From: Nathan Chancellor <nathan@kernel.org>
To: Ian Rogers <irogers@google.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>, Connor OBrien <connoro@google.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
bpf@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] tools/resolve_btfids: Tidy host CFLAGS forcing
Date: Wed, 1 Feb 2023 16:31:09 -0700 [thread overview]
Message-ID: <Y9r2Paqbn6PP+EsM@dev-arch.thelio-3990X> (raw)
In-Reply-To: <20230201213743.44674-1-irogers@google.com>
On Wed, Feb 01, 2023 at 01:37:43PM -0800, Ian Rogers wrote:
> Avoid passing CROSS_COMPILE to submakes and ensure CFLAGS is forced to
> HOSTCFLAGS for submake builds. This fixes problems with cross
> compilation.
>
> Tidy to not unnecessarily modify/export CFLAGS, make the override for
> prepare and build clearer.
>
> Fixes: 13e07691a16f ("tools/resolve_btfids: Alter how HOSTCC is forced")
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
I can test alternative solutions as well.
> ---
> tools/bpf/resolve_btfids/Makefile | 49 ++++++++++++++++---------------
> 1 file changed, 26 insertions(+), 23 deletions(-)
>
> diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
> index daed388aa5d7..3ed4e3be4e06 100644
> --- a/tools/bpf/resolve_btfids/Makefile
> +++ b/tools/bpf/resolve_btfids/Makefile
> @@ -17,12 +17,7 @@ else
> MAKEFLAGS=--no-print-directory
> endif
>
> -# always use the host compiler
> -HOST_OVERRIDES := AR="$(HOSTAR)" CC="$(HOSTCC)" LD="$(HOSTLD)" ARCH="$(HOSTARCH)" \
> - EXTRA_CFLAGS="$(HOSTCFLAGS) $(KBUILD_HOSTCFLAGS)"
> -
> RM ?= rm
> -CROSS_COMPILE =
>
> OUTPUT ?= $(srctree)/tools/bpf/resolve_btfids/
>
> @@ -43,8 +38,31 @@ SUBCMD_INCLUDE := $(SUBCMD_DESTDIR)include
> BINARY := $(OUTPUT)/resolve_btfids
> BINARY_IN := $(BINARY)-in.o
>
> +LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null)
> +LIBELF_LIBS := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf)
> +
> +RESOLVE_BTFIDS_CFLAGS = -g \
> + -I$(srctree)/tools/include \
> + -I$(srctree)/tools/include/uapi \
> + -I$(LIBBPF_INCLUDE) \
> + -I$(SUBCMD_INCLUDE) \
> + $(LIBELF_FLAGS)
> +
> +# Overrides for the prepare step libraries.
> +HOST_OVERRIDES_PREPARE := AR="$(HOSTAR)" CC="$(HOSTCC)" LD="$(HOSTLD)" \
> + ARCH="$(HOSTARCH)" CROSS_COMPILE=""
> +
> +# Overrides for Makefile.build C targets.
> +HOST_OVERRIDES_BUILD := $(HOST_OVERRIDES_PREPARE) \
> + CFLAGS="$(HOSTCFLAGS) $(KBUILD_HOSTCFLAGS) $(RESOLVE_BTFIDS_CFLAGS)" \
> +
> +LIBS = $(LIBELF_LIBS) -lz
> +
> all: $(BINARY)
>
> +export srctree OUTPUT Q
> +include $(srctree)/tools/build/Makefile.include
> +
> prepare: $(BPFOBJ) $(SUBCMDOBJ)
>
> $(OUTPUT) $(OUTPUT)/libsubcmd $(LIBBPF_OUT):
> @@ -53,31 +71,16 @@ $(OUTPUT) $(OUTPUT)/libsubcmd $(LIBBPF_OUT):
>
> $(SUBCMDOBJ): fixdep FORCE | $(OUTPUT)/libsubcmd
> $(Q)$(MAKE) -C $(SUBCMD_SRC) OUTPUT=$(SUBCMD_OUT) \
> - DESTDIR=$(SUBCMD_DESTDIR) $(HOST_OVERRIDES) prefix= subdir= \
> + DESTDIR=$(SUBCMD_DESTDIR) $(HOST_OVERRIDES_PREPARE) prefix= subdir= \
> $(abspath $@) install_headers
>
> $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OUT)
> $(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC) OUTPUT=$(LIBBPF_OUT) \
> - DESTDIR=$(LIBBPF_DESTDIR) $(HOST_OVERRIDES) prefix= subdir= \
> + DESTDIR=$(LIBBPF_DESTDIR) $(HOST_OVERRIDES_PREPARE) prefix= subdir= \
> $(abspath $@) install_headers
>
> -LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null)
> -LIBELF_LIBS := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf)
> -
> -CFLAGS += -g \
> - -I$(srctree)/tools/include \
> - -I$(srctree)/tools/include/uapi \
> - -I$(LIBBPF_INCLUDE) \
> - -I$(SUBCMD_INCLUDE) \
> - $(LIBELF_FLAGS)
> -
> -LIBS = $(LIBELF_LIBS) -lz
> -
> -export srctree OUTPUT CFLAGS Q
> -include $(srctree)/tools/build/Makefile.include
> -
> $(BINARY_IN): fixdep FORCE prepare | $(OUTPUT)
> - $(Q)$(MAKE) $(build)=resolve_btfids $(HOST_OVERRIDES)
> + $(Q)$(MAKE) $(build)=resolve_btfids $(HOST_OVERRIDES_BUILD)
>
> $(BINARY): $(BPFOBJ) $(SUBCMDOBJ) $(BINARY_IN)
> $(call msg,LINK,$@)
> --
> 2.39.1.519.gcb327c4b5f-goog
>
prev parent reply other threads:[~2023-02-01 23:31 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-01 21:37 Ian Rogers
2023-02-01 23:31 ` Nathan Chancellor [this message]
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