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

Jason Wang <jasowang@xxxxxxxxxx> · Wed, 24 Feb 2021 17:30:37 +0800

On 2021/2/24 4:43 下午, Michael S. Tsirkin wrote:
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.

Ok, then we can do the workaround in the qemu, isn't it?

Thanks

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