Building userspace applications through the kbuild "userprogs" framework requires a libc. Kernel toolchains often do not contain a libc. In this case it is useful to use the nolibc library from the kernel tree. Nolibc does not support all architectures and requires compiler flags.
Add a kconfig option, so users can know where it is available and provide a variable for common options. Reviewed-by: Nicolas Schier <[email protected]> Signed-off-by: Thomas Weißschuh <[email protected]> --- MAINTAINERS | 2 ++ init/Kconfig | 2 ++ init/Kconfig.nolibc | 15 +++++++++++++++ init/Makefile.nolibc | 13 +++++++++++++ 4 files changed, 32 insertions(+) diff --git a/MAINTAINERS b/MAINTAINERS index a92290fffa163f9fe8fe3f04bf66426f9a894409..e806158cc6798cf97a4aab58c038fb5351d469aa 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -17702,6 +17702,8 @@ M: Willy Tarreau <[email protected]> M: Thomas Weißschuh <[email protected]> S: Maintained T: git git://git.kernel.org/pub/scm/linux/kernel/git/nolibc/linux-nolibc.git +F: init/Kconfig.nolibc +F: init/Makefile.nolibc F: tools/include/nolibc/ F: tools/testing/selftests/nolibc/ diff --git a/init/Kconfig b/init/Kconfig index 26cafbad4f1560fb56b4bef31ae29baf54175661..0af62f135192e0470e16eb6bb2fbb45ac38f4b81 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -92,6 +92,8 @@ config CC_CAN_LINK_STATIC default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static) +source "init/Kconfig.nolibc" + # Fixed in GCC 14, 13.3, 12.4 and 11.5 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921 config GCC_ASM_GOTO_OUTPUT_BROKEN diff --git a/init/Kconfig.nolibc b/init/Kconfig.nolibc new file mode 100644 index 0000000000000000000000000000000000000000..29cbc5437e70cbc5e256f00b74d0ab4801b40de7 --- /dev/null +++ b/init/Kconfig.nolibc @@ -0,0 +1,15 @@ +# SPDX-License-Identifier: GPL-2.0 + +config ARCH_HAS_NOLIBC + bool + default y if ARM + default y if ARM64 + default y if LOONGARCH + default y if M68K + default y if MIPS + default y if PPC + default y if RISCV + default y if S390 + default y if SPARC + default y if UML_X86 + default y if X86 diff --git a/init/Makefile.nolibc b/init/Makefile.nolibc new file mode 100644 index 0000000000000000000000000000000000000000..dacc78ab4c81c93f3a24ebeb70e34253842f9a53 --- /dev/null +++ b/init/Makefile.nolibc @@ -0,0 +1,13 @@ +# SPDX-License-Identifier: GPL-2.0 +# Compiler flags, which are necessary to build userspace applications with the +# in-kernel libc "nolibc". + +ifeq ($(and $(CONFIG_ARCH_HAS_NOLIBC),$(CONFIG_HEADERS_INSTALL)),y) + +NOLIBC_USERCFLAGS := -nostdlib -nostdinc -static -ffreestanding \ + -fno-asynchronous-unwind-tables -fno-stack-protector \ + -I$(objtree)/usr/include -I$(srctree)/tools/include/nolibc/ + +NOLIBC_USERLDFLAGS := -nostdlib -nostdinc -static + +endif # CONFIG_ARCH_HAS_NOLIBC && CONFIG_HEADERS_INSTALL -- 2.50.0
