> -----Original Message----- > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Neil Horman > Sent: Friday, April 11, 2014 6:45 PM > To: Thomas Monjalon > Cc: dev at dpdk.org > Subject: Re: [dpdk-dev] [PATCH v2 07/11 1/2] vdev: new registration API > > On Fri, Apr 11, 2014 at 06:18:08PM +0200, Thomas Monjalon wrote: > > 2014-04-11 11:50, Neil Horman: > > > > It seems that your patch is not removing > > rte_eth_ring_pair_create/rte_eth_ring_pair_attach so I'm not sure you > > can dynamically change the PMD in this case. > > > Ew, I had missed those calls. Yes, those should be encapsulated as some > driver > ops or some such. I'll look at that when I rebase. Regardless however, I > didn't > mean to state that pmds could be switched while running, only that the pmd to > use could be specified at run time. Though, you're correct, pmd_ring doesn't > seem to hold in line with the other pmds in their isolation. > The ring PMD is probably best treated separately from the other PMDs as it's not really a device poll-mode driver. Instead, it's a general library that presents an API to make a ring, or set of rings, appear as a poll-mode driver ethdev. The EAL command to have one created at startup time was just an addon after-the-fact in case someone might find it useful :-). However, it's primary purpose was to allow applications to be written which could use physical NICs or rings interchangeably. For example, an app with multiple stages in a pipeline, where each stage just reads from an ethdev without caring if it's actually reading from a port or from packets sent from another lcore/function etc. Another example might be where an application wishes to sometimes loop packets back to itself, in this case it uses the C API to create an additional ring ethdev which it uses as output port for any packets it wants looped back - no special handling needed, everything is an ethdev to it on which it calls rx_burst or tx_burst. It's also likely that in future we will develop other libraries which wish to present their functionality via rx_burst/tx_burst functions i.e. as an ethdev.
Regards, /Bruce
