kernel/linux.git/scripts/Makefile.clang, branch v6.19.11

kbuild: clang: Support building UM with SUBARCH=i386

2025-03-04T17:40:13+00:00

The UM builds distinguish i386 from x86_64 via SUBARCH, but we don't support building i386 directly with Clang. To make SUBARCH work for i386 UM, we need to explicitly test for it. This lets me run i386 KUnit tests with Clang: $ ./tools/testing/kunit/kunit.py run \ --make_options LLVM=1 \ --make_options SUBARCH=i386 ... Fixes: c7500c1b53bf ("um: Allow builds with Clang") Reviewed-by: Nathan Chancellor Link: https://lore.kernel.org/r/20250304162124.it.785-kees@kernel.org Tested-by: David Gow Signed-off-by: Kees Cook

sparc/build: Add SPARC target flags for compiling with clang

2024-11-16T08:52:56+00:00

clang only supports building 64-bit kernel, so we use the sparc64-linux-gnu target. See also: https://lore.kernel.org/lkml/e26PTXUXEz8OYXmaeKn4Mpuejr4IOlFfFwdB5vpsluXlYiqDdlyQTYcDtdAny_o4gO4SfPeQCCN2qpyT6e0nog5EaP3xk2SeUPTrF54p1gM=@protonmail.com/T/#m068e010dcf8b99d3510a90d7532bcdb70e2e2c6b Signed-off-by: Koakuma Acked-by: Masahiro Yamada Acked-by: Nathan Chancellor Reviewed-by: Andreas Larsson Link: https://lore.kernel.org/r/20241029-sparc-cflags-v3-2-b28745a6bd71@protonmail.com Signed-off-by: Andreas Larsson

Merge tag 'kbuild-v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2023-07-01T16:24:31+00:00

Pull Kbuild updates from Masahiro Yamada: - Remove the deprecated rule to build *.dtbo from *.dts - Refactor section mismatch detection in modpost - Fix bogus ARM section mismatch detections - Fix error of 'make gtags' with O= option - Add Clang's target triple to KBUILD_CPPFLAGS to fix a build error with the latest LLVM version - Rebuild the built-in initrd when KBUILD_BUILD_TIMESTAMP is changed - Ignore more compiler-generated symbols for kallsyms - Fix 'make local*config' to handle the ${CONFIG_FOO} form in Makefiles - Enable more kernel-doc warnings with W=2 - Refactor by generating KSYMTAB data by modpost - Deprecate and - Remove the EXPORT_DATA_SYMBOL macro - Move the check for static EXPORT_SYMBOL back to modpost, which makes the build faster - Re-implement CONFIG_TRIM_UNUSED_KSYMS with one-pass algorithm - Warn missing MODULE_DESCRIPTION when building modules with W=1 - Make 'make clean' robust against too long argument error - Exclude more objects from GCOV to fix CFI failures with GCOV - Allow 'make modules_install' to install modules.builtin and modules.builtin.modinfo even when CONFIG_MODULES is disabled - Include modules.builtin and modules.builtin.modinfo in the linux-image Debian package even when CONFIG_MODULES is disabled - Revive "Entering directory" logging for the latest Make version * tag 'kbuild-v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (72 commits) modpost: define more R_ARM_* for old distributions kbuild: revive "Entering directory" for Make >= 4.4.1 kbuild: set correct abs_srctree and abs_objtree for package builds scripts/mksysmap: Ignore prefixed KCFI symbols kbuild: deb-pkg: remove the CONFIG_MODULES check in buildeb kbuild: builddeb: always make modules_install, to install modules.builtin* modpost: continue even with unknown relocation type modpost: factor out Elf_Sym pointer calculation to section_rel() modpost: factor out inst location calculation to section_rel() kbuild: Disable GCOV for *.mod.o kbuild: Fix CFI failures with GCOV kbuild: make clean rule robust against too long argument error script: modpost: emit a warning when the description is missing kbuild: make modules_install copy modules.builtin(.modinfo) linux/export.h: rename 'sec' argument to 'license' modpost: show offset from symbol for section mismatch warnings modpost: merge two similar section mismatch warnings kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion modpost: use null string instead of NULL pointer for default namespace modpost: squash sym_update_namespace() into sym_add_exported() ...

Makefile: Add loongarch target flag for Clang compilation

2023-06-29T12:58:43+00:00

The LoongArch kernel is 64-bit and built with the soft-float ABI, hence the loongarch64-linux-gnusf target. (The "libc" part can affect the codegen of libcalls: other arches do not use a bare-metal target, and currently the only fully supported libc on LoongArch is glibc anyway.) See: https://lore.kernel.org/loongarch/CAKwvOdnimxv8oJ4mVY74zqtt1x7KTMrWvn2_T9x22SFDbU6rHQ@mail.gmail.com/ Reviewed-by: Nick Desaulniers Signed-off-by: WANG Xuerui Signed-off-by: Huacai Chen

kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS

2023-06-05T00:50:44+00:00

When preprocessing arch/*/kernel/vmlinux.lds.S, the target triple is not passed to $(CPP) because we add it only to KBUILD_{C,A}FLAGS. As a result, the linker script is preprocessed with predefined macros for the build host instead of the target. Assuming you use an x86 build machine, compare the following: $ clang -dM -E -x c /dev/null $ clang -dM -E -x c /dev/null -target aarch64-linux-gnu There is no actual problem presumably because our linker scripts do not rely on such predefined macros, but it is better to define correct ones. Move $(CLANG_FLAGS) to KBUILD_CPPFLAGS, so that all *.c, *.S, *.lds.S will be processed with the proper target triple. [Note] After the patch submission, we got an actual problem that needs this commit. (CBL issue 1859) Link: https://github.com/ClangBuiltLinux/linux/issues/1859 Reported-by: Tom Rini Signed-off-by: Masahiro Yamada Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor

kbuild: clang: do not use CROSS_COMPILE for target triple

2023-04-17T02:23:06+00:00

The target triple is overridden by the user-supplied CROSS_COMPILE, but I do not see a good reason to support it. Users can use a new architecture without adding CLANG_TARGET_FLAGS_*, but that would be a rare case. Use the hard-coded and deterministic target triple all the time. Signed-off-by: Masahiro Yamada Acked-by: Nathan Chancellor Reviewed-by: Nick Desaulniers

kbuild: Turn a couple more of clang's unused option warnings into errors

2023-01-26T03:43:19+00:00

Currently, these warnings are hidden with -Qunused-arguments in KBUILD_CPPFLAGS. Once that option is removed, these warnings should be turned into hard errors to make unconditionally added but unsupported flags for the current compilation mode or target obvious due to a failed build; otherwise, the warnings might just be ignored if the build log is not checked. Link: https://github.com/ClangBuiltLinux/linux/issues/1587 Signed-off-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Tested-by: Linux Kernel Functional Testing Tested-by: Anders Roxell Signed-off-by: Masahiro Yamada

um: Allow builds with Clang

2022-03-21T15:13:03+00:00

Add SUBARCH target for Clang+um (which must go last, not alphabetically, so the other SUBARCHes are assigned). Remove open-coded "DEFINE" macro, instead using linux/kbuild.h's version which was updated to use Clang-friendly assembly in commit cf0c3e68aa81 ("kbuild: fix asm-offset generation to work with clang"). Redefine "DEFINE_LONGS" in terms of "COMMENT" and "DEFINE" so that the intended coment actually has useful content. Add a missed "break" to avoid implicit fall-through warnings. This lets me run KUnit tests with Clang: $ ./tools/testing/kunit/kunit.py run --make_options LLVM=1 ... Cc: Jeff Dike Cc: Richard Weinberger Cc: Anton Ivanov Cc: Masahiro Yamada Cc: Nick Desaulniers Cc: Nathan Chancellor Cc: David Gow Cc: linux-um@lists.infradead.org Cc: linux-kbuild@vger.kernel.org Cc: linux-kselftest@vger.kernel.org Cc: kunit-dev@googlegroups.com Cc: llvm@lists.linux.dev Reviewed-by: Nathan Chancellor Link: https://lore.kernel.org/lkml/Yg2YubZxvYvx7%2Fnm@dev-arch.archlinux-ax161/ Tested-by: David Gow Link: https://lore.kernel.org/lkml/CABVgOSk=oFxsbSbQE-v65VwR2+mXeGXDDjzq8t7FShwjJ3+kUg@mail.gmail.com/ Signed-off-by: Kees Cook --- v1: https://lore.kernel.org/lkml/20220217002843.2312603-1-keescook@chromium.org v2: https://lore.kernel.org/lkml/20220224055831.1854786-1-keescook@chromium.org v3: - use kbuild.h to avoid duplication (Masahiro) - fix intended comments (Masahiro) - use SUBARCH (Nathan)

kbuild: Add -Werror=ignored-optimization-argument to CLANG_FLAGS

2021-09-19T01:55:18+00:00

Similar to commit 589834b3a009 ("kbuild: Add -Werror=unknown-warning-option to CLANG_FLAGS"). Clang ignores certain GCC flags that it has not implemented, only emitting a warning: $ echo | clang -fsyntax-only -falign-jumps -x c - clang-14: warning: optimization flag '-falign-jumps' is not supported [-Wignored-optimization-argument] When one of these flags gets added to KBUILD_CFLAGS unconditionally, all subsequent cc-{disable-warning,option} calls fail because -Werror was added to these invocations to turn the above warning and the equivalent -W flag warning into errors. To catch the presence of these flags earlier, turn -Wignored-optimization-argument into an error so that the flags can either be implemented or ignored via cc-option and there are no more weird errors. Reviewed-by: Nick Desaulniers Signed-off-by: Nathan Chancellor Signed-off-by: Masahiro Yamada

kbuild: Switch to 'f' variants of integrated assembler flag

2021-09-02T23:17:20+00:00

It has been brought up a few times in various code reviews that clang 3.5 introduced -f{,no-}integrated-as as the preferred way to enable and disable the integrated assembler, mentioning that -{no-,}integrated-as are now considered legacy flags. Switch the kernel over to using those variants in case there is ever a time where clang decides to remove the non-'f' variants of the flag. Also, fix a typo in a comment ("intergrated" -> "integrated"). Link: https://releases.llvm.org/3.5.0/tools/clang/docs/ReleaseNotes.html#new-compiler-flags Reviewed-by: Nick Desaulniers Signed-off-by: Nathan Chancellor Signed-off-by: Masahiro Yamada