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Subject: RE: virtio: RSS support capa
Date: Sat, 7 Sep 2024 22:55:58 +0200
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Thread-Topic: virtio: RSS support capa
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From: =?iso-8859-1?Q?Morten_Br=F8rup?= <mb@smartsharesystems.com>
To: <maxime.coquelin@redhat.com>, "Chenbo Xia" <chenbox@nvidia.com>,
 <thomas@monjalon.net>, "Ferruh Yigit" <ferruh.yigit@amd.com>,
 <andrew.rybchenko@oktetlabs.ru>
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> From: Morten Br=F8rup [mailto:mb@smartsharesystems.com]
> Sent: Friday, 6 September 2024 21.38
>=20
> Maxime, Chenbo,
>=20
> If the virtio PMD supports RSS, it should be announced in its
> capabilities.
>=20
> I think this should be added to virtio_dev_info_get():
>=20
> 	if (host_features & (1ULL << VIRTIO_NET_F_RSS))
> 		dev_info->rx_offload_capa |=3D RTE_ETH_RX_OFFLOAD_RSS_HASH;

Or perhaps I'm misunderstanding this capability flag.

I thought it indicated RSS ability, i.e. multi-queue, effectively =
shadowing rte_eth_conf.rxmode.mq_mode RTE_ETH_MQ_RX_RSS_FLAG.
But maybe it doesn't. Maybe it indicates the ability to store the RSS =
hash value in the mbuf.

The RTE_ETH_RX_OFFLOAD_RSS_HASH flag is completely undocumented.

Can someone please clarify?