Re: [PATCH] doc: announce header split deprecation

From: Thomas Monjalon <thomas@monjalon.net>
To: "Ding, Xuan" <xuan.ding@intel.com>
Cc: "andrew.rybchenko@oktetlabs.ru" <andrew.rybchenko@oktetlabs.ru>,
	"mdr@ashroe.eu" <mdr@ashroe.eu>, "dev@dpdk.org" <dev@dpdk.org>,
	"stephen@networkplumber.org" <stephen@networkplumber.org>,
	"mb@smartsharesystems.com" <mb@smartsharesystems.com>,
	"dev@dpdk.org" <dev@dpdk.org>,
	"Zhang, Qi Z" <qi.z.zhang@intel.com>,
	"asekhar@marvell.com" <asekhar@marvell.com>,
	"pbhagavatula@marvell.com" <pbhagavatula@marvell.com>,
	"ferruh.yigit@xilinx.com" <ferruh.yigit@xilinx.com>,
	"grive@u256.net" <grive@u256.net>
Subject: Re: [PATCH] doc: announce header split deprecation
Date: Thu, 14 Jul 2022 10:08:52 +0200	[thread overview]
Message-ID: <6226385.mzcYPaeBD7@thomas> (raw)
In-Reply-To: <BN9PR11MB5513622FEE159BFE8D1C2CC0E7889@BN9PR11MB5513.namprd11.prod.outlook.com>

14/07/2022 07:50, Ding, Xuan:
> From: Thomas Monjalon <thomas@monjalon.net>
> > 23/05/2022 16:20, xuan.ding@intel.com:
> > > From: Xuan Ding <xuan.ding@intel.com>
> > >
> > > RTE_ETH_RX_OFFLOAD_HEADER_SPLIT offload was introduced some time
> > ago
> > > to substitute bit-field header_split in struct rte_eth_rxmode. It
> > > allows to enable header split offload with the header size controlled
> > > using split_hdr_size in the same structure.
> > >
> > > Right now, no single PMD actually supports
> > > RTE_ETH_RX_OFFLOAD_HEADER_SPLIT with above definition. Many examples
> > > and test apps initialize the field to 0 explicitly. The most of
> > > drivers simply ignore split_hdr_size since the offload is not advertised, but
> > some double-check that its value is 0.
> > >
> > > So the RTE_ETH_RX_OFFLOAD_HEADER_SPLIT and split_header_size field
> > > will be removed in DPDK 22.11.
> > >
> > > Signed-off-by: Xuan Ding <xuan.ding@intel.com>
> > > ---
> > >  doc/guides/rel_notes/deprecation.rst | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > >
> > > diff --git a/doc/guides/rel_notes/deprecation.rst
> > > b/doc/guides/rel_notes/deprecation.rst
> > > index 4e5b23c53d..b8114f29ed 100644
> > > --- a/doc/guides/rel_notes/deprecation.rst
> > > +++ b/doc/guides/rel_notes/deprecation.rst
> > > @@ -125,3 +125,7 @@ Deprecation Notices
> > >    applications should be updated to use the ``dmadev`` library instead,
> > >    with the underlying HW-functionality being provided by the ``ioat`` or
> > >    ``idxd`` dma drivers
> > > +
> > > +* ethdev: After bit-field header split was removed, the
> > > +``RTE_ETH_RX_OFFLOAD_HEADER_SPLIT``
> > > +offload and the ``split_hdr_size`` field in structure
> > > +``rte_eth_rxmode`` to enable header split offload are not supported in any
> > PMDs. They will be removed in DPDK 22.11.
> > 
> > It would have been good to talk about rte_eth_rxseg_split which is similar and
> > configured per-queue.
>  
> Thanks for your suggestion.
> 
> But I'm a little confused, are you referring that I need to involve protocol based buffer split?
> About the deprecation of header split, I haven't realized its connection to rte_eth_rxseg_split.

What???
In old versions of your patch "ethdev: introduce protocol type based header split"
you wrote:
"
A new proto field is introduced in the
rte_eth_rxseg_split structure reserved field to specify header protocol
type. With Rx offload flag RTE_ETH_RX_OFFLOAD_HEADER_SPLIT enabled and
protocol type configured, PMD will split the ingress packets into two
separate regions.
"

> Currently there are 2 acks, add more PMD maintainers to help review this deprecation notice
> for header split, thanks a lot!

I cannot say my feeling strong enough.