> From: Ivan Malov [mailto:ivan.ma...@arknetworks.am] > Sent: Monday, 18 August 2025 10.13 > > Hi Morten, > > On Mon, 18 Aug 2025, Morten Brørup wrote: > > <snip> > > > > > Ethtool has both NONE and OTHER: > > > https://git.kernel.org/pub/scm/network/ethtool/ethtool.git/tree/uapi/linux/eth > tool.h#n2242 > > > > Ethtool doesn't have a 3rd value UNKNOWN, and I think having a 3rd value > complicates things too much. > > > > I still think we should consider OTHER==UNKNOWN, and that NONE (having no > connector) cannot happen and thus should be omitted. > > Having more than one of these adds complexity, and I fail to see the > benefit. > > I can imagine the user having a 2-port NIC (and 2 PFs exposed to the host by > default), with only the 1st port having a cable plugged into it, where some > traffic received by the 1st port is intercepted by a 'transfer' flow rule to > be > redirected to the 2nd PF. While the 2nd PF in this case serves some fraction > of > traffic, its LINK_TYPE (or, maybe LINK_TECH) is still 'NONE', as its own > associated network port (the 2nd port) has got no cable.
In this scenario, although the 2nd port has no socket to plug/unplug a cable, I would consider the 2nd port as connected by internal (on-chip) wires, and use the "OTHER" connector type to describe that on-chip connection. But what happens if a cable is also plugged into the 2nd port... now it has two connectors simultaneously. The same could occur to a NIC that is exposed to DPDK as a single port, but is actually connected via a port multiplexer (e.g. a 5-port switch chip) to multiple physical ports. > > Also, perhaps port representors for VFs that can act as 'patch panel' to, say, > set MTU on the target VF, but do not expose Rx/Tx to the DPDK application can > have the link type indicate 'NONE', but this is a bit of a stretch, of course. Yeah, "NONE" might be appropriate here. So the question is: If "NONE" is only relevant for exotic cases like this, should we omit it for simplicity? > > Maybe I'm very wrong in fact, so feel free to disregard my notes. Good, creative input! > > Thank you. > > > > > "Because Ethtool also has NONE" is not a good argument. Linux has plenty of > obsolete stuff, which we don't need to copy to DPDK. > > However, referring to the reason why Ethtool also has NONE (in addition to > OTHER) might reveal a valid argument for having it in DPDK too. > > > > Anyway, if we have more than one value (in addition to the actual physical > connector values), they need good descriptions, so it is crystal clear what > the difference is between NONE and OTHER (and UNKNOWN, if we proceed with this > 3rd value). > > > >
