Subject: Re: [PATCH] vdpa/mlx5: set_features should allow reset to zero

From: "Michael S. Tsirkin" <[email-masked]>
Date: Wed, 24 Feb 2021 03:43:13 -0500

On Wed, Feb 24, 2021 at 04:26:43PM +0800, Jason Wang wrote:
>     Basically on first guest access QEMU would tell kernel whether
>     guest is using the legacy or the modern interface.
>     E.g. virtio_pci_config_read/virtio_pci_config_write will call ioctl(ENABLE_LEGACY, 1)
>     while virtio_pci_common_read will call ioctl(ENABLE_LEGACY, 0)
> 
> 
> But this trick work only for PCI I think?
> 
> Thanks

ccw has a revision it can check. mmio does not have transitional devices
at all.

-- 
MST