Re: [patch net-next 0/6] selftests: virtio_net: introduce initial testing infrastructure

[Jiri Pirko <jiri@resnulli.us>]

Tue, Apr 16, 2024 at 11:53:35AM CEST, jiri@resnulli.us wrote:
>Mon, Apr 15, 2024 at 07:26:59PM CEST, kuba@kernel.org wrote:
>>On Sat, 13 Apr 2024 15:23:53 +0200 Jiri Pirko wrote:
>>> That is a goal. Currently I do it with:
>>> vng --qemu-opts="-nic tap,id=nd0,ifname=xtap0,model=virtio-net-pci,script=no,downscript=no,mac=52:54:00:12:34:57 -nic tap,id=nd1,ifname=xtap1,model=virtio-net-pci,script=no,downscript=no,mac=52:54:00:12:34:58"
>>> 
>>> and setting loop manually with tc-matchall-mirred
>>> 
>>> Implementing virtio loop instantiation in vng is on the todo list for
>>> this.
>>
>>Just to be clear - I think the loop configuration is better off outside
>>vng. It may need SUID and such. We just need to make vng spawn the two
>>interfaces with a less verbose syntax. --network-count 2 ?
>
>Well, you ask vng for network device by:
>--net=user/bridge
>
>Currently putting the option multiple times is ignored, but I don't see
>why that can't work.
>
>Regarding the loop configuration, I would like to make this as
>convenient for the user as possible, I was thinking about something like
>--net=loop which would create the tc-based loop.
>
>How to do this without root, I'm not sure. Perhaps something similar
>like qemu-bridge-helper could be used.

Ha, qemu knows how to solve this already:
       -netdev hubport,id=id,hubid=hubid[,netdev=nd]
              Create a hub port on the emulated hub with ID hubid.

              The hubport netdev lets you connect a NIC to a QEMU emulated hub
              instead of a single netdev. Alternatively, you can also  connect
              the  hubport to another netdev with ID nd by using the netdev=nd
              option.

I cooked-up a testing vng patch, so the user can pass "--net=loop":
https://github.com/arighi/virtme-ng/commit/84a26ba92c9834c09d16fc1a4dc3a69c4d758236