On 2025-09-15 09:11:13+0200, Benjamin Berg wrote:
From: Benjamin Berg benjamin.berg@intel.com
Add NOLIBC_CFLAGS and NOLIBC_OBJS to build files against nolibc rather than libc. With this it is possible to move to nolibc in smaller steps.
Set NOLIBC_IGNORE_ERRNO, as the nolibc errno implementation is overly simple and cannot handle threading. nolibc provides sys_* functions that do not emulate the libc errno behaviour and can be used instead.
Guard the syscall definition as it is a macro in nolibc.
Signed-off-by: Benjamin Berg benjamin.berg@intel.com
arch/um/Makefile | 21 ++++++++++++++++++++- arch/um/include/shared/os.h | 2 ++ arch/um/scripts/Makefile.rules | 8 +++++++- 3 files changed, 29 insertions(+), 2 deletions(-)
diff --git a/arch/um/Makefile b/arch/um/Makefile index a3f27d791cc0..54aa26fcc32b 100644 --- a/arch/um/Makefile +++ b/arch/um/Makefile @@ -78,6 +78,25 @@ USER_CFLAGS = $(patsubst $(KERNEL_DEFINES),,$(patsubst -I%,,$(KBUILD_CFLAGS))) \ -include $(srctree)/include/linux/kern_levels.h \ -include $(srctree)/$(ARCH_DIR)/include/shared/user.h +NOLIBC_CFLAGS = $(patsubst $(KERNEL_DEFINES),,$(patsubst -I%,,$(KBUILD_CFLAGS))) \
$(ARCH_INCLUDE) $(MODE_INCLUDE) $(filter -I%,$(CFLAGS)) \-I $(srctree)/tools/include \-D__EXPORTED_HEADERS__ \-D__UM_HOST__ -D__UM_NOLIBC__ \-DNOLIBC_NO_STARTCODE \-DNOLIBC_IGNORE_ERRNO \-nostdlib -nostdinc -static \-I$(srctree)/include/uapi \-I$(srctree)/$(HOST_DIR)/include/uapi \-I$(objtree)/$(HOST_DIR)/include/generated/uapi \-I $(srctree)/tools/include/nolibc \-I $(srctree)/usr/include \-include $(srctree)/include/generated/autoconf.h \-include $(srctree)/tools/include/linux/kconfig.h \-include $(srctree)/include/linux/kern_levels.h \-include $(srctree)/tools/include/nolibc/nolibc.h \
This is not needed. It doesn't hurt though.
-include $(srctree)/$(ARCH_DIR)/include/shared/user.h#This will adjust *FLAGS accordingly to the platform. include $(srctree)/$(ARCH_DIR)/Makefile-os-Linux @@ -157,4 +176,4 @@ archclean: -o -name '*.gcov' ) -type f -print | xargs rm -f $(Q)$(MAKE) -f $(srctree)/Makefile ARCH=$(HEADER_ARCH) clean -export HEADER_ARCH SUBARCH USER_CFLAGS CFLAGS_NO_HARDENING DEV_NULL_PATH +export HEADER_ARCH SUBARCH USER_CFLAGS NOLIBC_CFLAGS CFLAGS_NO_HARDENING DEV_NULL_PATH diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h index b35cc8ce333b..3e9f3ae61658 100644 --- a/arch/um/include/shared/os.h +++ b/arch/um/include/shared/os.h @@ -327,7 +327,9 @@ extern int __ignore_sigio_fd(int fd); /* tty.c */ extern int get_pty(void); +#ifndef syscall
You could use 'ifndef NOLIBC' to make the reason clear.
long syscall(long number, ...); +#endif /* irqflags tracing */ extern void block_signals_trace(void);
(...)