On Tue, 10 Jun 2025 22:18:32 +0700 Bui Quang Minh wrote: > >> Furthermore, we are in the zerocopy so we cannot linearize by > >> allocating a large enough buffer to cover the whole frame then copy the > >> frame data to it. That's not zerocopy anymore. Also, XDP socket zerocopy > >> receive has assumption that the packet it receives must from the umem > >> pool. AFAIK, the generic XDP path is for copy mode only. > > Generic XDP == do_xdp_generic(), here I think you mean the normal XDP > > patch in the virtio driver? If so then no, XDP is very much not > > expected to copy each frame before processing. > > Yes, I mean generic XDP = do_xdp_generic(). I mean that we can linearize > the frame if needed (like in netif_skb_check_for_xdp()) in copy mode for > XDP socket but not in zerocopy mode.
Okay, I meant the copies in the driver - virtio calls xdp_linearize_page() in a few places, for normal XDP. > > This is only slightly related to you patch but while we talk about > > multi-buf - in the netdev CI the test which sends ping while XDP > > multi-buf program is attached is really flaky :( > > https://netdev.bots.linux.dev/contest.html?executor=vmksft-drv-hw&test=ping-py.ping-test-xdp-native-mb&ld-cases=1 > > > > metal-drv-hw means the NETIF is the real NIC, right? The "metal" in the name refers to the AWS instance type that hosts the runner. The test runs in a VM over virtio, more details: https://github.com/linux-netdev/nipa/wiki/Running-driver-tests-on-virtio
