[Qemu-devel] Qemu disaggregation in Xen environment

[Julien Grall <julien.grall@citrix.com>]

Hello,

In the current model, only one instance of qemu is running for each running HVM domain.

We are looking at disaggregating qemu to have, for example, an instance to emulate only
network controllers, another to emulate block devices, etc...

Multiple instances of qemu would run for a single Xen domain. Each one would handle
a subset of the hardware.

Has someone already looked at it and potentially already submitted code for qemu ?
The purpose of this e-mail is to start a discussion and gather opinions on how the
qemu developers community would like to see it implemented.

A couple of questions comes to mind:

1) How hard would it be to untangle "machine" specific (PC hardware) emulation
from "device" specific emulation (PCI devices) ?

2) How can we achieve disaggregation from a configuration point of view. Currently,
Xen toolstack starts qemu, and tells qemu which device to emulate using the command
line. I've heard about a project for creating machine description configuration files
for QEMU which could help greatly in dividing up which hardware to emulate in which
instance of qemu. What is the status of this project ?

Thank you for your answers,