On 07/13/2017 09:34 PM, tom.barbette@xxxxxxxxx wrote:
Hi all, Can XDP be used for "skbuff bypass"? Like a rx_handler but closer to the driver? I'm not very familiar with eBPF, could it be used to pass the kernel to any kernel module or userspace application? It looks to me that bpf_func in struct bpf_prog could be any function that we could use to deviate XDP and use it for that purpose. Correct? Kernel app like Click or OVS could benefit from that as they don't use most skbuff facilities.
You can do a lot of things with eBPF already e.g. take a look at the kernel BPF sample code or BPF selftests e.g. test_l4lb.c, test_xdp.c, etc, or projects like cilium that get compiled from C to BPF bytecode. BPF and XDP is heavily tied together and part of the core kernel, so modular code/hooks like third party kernel modules are not possible. Also f.e. wrt to user space one of the use cases is that you don't need to cross boundaries in the first place when you preprocess in XDP and e.g. apply policy to drop unrelated packets early while remaining ones are forwarded to containers, etc. There's wip to have an OVS data path in BPF/XDP. I currently don't find the slides, but Quentin did a good coverage on it from the last workshop [1], so worth to read up a bit on the topic. [1] https://qmonnet.github.io/whirl-offload/2017/03/03/iovisor-summit-summary/
Thanks, Tom
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