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Subject: Re: [virtio-comment] [PATCH v4 1/1] virtio-net: Define per-packet hash reporting feature
On Thu, Feb 20, 2020 at 02:41:03AM -0500, Yuri Benditovich wrote: > > > âââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ > > From: "Jason Wang" <jasowang@redhat.com> > To: "Michael S. Tsirkin" <mst@redhat.com> > Cc: "Yuri Benditovich" <yuri.benditovich@daynix.com>, > virtio-comment@lists.oasis-open.org > Sent: Thursday, February 20, 2020 8:38:50 AM > Subject: Re: [virtio-comment] [PATCH v4 1/1] virtio-net: Define per-packet > hash reporting feature > > > On 2020/2/19 äå10:23, Michael S. Tsirkin wrote: > > On Wed, Feb 19, 2020 at 08:27:10PM +0800, Jason Wang wrote: > >> On 2020/2/19 äå3:53, Yuri Benditovich wrote: > >>> The device MUST set \field{rss_max_indirection_table_length} to at > least 128, if it offers > >>> VIRTIO_NET_F_RSS. > >>> @@ -3195,6 +3180,8 @@ \subsection{Device Operation}\label{sec:Device > Types / Network Device / Device O > >>> le16 csum_start; > >>> le16 csum_offset; > >>> le16 num_buffers; > >>> + le32 hash_value; (Only if VIRTIO_NET_F_HASH_REPORT negotiated) > >>> + le16 hash_type; (Only if VIRTIO_NET_F_HASH_REPORT negotiated) > >>> }; > >>> \end{lstlisting} > >> A question here: > >> > >> Consider we introduce VIRTIO_NET_F_FEATURE_INFORMATION in the future: > >> > >> le32 hash_type; // VIRTIO_NET_F_HASH_REPORT > >> le32 feature_information; // VIRTIO_NET_F_FEATURE_INFORMATION > >> > >> What happens if HASH_REPORT is not negotiated, I believe we expect a > stable > >> ABI(offset) here for feature_information? > >> > >> Thanks > >> > > We'll have to decide at that point ... any better ideas? > > > Not sure but something that is self descriptive? (which could be an > overkill for fields that only need few bytes). > > The problem is that the driver typically wants to know the header size from the > beginning to configure SG table. > So any self-descriptive layout seems good but in practice not so usable, IMO. We should also look at packing things more tightly down the road. > > > Thanks > > > This publicly archived list offers a means to provide input to the > OASIS Virtual I/O Device (VIRTIO) TC. > > In order to verify user consent to the Feedback License terms and > to minimize spam in the list archive, subscription is required > before posting. > > Subscribe: virtio-comment-subscribe@lists.oasis-open.org > Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org > List help: virtio-comment-help@lists.oasis-open.org > List archive: https://lists.oasis-open.org/archives/virtio-comment/ > Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf > List Guidelines: https://www.oasis-open.org/policies-guidelines/ > mailing-lists > Committee: https://www.oasis-open.org/committees/virtio/ > Join OASIS: https://www.oasis-open.org/join/ > > >
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