# git rev-parse -q --verify 76426e238834f0927dee9925e8832179b8d56d6e^{commit} 76426e238834f0927dee9925e8832179b8d56d6e already have revision, skipping fetch # git checkout -q -f -B kisskb 76426e238834f0927dee9925e8832179b8d56d6e # git clean -qxdf # < git log -1 # commit 76426e238834f0927dee9925e8832179b8d56d6e # Author: Masahiro Yamada # Date: Wed Apr 8 00:53:52 2020 +0900 # # kbuild: add dummy toolchains to enable all cc-option etc. in Kconfig # # Staring v4.18, Kconfig evaluates compiler capabilities, and hides CONFIG # options your compiler does not support. This works well if you configure # and build the kernel on the same host machine. # # It is inconvenient if you prepare the .config that is carried to a # different build environment (typically this happens when you package # the kernel for distros) because using a different compiler potentially # produces different CONFIG options than the real build environment. # So, you probably want to make as many options visible as possible. # In other words, you need to create a super-set of CONFIG options that # cover any build environment. If some of the CONFIG options turned out # to be unsupported on the build machine, they are automatically disabled # by the nature of Kconfig. # # However, it is not feasible to get a full-featured compiler for every # arch. # # This issue was discussed here: # # https://lkml.org/lkml/2019/12/9/620 # # Other than distros, savedefconfig is also a problem. Some arch sub-systems # periodically resync defconfig files. If you use a less-capable compiler # for savedefconfig, options that do not meet 'depends on $(cc-option,...)' # will be forcibly disabled. So, 'make defconfig && make savedefconfig' # may silently change the behavior. # # This commit adds a set of dummy toolchains that pretend to support any # feature. # # Most of compiler features are tested by cc-option, which simply checks # the exit code of $(CC). The dummy tools are shell scripts that always # exit with 0. So, $(cc-option, ...) is evaluated as 'y'. # # There are more complicated checks such as: # # scripts/gcc-x86_{32,64}-has-stack-protector.sh # scripts/gcc-plugin.sh # scripts/tools-support-relr.sh # # scripts/dummy-tools/gcc passes all checks. # # From the top directory of the source tree, you can do: # # $ make CROSS_COMPILE=scripts/dummy-tools/ oldconfig # # Signed-off-by: Masahiro Yamada # Reviewed-by: Philipp Rudo # Tested-by: Jeremy Cline # < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version # < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version # < git log --format=%s --max-count=1 76426e238834f0927dee9925e8832179b8d56d6e # < make -s -j 48 ARCH=powerpc O=/kisskb/build/kbuild_powernv_defconfig+NO_PERF_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- powernv_defconfig # Added to kconfig CONFIG_PERF_EVENTS=n # < make -s -j 48 ARCH=powerpc O=/kisskb/build/kbuild_powernv_defconfig+NO_PERF_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- help # make -s -j 48 ARCH=powerpc O=/kisskb/build/kbuild_powernv_defconfig+NO_PERF_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- olddefconfig # make -s -j 48 ARCH=powerpc O=/kisskb/build/kbuild_powernv_defconfig+NO_PERF_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- /kisskb/src/kernel/trace/ftrace.c: In function 'pid_open': /kisskb/src/kernel/trace/ftrace.c:7166:6: warning: 'seq_ops' may be used uninitialized in this function [-Wmaybe-uninitialized] ret = seq_open(file, seq_ops); ^ /kisskb/src/kernel/trace/ftrace.c: In function 'pid_write': /kisskb/src/kernel/trace/ftrace.c:7244:8: warning: 'filtered_pids' may be used uninitialized in this function [-Wmaybe-uninitialized] ret = trace_pid_write(filtered_pids, &pid_list, ubuf, cnt); ^ /kisskb/src/kernel/trace/ftrace.c:7261:22: warning: 'other_pids' may be used uninitialized in this function [-Wmaybe-uninitialized] } else if (pid_list && !other_pids) { ^ WARNING: modpost: vmlinux.o(.text.unlikely+0x1a0): Section mismatch in reference from the function early_init_mmu() to the function .init.text:radix__early_init_mmu() The function early_init_mmu() references the function __init radix__early_init_mmu(). This is often because early_init_mmu lacks a __init annotation or the annotation of radix__early_init_mmu is wrong. WARNING: modpost: vmlinux.o(.text.unlikely+0x1ac): Section mismatch in reference from the function early_init_mmu() to the function .init.text:hash__early_init_mmu() The function early_init_mmu() references the function __init hash__early_init_mmu(). This is often because early_init_mmu lacks a __init annotation or the annotation of hash__early_init_mmu is wrong. Completed OK # rm -rf /kisskb/build/kbuild_powernv_defconfig+NO_PERF_powerpc-gcc5 # Build took: 0:02:57.331182