build_libbpf_bootstrap_android (armeabi-v7a) is failing

[anakryiko]

See https://github.com/libbpf/libbpf-bootstrap/actions/runs/14134507187/job/39602857089

Somehow, only armeabi-v7a is failing with a compilation error. Did something changed with how we setup build environment? @waruqi could you please help check this? Thanks!

[waruqi]

xmake did not make any changes. There doesn't seem to be a type definition for trace_event_raw_sched_process_exec.

I don't know where it is defined.

[anakryiko]

@waruqi ah, I finally got what the problem is. We recently switched to using vmlinux.h headers from https://github.com/libbpf/vmlinux.h and it seems like arm's vmlinux.h just doesn't have tracepoint (probably due to kernel config we used to compile the kernel)

[waruqi]

@waruqi ah, I finally got what the problem is. We recently switched to using vmlinux.h headers from https://github.com/libbpf/vmlinux.h and it seems like arm's vmlinux.h just doesn't have tracepoint (probably due to kernel config we used to compile the kernel)

OK, so how do we fix this? Is there anything I can do?

[anakryiko]

@waruqi we'll deal with it from vmlinux.h repo side: we'll re-generate vmlinux.h headers for all architectures from the same kernel version and configuration. Nothing for you to do, thanks! @theihor is going to look at this soon.

[chenhengqi]

It seems like CONFIG_TRACEPOINTS=y is missing.

FYI iovisor/bcc@e28ec71

[theihor]

@anakryiko I haven't figured out how to get trace_event_raw_sched_process_exec in vmlinux.h on arm. It is present on most other arch-es though.

CONFIG_TRACEPOINTS=y disappears on merge with tinyconfig, so I guess a dependency is missing? Any hints?

A (minimal) config I used: vmlinux.h/kconfig

[anakryiko]

@theihor what's the config you are getting on arm? can you share it?

[chenhengqi]

@anakryiko I haven't figured out how to get trace_event_raw_sched_process_exec in vmlinux.h on arm. It is present on most other arch-es though.

CONFIG_TRACEPOINTS=y disappears on merge with tinyconfig, so I guess a dependency is missing? Any hints?

A (minimal) config I used: vmlinux.h/kconfig

I try this locally, you need to remove CONFIG_64BIT=y and add CONFIG_MMU=y for arm build.

[theihor]

@theihor what's the config you are getting on arm? can you share it?

Full config: https://gist.github.com/theihor/3c84d2f7544a24caeaa79f95b5539823

It's produced by:

make tinyconfig
./scripts/kconfig/merge_config.sh" -m "$kbuild_output/.config" "${KCONFIG}"
make olddefconfig

Where ${KCONFIG} is vmlinux.h/kconfig

If I add CONFIG_TRACEPOINTS=y to kconfig, it gets reset.

I try this locally, you need to remove CONFIG_64BIT=y and add CONFIG_MMU=y for arm build.

@chenhengqi thanks, I'll try that. Now that I noticed, it's obvious: 64BIT should be set depending on the target arch.

[theihor]

@chenhengqi @anakryiko ok, so removing CONFIG_64BIT and adding CONFIG_MMU helped to get trace_event_raw_sched_process_exec in vmlinux.h for arm. Resulting config: vmlinux.h/kconfigs/config.arm

I noticed that CONFIG_FPROBE=y also gets removed from .config for arm. I don't know if it's important, lmk.

Adding CONFIG_DYNAMIC_FTRACE=y and CONFIG_DYNAMIC_FTRACE_WITH_ARGS=y didn't help:

# from kernel/trace/Kconfig
config FPROBE
	bool "Kernel Function Probe (fprobe)"
	depends on HAVE_FUNCTION_GRAPH_FREGS && HAVE_FTRACE_GRAPH_FUNC
	depends on DYNAMIC_FTRACE_WITH_ARGS
	select FUNCTION_GRAPH_TRACER
	default n

[anakryiko]

@theihor great! CONFIG_FPROBE isn't mandatory, and it will depend on architecture supporting it. It's just a faster implementation of kprobes/fentries. It's fine, don't worry about debugging it.

[theihor]

Good news everyone! Updated vmlinux.h fixes the arm build: https://github.com/libbpf/libbpf-bootstrap/actions/runs/14369470264/job/40289649724

[theihor]

Closing, since #337 has landed.