Re: [PATCH V2 00/23] IOREQ feature (+ virtio-mmio) on Arm

[Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>]

Hi Alex.

[sorry for the possible format issues]

I assume this is wiring up the required bits of support to handle the
IOREQ requests in QEMU?

 

No, it is not related to QEMU. We don't run QEMU in our system. Being honest I have never tried to run it)

virtio-disk backend PoC is a completely standalone entity (IOREQ server) which emulates a virtio-mmio disk device.

It is based on code from DEMU (for IOREQ server purposes) and some code from kvmtool to implement virtio protocol,

disk operations over underlying H/W and Xenbus code to be able to read configuration from the Xenstore

(it is configured via domain config file). Last patch in this series (marked as RFC) actually adds required bits to the libxl code.   

 

We are putting together a PoC demo to show
a virtio enabled image (AGL) running on both KVM and Xen hypervisors so
we are keen to see your code as soon as you can share it.

 

Thank you. Sure, I will provide a branch with code by the end of this week.

 

I'm currently preparing a patch series for QEMU which fixes the recent
breakage caused by changes to the build system. As part of that I've
separated CONFIG_XEN and CONFIG_XEN_HVM so it's possible to build
i386-softmmu with unneeded for ARM bits. Hopefully this will allow me to
create a qemu-aarch64-system binary with just the PV related models in
it.

Does it mean that it will be possible to use QEMU in Xen on Arm just for "backend provider" purposes?

 

Talking to Stefano it probably makes sense going forward to introduce a
new IOREQ aware machine type for QEMU that doesn't bring in the rest of
the x86 overhead. I was thinking maybe xenvirt?

You've tested with virtio-block but we'd also like to extend this to
other arbitrary virtio devices. I guess we will need some sort of
mechanism to inform the QEMU command line where each device sits in the
virtio-mmio bus so the FDT Xen delivers to the guest matches up with
what QEMU is ready to serve requests for?

 

I am sorry, I can't provide ideas here, not familiar with QEMU.

But, completely agree, that other virtio devices should be supported.  

 

--

Regards,

Oleksandr Tyshchenko