linux-kernel - Re: [PATCH] perf build: Support passing extra Clang options via EXTRA_BPF

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Message-ID: <20251020101523.GE281971@e132581.arm.com>
Date: Mon, 20 Oct 2025 11:15:23 +0100
From: Leo Yan <leo.yan@....com>
To: Namhyung Kim <namhyung@...nel.org>
Cc: hupu <hupu.gm@...il.com>, acme@...nel.org, adrian.hunter@...el.com,
	alexander.shishkin@...ux.intel.com, irogers@...gle.com,
	jolsa@...nel.org, justinstitt@...gle.com,
	linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
	mark.rutland@....com, mingo@...hat.com, morbo@...gle.com,
	nathan@...nel.org, nick.desaulniers+lkml@...il.com,
	peterz@...radead.org
Subject: Re: [PATCH] perf build: Support passing extra Clang options via
 EXTRA_BPF_FLAGS

On Mon, Oct 20, 2025 at 01:16:46PM +0900, Namhyung Kim wrote:

[...]

> On Mon, Oct 20, 2025 at 10:40:49AM +0800, hupu wrote:
> > When cross-compiling perf with BPF enabled, Clang is invoked during the
> > build. Some cross-compilation environments require additional compiler
> > options, such as `--sysroot` or custom include paths.

[...]

> Leo, are you ok with this?

To be clear, now we are not talking cross build for perf program or any
targeting a CPU arch, it is a build failure for eBPF program.

This patch does not make clear why we cannot build eBPF program in
self-contained way. E.g., after installed kernel headers, why Makefile
misses to include installed headers when build eBPF program.

I am not saying we cannot specify an external sysroot path, but before
proceed that, we should make sure the build can work with self-contained
headers.

Thanks,
Leo