kernel/linux.git/tools/scripts/Makefile.include, branch v6.12.80

tools/build: Fix s390(x) cross-compilation with clang

2025-08-20T16:30:24+00:00

[ Upstream commit a40f0cdce78be8a559ee8a85c908049c65a410b2 ] The heuristic to derive a clang target triple from a GCC one does not work for s390. GCC uses "s390-linux" while clang expects "s390x-linux" or "powerz-linux". Add an explicit override. Signed-off-by: Thomas Weißschuh Link: https://lore.kernel.org/r/20250620-tools-cross-s390-v2-1-ecda886e00e5@linutronix.de Signed-off-by: Thomas Weißschuh Signed-off-by: Sasha Levin

treewide: remove meaningless assignments in Makefiles

2024-02-23T22:19:07+00:00

In Makefiles, $(error ), $(warning ), and $(info ) expand to the empty string, as explained in the GNU Make manual [1]: "The result of the expansion of this function is the empty string." Therefore, they are no-op except for logging purposes. $(shell ...) expands to the output of the command. It expands to the empty string when the command does not print anything to stdout. Hence, $(shell mkdir ...) is no-op except for creating the directory. Remove meaningless assignments. [1]: https://www.gnu.org/software/make/manual/make.html#Make-Control-Functions Signed-off-by: Masahiro Yamada Reviewed-by: Arnaldo Carvalho de Melo Reviewed-by: Ian Rogers Link: https://lore.kernel.org/r/20240221134201.2656908-1-masahiroy@kernel.org Signed-off-by: Namhyung Kim Cc: Mark Rutland Cc: Peter Zijlstra Cc: Adrian Hunter Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Alexander Shishkin Cc: Ingo Molnar Cc: linux-kbuild@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-perf-users@vger.kernel.org

tools/build: Fix -s detection code in tools/scripts/Makefile.include

2023-10-18T22:29:47+00:00

As Dmitry described in [1] changelog the current way of detecting -s option is broken for new make. Changing the tools/build -s option detection the same way as it was fixed for root Makefile in [1]. [1] 4bf73588165b ("kbuild: Port silent mode detection to future gnu make.") Cc: Dmitry Goncharov Signed-off-by: Jiri Olsa Tested-by: Arnaldo Carvalho de Melo Acked-by: Namhyung Kim Cc: Peter Zijlstra Cc: KP Singh Cc: Martin KaFai Lau Cc: Song Liu Cc: Yonghong Song Cc: John Fastabend Cc: Hao Luo Cc: Ian Rogers Cc: Stanislav Fomichev Cc: Daniel Borkmann Cc: Quentin Monnet Cc: Arnaldo Carvalho de Melo Cc: Andrii Nakryiko Cc: Alexei Starovoitov Cc: Ingo Molnar Cc: Alexander Shishkin Cc: bpf@vger.kernel.org Cc: linux-perf-users@vger.kernel.org Link: https://lore.kernel.org/r/20231008212251.236023-3-jolsa@kernel.org Signed-off-by: Namhyung Kim

selftests/bpf: Fix cross compilation with CLANG_CROSS_FLAGS

2023-02-22T21:04:55+00:00

I cross-compile my BPF selftests with the following command: CLANG_CROSS_FLAGS="--target=aarch64-linux-gnu --sysroot=/sysroot/" \ make LLVM=1 CC=clang CROSS_COMPILE=aarch64-linux-gnu- SRCARCH=arm64 (Note the use of CLANG_CROSS_FLAGS to specify a custom sysroot instead of letting clang use gcc's default sysroot) However, CLANG_CROSS_FLAGS gets propagated to host tools builds (libbpf and bpftool) and because they reference it directly in their Makefiles, they end up cross-compiling host objects which results in linking errors. This patch ensures that CLANG_CROSS_FLAGS is reset if CROSS_COMPILE isn't set (for example when reaching a BPF host tool build). Signed-off-by: Florent Revest Link: https://lore.kernel.org/r/20230217151832.27784-1-revest@chromium.org Signed-off-by: Alexei Starovoitov

Merge tag 'kbuild-v5.18-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2022-03-31T18:59:03+00:00

Pull Kbuild updates from Masahiro Yamada: - Add new environment variables, USERCFLAGS and USERLDFLAGS to allow additional flags to be passed to user-space programs. - Fix missing fflush() bugs in Kconfig and fixdep - Fix a minor bug in the comment format of the .config file - Make kallsyms ignore llvm's local labels, .L* - Fix UAPI compile-test for cross-compiling with Clang - Extend the LLVM= syntax to support LLVM= form for using a particular version of LLVm, and LLVM= form for using custom LLVM in a particular directory path. - Clean up Makefiles * tag 'kbuild-v5.18-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: kbuild: Make $(LLVM) more flexible kbuild: add --target to correctly cross-compile UAPI headers with Clang fixdep: use fflush() and ferror() to ensure successful write to files arch: syscalls: simplify uapi/kapi directory creation usr/include: replace extra-y with always-y certs: simplify empty certs creation in certs/Makefile certs: include certs/signing_key.x509 unconditionally kallsyms: ignore all local labels prefixed by '.L' kconfig: fix missing '# end of' for empty menu kconfig: add fflush() before ferror() check kbuild: replace $(if A,A,B) with $(or A,B) kbuild: Add environment variables for userprogs flags kbuild: unify cmd_copy and cmd_shipped

kbuild: Make $(LLVM) more flexible

2022-03-31T03:03:46+00:00

The LLVM make variable allows a developer to quickly switch between the GNU and LLVM tools. However, it does not handle versioned binaries, such as the ones shipped by Debian, as LLVM=1 just defines the tool variables with the unversioned binaries. There was some discussion during the review of the patch that introduces LLVM=1 around versioned binaries, ultimately coming to the conclusion that developers can just add the folder that contains the unversioned binaries to their PATH, as Debian's versioned suffixed binaries are really just symlinks to the unversioned binaries in /usr/lib/llvm-#/bin: $ realpath /usr/bin/clang-14 /usr/lib/llvm-14/bin/clang $ PATH=/usr/lib/llvm-14/bin:$PATH make ... LLVM=1 However, that can be cumbersome to developers who are constantly testing series with different toolchains and versions. It is simple enough to support these versioned binaries directly in the Kbuild system by allowing the developer to specify the version suffix with LLVM=, which is shorter than the above suggestion: $ make ... LLVM=-14 It does not change the meaning of LLVM=1 (which will continue to use unversioned binaries) and it does not add too much additional complexity to the existing $(LLVM) code, while allowing developers to quickly test their series with different versions of the whole LLVM suite of tools. Some developers may build LLVM from source but not add the binaries to their PATH, as they may not want to use that toolchain systemwide. Support those developers by allowing them to supply the directory that the LLVM tools are available in, as it is no more complex to support than the version suffix change above. $ make ... LLVM=/path/to/llvm/ Update and reorder the documentation to reflect these new additions. At the same time, notate that LLVM=0 is not the same as just omitting it altogether, which has confused people in the past. Link: https://lore.kernel.org/r/20200317215515.226917-1-ndesaulniers@google.com/ Link: https://lore.kernel.org/r/20220224151322.072632223@infradead.org/ Suggested-by: Masahiro Yamada Suggested-by: Peter Zijlstra Signed-off-by: Nathan Chancellor Reviewed-by: Kees Cook Reviewed-by: Nick Desaulniers Signed-off-by: Masahiro Yamada

tools: Fix unavoidable GCC call in Clang builds

2022-03-08T22:36:37+00:00

In ChromeOS and Gentoo we catch any unwanted mixed Clang/LLVM and GCC/binutils usage via toolchain wrappers which fail builds. This has revealed that GCC is called unconditionally in Clang configured builds to populate GCC_TOOLCHAIN_DIR. Allow the user to override CLANG_CROSS_FLAGS to avoid the GCC call - in our case we set the var directly in the ebuild recipe. In theory Clang could be able to autodetect these settings so this logic could be removed entirely, but in practice as the commit cebdb7374577 ("tools: Help cross-building with clang") mentions, this does not always work, so giving distributions more control to specify their flags & sysroot is beneficial. Suggested-by: Manoj Gupta Suggested-by: Nathan Chancellor Signed-off-by: Adrian Ratiu Signed-off-by: Daniel Borkmann Acked-by: Nathan Chancellor Cc: Nick Desaulniers Link: https://lore.kernel.org/lkml/87czjk4osi.fsf@ryzen9.i-did-not-set--mail-host-address--so-tickle-me Link: https://lore.kernel.org/bpf/20220308121428.81735-1-adrian.ratiu@collabora.com

tools: Ignore errors from `which' when searching a GCC toolchain

2022-02-01T22:04:12+00:00

When cross-building tools with clang, we run `which $(CROSS_COMPILE)gcc` to detect whether a GCC toolchain provides the standard libraries. It is only a helper because some distros put libraries where LLVM does not automatically find them. On other systems, LLVM detects the libc automatically and does not need this. There, it is completely fine not to have a GCC at all, but some versions of `which' display an error when the command is not found: which: no aarch64-linux-gnu-gcc in ($PATH) Since the error can safely be ignored, throw it to /dev/null. Fixes: cebdb7374577 ("tools: Help cross-building with clang") Reported-by: Nathan Chancellor Signed-off-by: Jean-Philippe Brucker Signed-off-by: Daniel Borkmann Tested-by: Nathan Chancellor Reviewed-by: Nathan Chancellor Link: https://lore.kernel.org/bpf/20220201093119.1713207-1-jean-philippe@linaro.org

tools: Help cross-building with clang

2021-12-16T20:15:04+00:00

Cross-compilation with clang uses the -target parameter rather than a toolchain prefix. Just like the kernel Makefile, add that parameter to CFLAGS when CROSS_COMPILE is set. Unlike the kernel Makefile, we use the --sysroot and --gcc-toolchain options because unlike the kernel, tools require standard libraries. Commit c91d4e47e10e ("Makefile: Remove '--gcc-toolchain' flag") provides some background about --gcc-toolchain. Normally clang finds on its own the additional utilities and libraries that it needs (for example GNU ld or glibc). On some systems however, this autodetection doesn't work. There, our only recourse is asking GCC directly, and pass the result to --sysroot and --gcc-toolchain. Of course that only works when a cross GCC is available. Autodetection worked fine on Debian, but to use the aarch64-linux-gnu toolchain from Archlinux I needed both --sysroot (for crt1.o) and --gcc-toolchain (for crtbegin.o, -lgcc). The --prefix parameter wasn't needed there, but it might be useful on other distributions. Use the CLANG_CROSS_FLAGS variable instead of CLANG_FLAGS because it allows tools such as bpftool, that need to build both host and target binaries, to easily filter out the cross-build flags from CFLAGS. Signed-off-by: Jean-Philippe Brucker Signed-off-by: Andrii Nakryiko Acked-by: Quentin Monnet Acked-by: Nick Desaulniers Link: https://lore.kernel.org/bpf/20211216163842.829836-2-jean-philippe@linaro.org

tools build: Fix quiet cmd indentation

2021-05-17T03:10:03+00:00

The tools quiet cmd output has mismatched indentation (and extra space character between cmd name and target name) compared to the rest of kbuild out: HOSTCC scripts/insert-sys-cert LD /srv/code/tools/objtool/arch/x86/objtool-in.o LD /srv/code/tools/objtool/libsubcmd-in.o AR /srv/code/tools/objtool/libsubcmd.a HOSTLD scripts/genksyms/genksyms CC scripts/mod/empty.o HOSTCC scripts/mod/mk_elfconfig CC scripts/mod/devicetable-offsets.s MKELF scripts/mod/elfconfig.h HOSTCC scripts/mod/modpost.o HOSTCC scripts/mod/file2alias.o HOSTCC scripts/mod/sumversion.o LD /srv/code/tools/objtool/objtool-in.o LINK /srv/code/tools/objtool/objtool HOSTLD scripts/mod/modpost CC kernel/bounds.s Adjust to match the rest of kbuild. Signed-off-by: Kees Cook Signed-off-by: Masahiro Yamada