How to import generated code?

[jgoldverg]

Hello everyone,

This is a noobie set of questions and i hope it does not come off as outlandish or ridiculous. I have recently started learning eBPF and using cilium's impl of it. I have been struggling to create a proper project structure such that I am able to import the generated code from bpf2go into my main.go.

The file system structure is included here

What I cannot figure out is why I am unable to import the generated functions. Any tips on this would be wonderful. For reference I have included the repo link.

My goal is to have my eBPF programs live in a separate package from the generated code, which should also be in its own separate package.

For example assume we have a project root of hello, I would want something like this:
hello/ebpf/counter.c
hello/gen/gen.go
hello/gen/counter_bpfeb.go
hello/gen/counter_bpfeb.o
hello/cmd/hello/main.go

If this structure is not possible what is the advisable structure for such a project?

Best,
Jacob

[lmb]

Can you try changing ident in the bpf2go invocation to have an uppercase? Something like bpf2go Foo code.c. That way the generated types are exported.

[thediveo]

And in case you don't want to export all identifiers, you can do selective type aliasing in your, say, gen.go with a type Foo = genFoo etc. I've done it that way multiple times.

Maybe you want to put the gen package into internal if that would make sense to you? This makes clear that only your module is allowed to directly access it, and otherwise "hands off!"

[Ghostbaby]

@jgoldverg

The issue you're facing is because the types generated by bpf2go aren't being exported (their names don't start with uppercase letters).

In your bpf2go command, you're using a lowercase identifier kprobe:

bpf2go -target $TARGET_GOARCH -go-package binary -output-dir ./binary -cc clang -no-strip kprobe ./bpf/kprobe.c

To solve your problem, change the identifier kprobe to uppercase Kprobe:

bpf2go -target $TARGET_GOARCH -go-package binary -output-dir ./binary -cc clang -no-strip Kprobe ./bpf/kprobe.c

This way, the generated types and functions will start with uppercase letters (e.g., KprobeObjects instead of kprobeObjects), making them exported identifiers that can be accessed from other packages.

For your desired project structure:

hello/ebpf/counter.c
hello/gen/gen.go
hello/gen/counter_bpfeb.go
hello/gen/counter_bpfeb.o
hello/cmd/hello/main.go

You can adjust the bpf2go command to use -go-package gen and -output-dir ./gen, ensuring you use an uppercase identifier.

If you don't want to export all identifiers, you can use selective type aliasing in gen.go:

package gen

// Only export the types you need
type Counter = counterObjects

Hope this helps you resolve your issue!