On 12/20/19 8:20 AM, Björn Töpel wrote:
On 2019-12-19 23:29, Alex Forster wrote:
I though af_xdp landed after jmp32 ?
They were indeed pretty close together, but AF_XDP became usable in
late 2018 with either 4.18 or 4.19. JMP32 landed in early 2019 with
5.1.
Correct, but is anyone really using AF_XDP pre-5.1?
The rationale for doing JMP32:
https://lore.kernel.org/bpf/87v9sip0i8.fsf@xxxxxxx/
I think going forward, a route where different AF_XDP programs is loaded
based on what currently running kernel supports. "Every s^Hcycle is
sacred", and we're actually paying for the extra checks.
Then again, failing to load is still pretty bad. :-) Thanks for fixing this.
Could we simply just test availability of JMP32 in underlying kernel and use
it if available, if not, fall back to regular JMP. libbpf already has infra
for this, so xsk code could make use of it.
Thanks,
Daniel
