eBPF on OpenWrt

crashloop_backoff · January 23, 2023, 7:46pm

Hey folks,

Has anyone tried to compile ebpf/xdp code on top of openwrt. I have installed openwrt on raspberry pi and tried to compile a sample ebpf program and found it lacks some tools/packages like clang, etc.. If anyone has done this before please share some guide/articles to setup a ebpf development environment on openwrt.

I also tried to run tracee which is BTF enabled(Compile once run anywhere), but it failed with the following error

unexpected ( at line 2

If anyone has tried these out before share some resources please.

slh · January 24, 2023, 5:18am

You will need to cross-compile at (firmware-)build time, see qosify as an example.

dhewg · January 24, 2023, 10:01am

For xdp-tools, there's an open PR which also contains some background about why this isn't as easy as one might hope:

github.com/openwrt/openwrt

xdp-tools: fix compilation wrongly using host header

openwrt:master ← Ansuel:fix-xdp-tools

opened 07:57PM - 18 Jan 23 UTC

Ansuel

+333 -6

Currently it's needed to have gcc-multilib on the host to correctly compile xdp…-tools. This is wrong and means that we are using host header to compile a tool. By some searching in how the makefile works it was discovered that BPF_CFLAGS were not used and required to be appended to config.mk Only one single header was added but we should include each BPF_CFLAGS from bpf.mk. To make this some patching to bpf-header were required and some patches to xdp-tools were required. Also it's needed to pass the correct target to BPF_CFLAGS. With the following changes xdp-tools can correctly compile with each header from bpf-headers and should not use any host header. Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

Could you please test that and leave a comment there if it works?
Specifically, these two top commits: https://github.com/dhewg/openwrt/commits/xdp

crashloop_backoff · January 28, 2023, 7:05am

@dhewg I'm new to openWRT space,

Could you please test that

Does this mean I have compile it from those commits and flash it to Raspberry pi and check if I can compile my eBPF programs?