Hello, Commit 0b2d3dafc0d3 ("libcflat: provide long division routines"), which added the lib/ldiv32.c file, breaks compilation for the arm architecture; arm64 seems to be working just fine. On Arch Linux: $ ./configure --arch=arm --cross-prefix=arm-none-eabi- $ make clean && make rm -f lib/arm/asm-offsets.h lib/arm/asm-offsets.s \ lib/generated/asm-offsets.h rm -f arm/*.{o,flat,elf} lib/arm/libeabi.a lib/arm/eabi_compat.o \ arm/.*.d lib/arm/.*.d CLEAN (libfdt) rm -f lib/libfdt/*.o lib/libfdt/.*.d rm -f lib/libfdt/libfdt.so.1 rm -f lib/libfdt/libfdt.a rm -f lib/.*.d lib/libcflat.a lib/argv.o lib/printf.o lib/string.o lib/abort.o lib/report.o lib/stack.o lib/arm/spinlock.o lib/arm/processor.o lib/arm/stack.o lib/ldiv32.o lib/util.o lib/getchar.o lib/alloc_phys.o lib/alloc_page.o lib/vmalloc.o lib/alloc.o lib/devicetree.o lib/pci.o lib/pci-host-generic.o lib/pci-testdev.o lib/virtio.o lib/virtio-mmio.o lib/chr-testdev.o lib/arm/io.o lib/arm/setup.o lib/arm/mmu.o lib/arm/bitops.o lib/arm/psci.o lib/arm/smp.o lib/arm/delay.o lib/arm/gic.o lib/arm/gic-v2.o lib/arm/gic-v3.o [..] arm-none-eabi-gcc -marm -mfpu=vfp -mcpu=cortex-a15 -mno-unaligned-access -std=gnu99 -ffreestanding -O2 -I /home/alex/data/repos/kvm-unit-tests/lib -I /home/alex/data/repos/kvm-unit-tests/lib/libfdt -I lib -g -MMD -MF lib/.ldiv32.d -fno-strict-aliasing -fno-common -Wall -Wwrite-strings -Wempty-body -Wuninitialized -Wignored-qualifiers -Werror -fno-omit-frame-pointer -fno-stack-protector -Wno-frame-address -D__U32_LONG_FMT__ -fno-pic -no-pie -Wclobbered -Wunused-but-set-parameter -Wmissing-parameter-type -Wold-style-declaration -Woverride-init -Wmissing-prototypes -Wstrict-prototypes -c -o lib/ldiv32.o lib/ldiv32.c lib/ldiv32.c: In function '__moddi3': lib/ldiv32.c:73:11: error: 'rem' may be used uninitialized in this function [-Werror=maybe-uninitialized] 73 | uint64_t rem; | ^~~ lib/ldiv32.c: In function '__umoddi3': lib/ldiv32.c:75:9: error: 'rem' may be used uninitialized in this function [-Werror=maybe-uninitialized] 75 | return rem; | ^~~ cc1: all warnings being treated as errors make: *** [<builtin>: lib/ldiv32.o] Error 1 $ arm-none-eabi-gcc --version arm-none-eabi-gcc (Arch Repository) 10.3.0 Copyright (C) 2020 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. On Fedora 33: $ ./configure --arch=arm --cross-prefix=arm-linux-gnu- $ make clean && make rm -f lib/arm/asm-offsets.h lib/arm/asm-offsets.s \ lib/generated/asm-offsets.h rm -f arm/*.{o,flat,elf} lib/arm/libeabi.a lib/arm/eabi_compat.o \ arm/.*.d lib/arm/.*.d CLEAN (libfdt) rm -f lib/libfdt/*.o lib/libfdt/.*.d rm -f lib/libfdt/libfdt.so.1 rm -f lib/libfdt/libfdt.a rm -f lib/.*.d lib/libcflat.a lib/argv.o lib/printf.o lib/string.o lib/abort.o lib/report.o lib/stack.o lib/arm/spinlock.o lib/arm/processor.o lib/arm/stack.o lib/ldiv32.o lib/util.o lib/getchar.o lib/alloc_phys.o lib/alloc_page.o lib/vmalloc.o lib/alloc.o lib/devicetree.o lib/pci.o lib/pci-host-generic.o lib/pci-testdev.o lib/virtio.o lib/virtio-mmio.o lib/chr-testdev.o lib/arm/io.o lib/arm/setup.o lib/arm/mmu.o lib/arm/bitops.o lib/arm/psci.o lib/arm/smp.o lib/arm/delay.o lib/arm/gic.o lib/arm/gic-v2.o lib/arm/gic-v3.o [..] arm-linux-gnu-gcc -marm -mfpu=vfp -mcpu=cortex-a15 -mno-unaligned-access -std=gnu99 -ffreestanding -O2 -I /home/alex/data/repos/kvm-unit-tests/lib -I /home/alex/data/repos/kvm-unit-tests/lib/libfdt -I lib -g -MMD -MF lib/.ldiv32.d -fno-strict-aliasing -fno-common -Wall -Wwrite-strings -Wempty-body -Wuninitialized -Wignored-qualifiers -Werror -fno-omit-frame-pointer -fno-stack-protector -Wno-frame-address -fno-pic -no-pie -Wclobbered -Wunused-but-set-parameter -Wmissing-parameter-type -Wold-style-declaration -Woverride-init -Wmissing-prototypes -Wstrict-prototypes -c -o lib/ldiv32.o lib/ldiv32.c lib/ldiv32.c:1:10: fatal error: inttypes.h: No such file or directory 1 | #include <inttypes.h> | ^~~~~~~~~~~~ compilation terminated. make: *** [<builtin>: lib/ldiv32.o] Error 1 $ arm-linux-gnu-gcc --version arm-linux-gnu-gcc (GCC) 10.2.1 20200826 (Red Hat Cross 10.2.1-3) Copyright (C) 2020 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Reverting the commit makes arm build again. I am not familiar with toolchains, and unfortunately I can't propose a fix. Thanks, Alex