# 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/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-gcc --version # < /opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-ld --version # < git log --format=%s --max-count=1 76426e238834f0927dee9925e8832179b8d56d6e # < make -s -j 48 ARCH=powerpc O=/kisskb/build/kbuild_corenet64_smp_defconfig+KVM_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- corenet64_smp_defconfig # Added to kconfig CONFIG_KVM_E500MC=y # Added to kconfig CONFIG_VIRTUALIZATION=y # Added to kconfig CONFIG_KVM_MPIC=y # < make -s -j 48 ARCH=powerpc O=/kisskb/build/kbuild_corenet64_smp_defconfig+KVM_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- help # make -s -j 48 ARCH=powerpc O=/kisskb/build/kbuild_corenet64_smp_defconfig+KVM_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- olddefconfig .config:4104:warning: override: reassigning to symbol VIRTUALIZATION # make -s -j 48 ARCH=powerpc O=/kisskb/build/kbuild_corenet64_smp_defconfig+KVM_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- /kisskb/src/fs/proc/inode.c: In function 'proc_reg_open': /kisskb/src/include/linux/list.h:72:12: warning: 'pdeo' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/proc/inode.c:471:21: note: 'pdeo' was declared here /kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl': /kisskb/src/kernel/printk/printk.c:204:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/ext4/extents.c: In function 'ext4_convert_unwritten_io_end_vec': /kisskb/src/fs/ext4/extents.c:4774:23: warning: 'ret' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/mm/hugetlb.c: In function 'alloc_pool_huge_page': /kisskb/src/mm/hugetlb.c:1741:5: warning: 'page' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/namei.c: In function 'handle_dots': /kisskb/src/fs/namei.c:1805:10: warning: 'inode' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/namei.c:1805:10: warning: 'seq' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/kernel/trace/trace_events.c: In function 'event_create_dir': /kisskb/src/kernel/trace/trace_events.c:2189:6: warning: 'ret' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/tty/serial/8250/8250_core.c: In function 'univ8250_release_irq': /kisskb/src/drivers/tty/serial/8250/8250_core.c:247:18: warning: 'i' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/tty/serial/8250/8250_core.c:227:19: note: 'i' was declared here /kisskb/src/fs/udf/unicode.c: In function 'udf_name_conv_char': /kisskb/src/fs/udf/unicode.c:132:8: warning: 'c' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/base/regmap/regmap.c: In function 'regmap_raw_read': /kisskb/src/drivers/base/regmap/regmap.c:2598:6: warning: 'ret' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/base/regmap/regmap.c: In function '_regmap_raw_write': /kisskb/src/drivers/base/regmap/regmap.c:1859:6: warning: 'ret' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/io_uring.c: In function '__io_sqe_files_update': /kisskb/src/fs/io_uring.c:6617:13: warning: 'err' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/usb/core/devio.c: In function 'async_completed': /kisskb/src/drivers/usb/core/devio.c:625:23: warning: 'errno' may be used uninitialized in this function [-Wuninitialized] WARNING: modpost: vmlinux.o (.PPC.EMB.apuinfo): unexpected non-allocatable section. Did you forget to use "ax"/"aw" in a .S file? Note that for example contains section definitions for use in .S files. INFO: Uncompressed kernel (size 0x1113270) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0x1200000) Image Name: Linux-5.6.0-13486-g76426e238834 Created: Thu Apr 9 01:32:57 2020 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 7138552 Bytes = 6971.24 KiB = 6.81 MiB Load Address: 00000000 Entry Point: 00000000 Completed OK # rm -rf /kisskb/build/kbuild_corenet64_smp_defconfig+KVM_powerpc-gcc4.6 # Build took: 0:01:50.326231