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From: Wei Xu <wexu@redhat.com>
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Date: Mon, 5 Sep 2016 10:26:28 +0800
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Subject: Re: [Qemu-devel] [PATCH for 2.8 02/11] virtio: convert to use DMA
 api
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To: Jason Wang <jasowang@redhat.com>, mst@redhat.com, qemu-devel@nongnu.org
Cc: pbonzini@redhat.com, peterx@redhat.com, cornelia.huck@de.ibm.com, vkaplans@redhat.com, Stefan Hajnoczi <stefanha@redhat.com>, Kevin Wolf <kwolf@redhat.com>, Amit Shah <amit.shah@redhat.com>, qemu-block@nongnu.org

On 2016=E5=B9=B408=E6=9C=8830=E6=97=A5 11:06, Jason Wang wrote:
> @@ -1587,6 +1595,11 @@ static void virtio_pci_device_plugged(DeviceStat=
e *d, Error **errp)
>       }
>
>       if (legacy) {
> +        if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) {
> +            error_setg(errp, "VIRTIO_F_IOMMU_PLATFORM was supported by=
"
> +                       "neither legacy nor transitional device.");
> +            return ;
> +        }

Not sure if i understand it correctly, the transitional device here=20
maybe a bit hard to understand, just a tip for your convenience,
besides the denied prompt, can we add what kind of device is supported=20
to the message? such as modern device only, like this.

"VIRTIO_F_IOMMU_PLATFORM is supported by modern device only, it
is not supported by either legacy or transitional device."

>           /* legacy and transitional */
>           pci_set_word(config + PCI_SUBSYSTEM_VENDOR_ID,
>                        pci_get_word(config + PCI_VENDOR_ID));