Re: [dpdk-dev] [PATCH v6 2/3] ethdev: extend RSS offload types

["Zhang, Qi Z" <qi.z.zhang@intel.com>]

> -----Original Message-----
> From: Andrew Rybchenko [mailto:arybchenko@solarflare.com]
> Sent: Sunday, September 29, 2019 7:41 PM
> To: Su, Simei <simei.su@intel.com>; Zhang, Qi Z <qi.z.zhang@intel.com>; Wu,
> Jingjing <jingjing.wu@intel.com>; Ye, Xiaolong <xiaolong.ye@intel.com>; Yigit,
> Ferruh <ferruh.yigit@intel.com>
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v6 2/3] ethdev: extend RSS offload types
> 
> On 9/29/19 8:11 AM, Simei Su wrote:
> > This patch reserves several bits as input set selection from the high
> > end of the 64 bits. It is combined with exisiting ETH_RSS_* to
> > represent rss types.
> 
> rss -> RSS
> 
> > for example:
> >    ETH_RSS_IPV4 | ETH_RSS_L3_SRC_ONLY: hash on src ip address only
> >    ETH_RSS_IPV4_UDP | ETH_RSS_L4_DST_ONLY: hash on src/dst IP and
> >                                            dst UDP port
> >
> > Signed-off-by: Simei Su <simei.su@intel.com>
> > ---
> >   lib/librte_ethdev/rte_ethdev.h | 13 +++++++++++++
> >   1 file changed, 13 insertions(+)
> >
> > diff --git a/lib/librte_ethdev/rte_ethdev.h
> > b/lib/librte_ethdev/rte_ethdev.h index 7722f70..e68bca8 100644
> > --- a/lib/librte_ethdev/rte_ethdev.h
> > +++ b/lib/librte_ethdev/rte_ethdev.h
> > @@ -505,6 +505,19 @@ struct rte_eth_rss_conf {
> >   #define ETH_RSS_GENEVE             (1ULL << 20)
> >   #define ETH_RSS_NVGRE              (1ULL << 21)
> >
> > +/*
> > + * We use the following macros to combine with above ETH_RSS_* for
> > + * more specific input set selection. These bits are defined starting
> > + * from the high end of the 64 bits.
> > + * Note: If we use above ETH_RSS_* without SRC/DST_ONLY, it
> > +represents
> > + * both SRC and DST are taken into account. SRC_ONLY and DST_ONLY of
> > + * the same level can't be used simultaneously.
> > + */
> > +#define ETH_RSS_L3_SRC_ONLY        (1ULL << 63)
> > +#define ETH_RSS_L3_DST_ONLY        (1ULL << 62)
> > +#define ETH_RSS_L4_SRC_ONLY        (1ULL << 61)
> > +#define ETH_RSS_L4_DST_ONLY        (1ULL << 60)
> > +
> >   #define ETH_RSS_IP ( \
> >   	ETH_RSS_IPV4 | \
> >   	ETH_RSS_FRAG_IPV4 | \
> 
> It could be tricky and inconvenient for apps to avoid both ONLY bits on the
> same level. E.g. if driver/HW supports both only flags, it will be reported in
> caps and if app simply inherits it from caps, both bits will be set.

> 
> Anyway it requires checks in rte_eth_dev_rss_hash_update() and
> rte_eth_dev_configure(). If both only flags are not allows, it should be checked
> and denied. If both only flags are allows and equal to no flags at all, it should
> be simplified automatically to one variant (I would say no flags at all).

OK, with more consideration, it seems allow both flags equal to no flags make things more easy.