Re: Virtio on Xen with Rust

[Oleksandr <olekstysh@xxxxxxxxx>]

On 29.04.22 06:59, Viresh Kumar wrote:


Hello Viresh


> On 29-04-22, 09:18, Viresh Kumar wrote:
> > Now, it was just yesterday that I started looking into MMIO modern stuff as the
> > GPIO device needs it and you sent me working code to look how to do it as well.
> > You saved at least 1-2 days of my time :)
> One question though, do we need to support Legacy mode at all in the work we are
> doing ?

I am not 100% sure I can answer precisely here. virtio-disk backend 
worked perfectly fine in legacy virtio-mmio transport mode
with the latest vanilla Linux. For the "restricted memory access using 
Xen grant mappings" feature to work I had to switch it to use modern 
virtio-mmio transport.
CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS requires the virtio 
devices to support VIRTIO_F_VERSION_1. In addition, we do need 64-bit 
addresses in the virtqueue.
BTW, the virtio-iommu also requires VIRTIO_F_VERSION_1.



>
--
Regards,

Oleksandr Tyshchenko