[dpdk-dev] [PATCH v5 3/8] ethdev: reserve capability flags for PMD-specific API
tiwei.bie at intel.com
Mon Jan 9 04:57:36 CET 2017
On Sun, Jan 08, 2017 at 08:39:55PM +0800, Ananyev, Konstantin wrote:
> Hi Adrien,
> > Hi Konstantin,
> > On Thu, Jan 05, 2017 at 11:32:38AM +0000, Ananyev, Konstantin wrote:
> > > Hi Adrien,
> > >
> > > >
> > > > On Thu, Jan 05, 2017 at 07:56:08AM +0800, Tiwei Bie wrote:
> > > > > On Thu, Jan 05, 2017 at 01:44:18AM +0800, Ananyev, Konstantin wrote:
> > Well my first reply to this thread was asking why isn't the whole API global
> > from the start then?
> That's good question, and my preference would always be to have the
> API to configure this feature as generic one.
> I guess the main reason why it is not right now we don't reach an agreement
> how this API should look like:
> But I'll leave it to the author to provide the real reason here.
Yes, currently this work just provided a thin layer over 82599's
hardware MACsec offload support to allow users configure 82599's
MACsec offload engine. The current API may be too specific and may
need a rework to be used with other NICs.
> > Given there are valid reasons for it not to and no plan to make it so in the
> > near future, applications must be aware that they are including
> > rte_pmd_ixgbe.h to use it. That in itself is a limiting condition, right?
> Yes, it is definitely a limiting factor.
> Though even if API to configure device to use macsec would be PMD specific right now,
> The API to query that capability and the API to use it at datapath (mbuf.ol_flags) still
> can be (and I think should be) device independent and transparent to use.
> > > Yes, right now it is supported only by ixgbe PMD, but why that should be the
> > > reason to treat is as second-class citizen?
> > > Let say PKT_TX_TUNNEL_* offloads also are supported only by one PMD right now.
> > You are right about PKT_TX_TUNNEL_*, however these flags exist on their own
> > and are not tied to any API function calls, unlike in this series where
> > PKT_TX_MACSEC can only be used if the DEV_TX_OFFLOAD_MACSEC_INSERT
> > capability is present
> I don't think PKT_TX_TUNNEL_* 'exists on its own'.
> To use it well behaving app have to:
> 1) Query that device does provide that capability: DEV_TX_OFFLOAD_*_TNL_TSO
> 2) configure PMD( & device) to use that capability
> 3) use that offload at run-time TX code (mb->ol_flags |= ...; mb->tx_offload = ...)
> For PKT_TX_TUNNEL_* 2) is pretty simple - user just need to make sure
> that full-featured TX function will be selected:
> txconf.txq_flags = 0; ...; rte_eth_tx_queue_setup(..., &txconf);
> For TX_MACSEC, as I understand 2) will be more complicated and
> right now is PMD specific, but anyway the main pattern remains the same.
> So at least 1) and 3) could be kept device neutral.
Yes, the PMD-specific APIs focus on the 2nd step:
2) configure PMD( & device) to use that capability
The other parts (querying the capabilities, using the offload
in the datapath, registering the callback, getting the statistics
via xstats) are done in generic way.
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