We get constant feedback that the command line invocation of make is too long. CROSS_COMPILE is helpful when a toolchain has a prefix of the target triple, or is an absolute path outside of $PATH, but it's mostly redundant for a given ARCH. Instead, let's infer --target from SRCARCH, and move some flag handling into a new file included from the top level Makefile. Changes v5 -> v6: * Use indirection as per Linus. * Change hexagon triple to use -musl rather than -gnu. glibc doesn't have support for hexagon, and hexagon-linux-musl is the triple we use in CI. https://github.com/ClangBuiltLinux/continuous-integration2/blob/d659897d1700894d67feb64fe28e298da399a287/generator.yml#L53 * Pick up Fangrui's RB. * Reorder use of Env vars in documentation to use command line parameters instead, for consistency. Changes v4 -> v5: * Include previously missing first patch! Changes v3 -> v4: * Remove the requirement that LLVM_IAS=1 be set, as per Masahiro. * Remove the Documentation/ change from patch 2, as per Masahiro and Nathan. * Add Documentation/ change as patch 3, from Masahiro. * Reword commit message of patch 2, as per Nathan. * Change patch 2 oneline to refer to --target and CC=clang (not CROSS_COMPILE). * Carry Arnd's and Nathan's AB/RB/TB tags, confirmed ok on IRC+discord. Changes v2 -> v3: * Remove requirement that LLVM=1 be set. Instead, if building with just CC=clang LLVM_IAS=1 instead of LLVM=1 LLVM_IAS=1, you should use LD=ld.lld explicitly, or LD=aarch64-linux-gnu-ld. (As per Masahiro) Example: $ ARCH=arm64 make CC=clang LLVM_IAS=1 LD=ld.lld OBJCOPY=llvm-objcopy \ STRIP=llvm-strip -j72 defconfig all (It's still preferable to use LLVM=1 IMO, but this is maximally flexible.) * Change oneliner from LLVM=1 to CC=clang. * Update Docs slightly. Changes v1 -> v2: * patch 1/2 untouched. * Fix typos in commit message as per Geert and Masahiro. * Use SRCARCH instead of ARCH, simplifying x86 handling, as per Masahiro. Add his sugguested by tag. * change commit oneline from 'drop' to 'infer.' * Add detail about explicit host --target and relationship of ARCH to SRCARCH, as per Masahiro. Nick Desaulniers (3): Makefile: move initial clang flag handling into scripts/Makefile.clang Makefile: infer --target from ARCH for CC=clang Documentation/llvm: update CROSS_COMPILE inferencing Documentation/kbuild/llvm.rst | 19 ++++++++++++++++++- MAINTAINERS | 1 + Makefile | 15 +-------------- scripts/Makefile.clang | 35 +++++++++++++++++++++++++++++++++++ 4 files changed, 55 insertions(+), 15 deletions(-) create mode 100644 scripts/Makefile.clang base-commit: d7a86429dbc691bf540688fcc8542cc20246a85b -- 2.32.0.554.ge1b32706d8-goog
