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Subject: Re: [PATCH] vdpa/mlx5: set_features should allow reset to zero
To:     "Michael S. Tsirkin" <mst@redhat.com>
Cc:     Si-Wei Liu <si-wei.liu@oracle.com>, elic@nvidia.com,
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From:   Jason Wang <jasowang@redhat.com>
Message-ID: <d2992c03-d639-54e3-4599-c168ceeac148@redhat.com>
Date:   Wed, 24 Feb 2021 17:30:37 +0800
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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