On 2025-09-15 09:11:13+0200, Benjamin Berg wrote: > From: Benjamin Berg <benjamin.b...@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.b...@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); (...)
