I was referring to the bounce from host kernel to qemu and then back
to the host kernel for my BE driver.
Xen:
guest - guest kernel driver- host kernel driver
For both situations I need a FE and BE driver, but for KVM I need to
modify QEMU and teach it how to pass the virtio calls to my Host
driver. In Xen BE driver and Host driver are the same and I don't have
to recompile any part of Xen.
-Matt
On Mon, Sep 22, 2008 at 5:30 PM, Dong, Eddie [EMAIL PROTECTED] wrote:
Matt Anger wrote:
Thanks for the info, I've been looking into it by trying
to look
around kvm source code.
Apparently I have to write a kernel driver for the guest
os and then
also write backend driver and modify qemu to use it? Is
that correct?
That seems ugly, especially since now my io goes
guest-guest kernel driver-host kernel kvm-qemu-host
kernel driver
With Xen event-channels my driver gets the event
notification directly
with no user space intervention removing the middle 2
steps and I
Why virtio needs start from guest user space while event channel not?
It is exactly same, event channel can start from user space or kernel
space, same for virtio.
The only difference is guest-host communication needs to go thru Qemu
(host process) in your description model, while Xen handle event channel
in hypervisor. But this can be enahnced also IMO by employing a kernel
level device model which does inter-communication for CPU if performance
is critical, but mostly probably not.
don't have to touch any of Xen's codebase. My driver just
registers
for an event-channel.
But you still need the counter part side to handle it.
I think you may want to reuse Xen BE side code which is a wrong
assumption.
Thanks
-Matt
On Fri, Sep 19, 2008 at 12:14 PM, Anthony Liguori
[EMAIL PROTECTED] wrote:
Javier Guerra wrote:
On Fri, Sep 19, 2008 at 1:31 PM, Anthony Liguori
[EMAIL PROTECTED] wrote:
Matt Anger wrote:
Does KVM have any interface similar to event-channels
like Xen does? Basically a way to send notifications
between the host and guest.
virtio is the abstraction we use.
But virtio is based on the standard hardware
interfaces of the PC--PIO, MMIO, and interrupts.
this is rather low-level, it would be nice to have a
multiplatform interface to this abstraction.
That's exactly the purpose of virtio. virtio is a
high-level, cross platform interface. It's been tested
on x86, PPC, s390, and I believe ia64. It also works in
lguest.
It happens to use PIO, MMIO, and interrupts on x86 under
KVM but other virtio implementations exist for other
platforms.
just for kicks, i've found and printed Rusty's paper
about it. hope it's current :-)
The other good thing to look at is the lguest
documentation. You can skip to just the virtio bits if
you're so inclined. It's really quite thoroughly
documented.
Regards,
Anthony Liguori
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