Monday, April 20, 2020 7:19 PM, Maxime Coquelin: > Cc: Slava Ovsiienko <viachesl...@mellanox.com> > Subject: Re: [PATCH 1/4] vhost: inroduce operation to get vDPA queue stats > > > > On 4/20/20 5:57 PM, Shahaf Shuler wrote: > > Monday, April 20, 2020 10:13 AM, Maxime Coquelin: > >> Subject: Re: [PATCH 1/4] vhost: inroduce operation to get vDPA queue > >> stats > >> > >> Hi Shahaf, > >> > >> On 4/19/20 8:18 AM, Shahaf Shuler wrote: > >>> Thursday, April 16, 2020 4:20 PM, Maxime Coquelin: > >>>> Subject: Re: [PATCH 1/4] vhost: inroduce operation to get vDPA > >>>> queue stats > >>>> > >>>> Hi Matan, > >>>> > >>>> On 4/16/20 11:06 AM, Matan Azrad wrote: > >>>>> Hi Maxime > >>>>> > >>>>> Can you point on specific vendor specific counter I suggested? > >>>> > >>>> No, I can't, but I think we can expect that other vendors may have > >>>> other counters they would be interested to dump. > >>>> > >>>> Maybe Intel has some counters in the IFC that they could dump. > >>>> Xiao, any thoughts? > >>>> > >>>>> I think all of them come directly from virtio protocols. > >>>> > >>>> exceed_max_chain, for example. Doesn't the spec specify that a > >>>> descriptors chain can be as long as the size of the virtqueue? > >>>> > >>>> Here it seems to indicate the device could support less. > >>> > >>> Spec allows device to limit the max supported chain (see [1]). > >> > >> Ha ok, I missed that. Please note that this is only allowed for > >> packed ring, it is not in the split ring part. > > > > On my version of spec (csprd01) it is also for split, however it was removed > on the latest version not sure why.
Actually also for split queue there is this vouge paragraph - https://github.com/oasis-tcs/virtio-spec/blob/master/split-ring.tex#L138 > > Problem is that older drivers may assume max chain size is the virtio ring > size. > > By the way, how is the guest Virtio driver made aware of the max chain size? > Isn't that missing in the spec? Spec gap. Doesn't say how device report, doesn’t device how device should fail and report error. >
