On Fri, 2019-04-12 at 16:27 +0200, Bjørn Mork wrote: > Johannes Berg <johan...@sipsolutions.net> writes: > > On Wed, 2019-04-10 at 21:54 -0600, Subash Abhinov Kasiviswanathan wrote: > > > > > These packets will be processed as raw IP muxed frames on the PC as > > > well, not as ethernet though. > > > > But in order to transport them, they're always encapsulated in ethernet? > > No. There is no ethernet encapsulation of QMAP muxed frames over USB. > > Same goes for MBIM, BTW. The cdc_mbim driver adds ethernet encapsulation > on the host side, but that is just an unfortunate design decision based > on the flawed assumption that ethernet interfaces are easier to relate > to.
Yes yes, sorry. I snipped too much - we were talking here in the context of capturing the QMAP muxed frames remotely to another system, in particular the strange bridge mode rmnet has. And I said up the thread: > Yeah, I get it, it's just done in a strange way. You'd think adding a > tcpdump or some small application that just resends the packets directly > received from the underlying "real_dev" using a ptype_all socket would > be sufficient? Though perhaps not quite the same performance, but then > you could easily not use an application but a dev_add_pack() thing? Or > probably even tc's mirred? > > And to extend that thought, tc's ife action would let you encapsulate > the things you have in ethernet headers... I think. So basically yes, I know we (should) have only IP frames on the session netdevs, and only QMAP-muxed frames on the underlying netdev (assuming it exists), but I don't see the point in having kernel code to add ethernet headers to send it over some other netdev - you can trivially solve all of that in userspace or quite possibly even in the kernel with existing (tc) infrastructure. johannes
