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From: "Xie, Huawei" <huawei.xie@intel.com>
To: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Thread-Topic: [dpdk-dev] [PATCH v4 7/8] virtio: add 1.0 support
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Date: Tue, 19 Jan 2016 08:02:21 +0000
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Subject: Re: [dpdk-dev] [PATCH v4 7/8] virtio: add 1.0 support
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On 1/19/2016 3:44 PM, Xie, Huawei wrote:=0A=
> On 1/19/2016 1:53 PM, Yuanhan Liu wrote:=0A=
>> On Mon, Jan 18, 2016 at 04:50:16PM +0000, Xie, Huawei wrote:=0A=
>>> On 1/15/2016 12:34 PM, Yuanhan Liu wrote:=0A=
>>>> -static void=0A=
>>>> +static int=0A=
>>>>  virtio_negotiate_features(struct virtio_hw *hw)=0A=
>>>>  {=0A=
>>>>  	uint64_t host_features;=0A=
>>>> @@ -949,6 +949,22 @@ virtio_negotiate_features(struct virtio_hw *hw)=
=0A=
>>>>  	hw->guest_features =3D vtpci_negotiate_features(hw, host_features);=
=0A=
>>> Here if we are not modern device, we should remove VIRTIO_F_VERSION_1 i=
n=0A=
>>> guest features.=0A=
>> VIRTIO_F_VERSION_1 should not be set for legacy virtio device at all.=0A=
> Yes, but here this patch sets this VIRTIO_F_VERSION_1 feature even for=0A=
> legacy virtio device.=0A=
> It doesn't cause issues, but better remove it for legacy virtio device.=
=0A=
=0A=
OK, I see the legacy_get_features return a 32bit value which masks the=0A=
higher bits which contains the host VIRTIO_F_VERSION_1 feature. This is=0A=
very implict.=0A=
=0A=
>> 	--yliu =0A=
>>=0A=
>=0A=
=0A=