effectively a
> small paravirtualized guest in the root hardware context associated
> each hvm domain.
> I guess a very high-level work plan would look something like this:
> * get minios running well on x86_64; add a few simple infrastructure
> functions e.g. simple memory allocator. No need for any 'user space'
> support
> * port (simplified)xenbus/netfront/blkfront to minios; test simple
> net/disk IO
> * implement enough infrastructure to allow qemu-dm to be compiled into
> minios, calling into net/blkfront for IO.
> * plumb the vmexit entry points from MMIO and in/out into minios and
> hence qemu-dm
> Once the above is working we'll be in good shape. We can remove all
> skany qemu-dm support from the tools as from their POV paravirt and
> guests will look identical. It should also be easy to implement
> save/restore of hvm guests -- just save the miniguest as part of the
> guests', memory image. The next stage would then be to improve
> performance by enhancing the device models, e.g. adding a network card
> that suports jumbo frames and csum offload, and requires fewer vmexits
> in operation.
> How best to move forward on this? Any volunteers?
> Thanks,
> Ian
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