[openstack-dev] vGPUs support for Nova - Implementation

Bob Ball bob.ball at citrix.com
Fri Sep 29 16:51:10 UTC 2017

Hi Sahid,

> > a second device emulator along-side QEMU.  There is no mdev 
> > integration.  I'm concerned about how much mdev-specific functionality 
> > would have to be faked up in the XenServer-specific driver for vGPU to 
> > be used in this way.
> What you are refering with your DEMU it's what QEMU/KVM have with its vfio-pci. XenServer is
> reading through MDEV since the vendors provide drivers on *Linux* using the MDEV framework.
> MDEV is a kernel layer, used to expose hardwares, it's not hypervisor specific.

It is possible that the vendor's userspace libraries use mdev, however DEMU has no concept of mdev at all.  If the vendor's userspace libraries do use mdev then this is entirely abstracted from XenServer's integration.
While I don't have access to the vendors source for the userspace libraries or the kernel module my understanding was that the kernel module in XenServer's integration is for the userspace libraries to talk to the kernel module and for IOCTLS.

My reading of mdev implies that /sys/class/mdev_bus should exist for it to be used?  It does not exist in XenServer, which to me implies that the vendor's driver for XenServer do not use mdev?


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