Does cilium/ebpf help with keeping constants and types in sync between Go and C

[christian-2]

Does cilium/ebpf provide any support for keeping in sync constants and types that refer to maps shared between user-level code written in Go and kernel-level code written in C, or is this out of the scope of this project. I assume it is, but would like to know for sure.

[lmb]

Can you give an example what you mean?

[christian-2]

I'm fairly new to eBPF programming and this is what I face:

An eBPF program written in C and a user-space program written in Go. Both exchange data via an eBPF map. Conceptually, the eBPF map contains a union, so there is a field of type integer (__u64 in C, uint64 in Go) inside that discerns the particular cases. I have a map.go withconst { CASE_1 = atop ... } and a map.h that declares #define CASE_1 0 ....

If the two files get out of sync, things obviously go awry. In order to mitigate against one could link C into Go (this has downsides) or envisage e.g. a tool that can generate one representation from the other (e.g. Go from C).

So this is the area I had in mind. Is it clearer now?

[brycekahle]

You should look into using go tool cgo -godefs types.go against a file like this:

//go:build ignore

package mypkg

/*
#include "./types.h"
*/
import "C"

type MyGoType C.my_c_type

[thediveo]

how does this work with defines? it seems to cover only types.

[christian-2]

@brycekahle Perfect, thank you.