LinuxLists.cc - [PATCH] tools/build: Add clang cross-compilation flags to feature detection

2023-11-02 08:14:54

Subject: [PATCH] tools/build: Add clang cross-compilation flags to feature detection

From: Björn Töpel <[email protected]>

When a tool cross-build has LLVM=1 set, the clang cross-compilation
flags are not passed to the feature detection build system. This
results in the host's features are detected instead of the targets.

E.g, triggering a cross-build of bpftool:

cd tools/bpf/bpftool
make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- LLVM=1

would report the host's, and not the target's features.

Correct the issue by passing the CLANG_CROSS_FLAGS variable to the
feature detection makefile.

Fixes: cebdb7374577 ("tools: Help cross-building with clang")
Signed-off-by: Björn Töpel <[email protected]>
---
tools/build/Makefile.feature | 2 +-
tools/build/feature/Makefile | 8 ++++----
2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index 934e2777a2db..25b009a6c05f 100644
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -8,7 +8,7 @@ endif

feature_check = $(eval $(feature_check_code))
define feature_check_code
- feature-$(1) := $(shell $(MAKE) OUTPUT=$(OUTPUT_FEATURES) CC="$(CC)" CXX="$(CXX)" CFLAGS="$(EXTRA_CFLAGS) $(FEATURE_CHECK_CFLAGS-$(1))" CXXFLAGS="$(EXTRA_CXXFLAGS) $(FEATURE_CHECK_CXXFLAGS-$(1))" LDFLAGS="$(LDFLAGS) $(FEATURE_CHECK_LDFLAGS-$(1))" -C $(feature_dir) $(OUTPUT_FEATURES)test-$1.bin >/dev/null 2>/dev/null && echo 1 || echo 0)
+ feature-$(1) := $(shell $(MAKE) OUTPUT=$(OUTPUT_FEATURES) CC="$(CC)" CXX="$(CXX)" CFLAGS="$(EXTRA_CFLAGS) $(FEATURE_CHECK_CFLAGS-$(1))" CXXFLAGS="$(EXTRA_CXXFLAGS) $(FEATURE_CHECK_CXXFLAGS-$(1))" LDFLAGS="$(LDFLAGS) $(FEATURE_CHECK_LDFLAGS-$(1))" CLANG_CROSS_FLAGS="$(CLANG_CROSS_FLAGS)" -C $(feature_dir) $(OUTPUT_FEATURES)test-$1.bin >/dev/null 2>/dev/null && echo 1 || echo 0)
endef

feature_set = $(eval $(feature_set_code))
diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index dad79ede4e0a..0231a53024c7 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -84,12 +84,12 @@ PKG_CONFIG ?= $(CROSS_COMPILE)pkg-config

all: $(FILES)

-__BUILD = $(CC) $(CFLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.c,$(@F)) $(LDFLAGS)
+__BUILD = $(CC) $(CFLAGS) $(CLANG_CROSS_FLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.c,$(@F)) $(LDFLAGS)
BUILD = $(__BUILD) > $(@:.bin=.make.output) 2>&1
BUILD_BFD = $(BUILD) -DPACKAGE='"perf"' -lbfd -ldl
BUILD_ALL = $(BUILD) -fstack-protector-all -O2 -D_FORTIFY_SOURCE=2 -ldw -lelf -lnuma -lelf -lslang $(FLAGS_PERL_EMBED) $(FLAGS_PYTHON_EMBED) -DPACKAGE='"perf"' -lbfd -ldl -lz -llzma -lzstd -lcap

-__BUILDXX = $(CXX) $(CXXFLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.cpp,$(@F)) $(LDFLAGS)
+__BUILDXX = $(CXX) $(CXXFLAGS) $(CLANG_CROSS_FLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.cpp,$(@F)) $(LDFLAGS)
BUILDXX = $(__BUILDXX) > $(@:.bin=.make.output) 2>&1

###############################
@@ -259,10 +259,10 @@ $(OUTPUT)test-reallocarray.bin:
$(BUILD)

$(OUTPUT)test-libbfd-liberty.bin:
- $(CC) $(CFLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty
+ $(CC) $(CFLAGS) $(CLANG_CROSS_FLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty

$(OUTPUT)test-libbfd-liberty-z.bin:
- $(CC) $(CFLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty -lz
+ $(CC) $(CFLAGS) $(CLANG_CROSS_FLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty -lz

$(OUTPUT)test-cplus-demangle.bin:
$(BUILD) -liberty

base-commit: 21e80f3841c01aeaf32d7aee7bbc87b3db1aa0c6
--
2.40.1

2023-11-02 09:30:19

by Jiri Olsa

[permalink] [raw]

Subject: Re: [PATCH] tools/build: Add clang cross-compilation flags to feature detection

On Thu, Nov 02, 2023 at 09:14:41AM +0100, Bj?rn T?pel wrote:
> From: Bj?rn T?pel <[email protected]>
>
> When a tool cross-build has LLVM=1 set, the clang cross-compilation
> flags are not passed to the feature detection build system. This
> results in the host's features are detected instead of the targets.
>
> E.g, triggering a cross-build of bpftool:
>
> cd tools/bpf/bpftool
> make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- LLVM=1
>
> would report the host's, and not the target's features.
>
> Correct the issue by passing the CLANG_CROSS_FLAGS variable to the
> feature detection makefile.
>
> Fixes: cebdb7374577 ("tools: Help cross-building with clang")
> Signed-off-by: Bj?rn T?pel <[email protected]>
> ---
> tools/build/Makefile.feature | 2 +-
> tools/build/feature/Makefile | 8 ++++----
> 2 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
> index 934e2777a2db..25b009a6c05f 100644
> --- a/tools/build/Makefile.feature
> +++ b/tools/build/Makefile.feature
> @@ -8,7 +8,7 @@ endif
>
> feature_check = $(eval $(feature_check_code))
> define feature_check_code
> - feature-$(1) := $(shell $(MAKE) OUTPUT=$(OUTPUT_FEATURES) CC="$(CC)" CXX="$(CXX)" CFLAGS="$(EXTRA_CFLAGS) $(FEATURE_CHECK_CFLAGS-$(1))" CXXFLAGS="$(EXTRA_CXXFLAGS) $(FEATURE_CHECK_CXXFLAGS-$(1))" LDFLAGS="$(LDFLAGS) $(FEATURE_CHECK_LDFLAGS-$(1))" -C $(feature_dir) $(OUTPUT_FEATURES)test-$1.bin >/dev/null 2>/dev/null && echo 1 || echo 0)
> + feature-$(1) := $(shell $(MAKE) OUTPUT=$(OUTPUT_FEATURES) CC="$(CC)" CXX="$(CXX)" CFLAGS="$(EXTRA_CFLAGS) $(FEATURE_CHECK_CFLAGS-$(1))" CXXFLAGS="$(EXTRA_CXXFLAGS) $(FEATURE_CHECK_CXXFLAGS-$(1))" LDFLAGS="$(LDFLAGS) $(FEATURE_CHECK_LDFLAGS-$(1))" CLANG_CROSS_FLAGS="$(CLANG_CROSS_FLAGS)" -C $(feature_dir) $(OUTPUT_FEATURES)test-$1.bin >/dev/null 2>/dev/null && echo 1 || echo 0)
> endef
>
> feature_set = $(eval $(feature_set_code))
> diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
> index dad79ede4e0a..0231a53024c7 100644
> --- a/tools/build/feature/Makefile
> +++ b/tools/build/feature/Makefile
> @@ -84,12 +84,12 @@ PKG_CONFIG ?= $(CROSS_COMPILE)pkg-config
>
> all: $(FILES)
>
> -__BUILD = $(CC) $(CFLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.c,$(@F)) $(LDFLAGS)
> +__BUILD = $(CC) $(CFLAGS) $(CLANG_CROSS_FLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.c,$(@F)) $(LDFLAGS)
> BUILD = $(__BUILD) > $(@:.bin=.make.output) 2>&1
> BUILD_BFD = $(BUILD) -DPACKAGE='"perf"' -lbfd -ldl
> BUILD_ALL = $(BUILD) -fstack-protector-all -O2 -D_FORTIFY_SOURCE=2 -ldw -lelf -lnuma -lelf -lslang $(FLAGS_PERL_EMBED) $(FLAGS_PYTHON_EMBED) -DPACKAGE='"perf"' -lbfd -ldl -lz -llzma -lzstd -lcap
>
> -__BUILDXX = $(CXX) $(CXXFLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.cpp,$(@F)) $(LDFLAGS)
> +__BUILDXX = $(CXX) $(CXXFLAGS) $(CLANG_CROSS_FLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.cpp,$(@F)) $(LDFLAGS)
> BUILDXX = $(__BUILDXX) > $(@:.bin=.make.output) 2>&1
>
> ###############################
> @@ -259,10 +259,10 @@ $(OUTPUT)test-reallocarray.bin:
> $(BUILD)
>
> $(OUTPUT)test-libbfd-liberty.bin:
> - $(CC) $(CFLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty
> + $(CC) $(CFLAGS) $(CLANG_CROSS_FLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty
>
> $(OUTPUT)test-libbfd-liberty-z.bin:
> - $(CC) $(CFLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty -lz
> + $(CC) $(CFLAGS) $(CLANG_CROSS_FLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty -lz

should we add this also to test-compile-32.bin/test-compile-x32.bin
targets?

jirka

>
> $(OUTPUT)test-cplus-demangle.bin:
> $(BUILD) -liberty
>
> base-commit: 21e80f3841c01aeaf32d7aee7bbc87b3db1aa0c6
> --
> 2.40.1
>
>

2023-11-02 09:53:30

by Björn Töpel

[permalink] [raw]

Subject: Re: [PATCH] tools/build: Add clang cross-compilation flags to feature detection

Jiri Olsa <[email protected]> writes:

> On Thu, Nov 02, 2023 at 09:14:41AM +0100, Björn Töpel wrote:
>> From: Björn Töpel <[email protected]>
>>
>> When a tool cross-build has LLVM=1 set, the clang cross-compilation
>> flags are not passed to the feature detection build system. This
>> results in the host's features are detected instead of the targets.
>>
>> E.g, triggering a cross-build of bpftool:
>>
>> cd tools/bpf/bpftool
>> make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- LLVM=1
>>
>> would report the host's, and not the target's features.
>>
>> Correct the issue by passing the CLANG_CROSS_FLAGS variable to the
>> feature detection makefile.
>>
>> Fixes: cebdb7374577 ("tools: Help cross-building with clang")
>> Signed-off-by: Björn Töpel <[email protected]>
>> ---
>> tools/build/Makefile.feature | 2 +-
>> tools/build/feature/Makefile | 8 ++++----
>> 2 files changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
>> index 934e2777a2db..25b009a6c05f 100644
>> --- a/tools/build/Makefile.feature
>> +++ b/tools/build/Makefile.feature
>> @@ -8,7 +8,7 @@ endif
>>
>> feature_check = $(eval $(feature_check_code))
>> define feature_check_code
>> - feature-$(1) := $(shell $(MAKE) OUTPUT=$(OUTPUT_FEATURES) CC="$(CC)" CXX="$(CXX)" CFLAGS="$(EXTRA_CFLAGS) $(FEATURE_CHECK_CFLAGS-$(1))" CXXFLAGS="$(EXTRA_CXXFLAGS) $(FEATURE_CHECK_CXXFLAGS-$(1))" LDFLAGS="$(LDFLAGS) $(FEATURE_CHECK_LDFLAGS-$(1))" -C $(feature_dir) $(OUTPUT_FEATURES)test-$1.bin >/dev/null 2>/dev/null && echo 1 || echo 0)
>> + feature-$(1) := $(shell $(MAKE) OUTPUT=$(OUTPUT_FEATURES) CC="$(CC)" CXX="$(CXX)" CFLAGS="$(EXTRA_CFLAGS) $(FEATURE_CHECK_CFLAGS-$(1))" CXXFLAGS="$(EXTRA_CXXFLAGS) $(FEATURE_CHECK_CXXFLAGS-$(1))" LDFLAGS="$(LDFLAGS) $(FEATURE_CHECK_LDFLAGS-$(1))" CLANG_CROSS_FLAGS="$(CLANG_CROSS_FLAGS)" -C $(feature_dir) $(OUTPUT_FEATURES)test-$1.bin >/dev/null 2>/dev/null && echo 1 || echo 0)
>> endef
>>
>> feature_set = $(eval $(feature_set_code))
>> diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
>> index dad79ede4e0a..0231a53024c7 100644
>> --- a/tools/build/feature/Makefile
>> +++ b/tools/build/feature/Makefile
>> @@ -84,12 +84,12 @@ PKG_CONFIG ?= $(CROSS_COMPILE)pkg-config
>>
>> all: $(FILES)
>>
>> -__BUILD = $(CC) $(CFLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.c,$(@F)) $(LDFLAGS)
>> +__BUILD = $(CC) $(CFLAGS) $(CLANG_CROSS_FLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.c,$(@F)) $(LDFLAGS)
>> BUILD = $(__BUILD) > $(@:.bin=.make.output) 2>&1
>> BUILD_BFD = $(BUILD) -DPACKAGE='"perf"' -lbfd -ldl
>> BUILD_ALL = $(BUILD) -fstack-protector-all -O2 -D_FORTIFY_SOURCE=2 -ldw -lelf -lnuma -lelf -lslang $(FLAGS_PERL_EMBED) $(FLAGS_PYTHON_EMBED) -DPACKAGE='"perf"' -lbfd -ldl -lz -llzma -lzstd -lcap
>>
>> -__BUILDXX = $(CXX) $(CXXFLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.cpp,$(@F)) $(LDFLAGS)
>> +__BUILDXX = $(CXX) $(CXXFLAGS) $(CLANG_CROSS_FLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.cpp,$(@F)) $(LDFLAGS)
>> BUILDXX = $(__BUILDXX) > $(@:.bin=.make.output) 2>&1
>>
>> ###############################
>> @@ -259,10 +259,10 @@ $(OUTPUT)test-reallocarray.bin:
>> $(BUILD)
>>
>> $(OUTPUT)test-libbfd-liberty.bin:
>> - $(CC) $(CFLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty
>> + $(CC) $(CFLAGS) $(CLANG_CROSS_FLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty
>>
>> $(OUTPUT)test-libbfd-liberty-z.bin:
>> - $(CC) $(CFLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty -lz
>> + $(CC) $(CFLAGS) $(CLANG_CROSS_FLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty -lz
>
> should we add this also to test-compile-32.bin/test-compile-x32.bin
> targets?

Ah, yes!

I'll spin a v2 with:
diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index 0231a53024c7..c4458345e564 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -283,10 +283,10 @@ $(OUTPUT)test-libbabeltrace.bin:
$(BUILD) # -lbabeltrace provided by $(FEATURE_CHECK_LDFLAGS-libbabeltrace)

$(OUTPUT)test-compile-32.bin:
- $(CC) -m32 -o $@ test-compile.c
+ $(CC) $(CLANG_CROSS_FLAGS) -m32 -o $@ test-compile.c

$(OUTPUT)test-compile-x32.bin:
- $(CC) -mx32 -o $@ test-compile.c
+ $(CC) $(CLANG_CROSS_FLAGS) -mx32 -o $@ test-compile.c

$(OUTPUT)test-zlib.bin:
$(BUILD) -lz

Thanks for having a look, jirka!

Björn