Re: [dpdk-dev] [PATCH v2] ethdev: document RSS default key and types

[Ophir Munk <ophirmu@mellanox.com>]

> -----Original Message-----
> From: Adrien Mazarguil [mailto:adrien.mazarguil@6wind.com]
> Sent: Wednesday, November 07, 2018 11:31 AM
> To: Ophir Munk <ophirmu@mellanox.com>
> Cc: Ferruh Yigit <ferruh.yigit@intel.com>; Andrew Rybchenko
> <arybchenko@solarflare.com>; dev@dpdk.org; Thomas Monjalon
> <thomas@monjalon.net>; Asaf Penso <asafp@mellanox.com>; Shahaf
> Shuler <shahafs@mellanox.com>; Olga Shern <olgas@mellanox.com>
> Subject: Re: [dpdk-dev] [PATCH v2] ethdev: document RSS default key and
> types
> 
> On Wed, Nov 07, 2018 at 09:23:42AM +0000, Ophir Munk wrote:
> > struct rte_flow_action_rss include fields 'key' and 'types'.
> > Field 'key' is a pointer to bytes array (uint8_t *) which contains the
> > specific RSS hash key.
> > If an application is only interested in default RSS operation it
> > should not care about the specific hash key. The application can set
> > the hash key to NULL such that any PMD uses its default RSS key.
> >
> > Field 'types' is a uint64_t bits flag used to specify a specific RSS
> > hash type such as ETH_RSS_IP (see ETH_RSS_*).
> > If an application does not care about the specific RSS type it can set
> > this field to 0 such that any PMD uses its default type.
> >
> > Signed-off-by: Ophir Munk <ophirmu@mellanox.com>
> > ---
> >  lib/librte_ethdev/rte_flow.h | 9 +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/lib/librte_ethdev/rte_flow.h
> > b/lib/librte_ethdev/rte_flow.h index c0fe879..ca9e135 100644
> > --- a/lib/librte_ethdev/rte_flow.h
> > +++ b/lib/librte_ethdev/rte_flow.h
> > @@ -1782,10 +1782,15 @@ struct rte_flow_action_rss {
> >  	 * through.
> >  	 */
> >  	uint32_t level;
> > -	uint64_t types; /**< Specific RSS hash types (see ETH_RSS_*). */
> > +	/**
> > +	 * Specific RSS hash types (see ETH_RSS_*),
> > +	 * or 0 for PMD specific default.
> > +	 */
> > +	uint64_t types;
> >  	uint32_t key_len; /**< Hash key length in bytes. */
> >  	uint32_t queue_num; /**< Number of entries in @p queue. */
> > -	const uint8_t *key; /**< Hash key. */
> > +	/** Hash key, or NULL for PMD specific default key. */
> > +	const uint8_t *key;
> 
> I'd suggest to document that on key_len instead. If key_len is nonzero, key
> cannot be NULL anyway.

The decision if a key/len combination is valid is done in the PMD action validation API.
For example, in MLX5 key==NULL and key_len==40 is accepted. 
The combination key==NULL and key_len==0 should always succeeds, however the "must" parameter for RSS default is key==NULL and not key_len==0.

> 
> >  	const uint16_t *queue; /**< Queue indices to use. */  };
> >
> > --
> > 1.8.3.1
> >
> 
> --
> Adrien Mazarguil
> 6WIND