On Thursday, October 27, 2016 11:11:18 AM CEST Thomas Petazzoni wrote: > On Thu, 27 Oct 2016 09:07:55 +0000, Alexey Brodkin wrote: > > > > axs101 is using a 770 core, while the toolchain is built for the HS38 > > > core. I'm somewhat surprised that a single ARC toolchain cannot produce > > > code for both 770 and HS38, but it seems to be the case. > > > > > > So you need a separate toolchain for ARC770. > > > > Indeed axs101 uses ARC770 core which is ARCv1 AKA ARCompact ISA while > > axs103 sports the same base-board but CPU daughter-card contains ARC HS38 core > > which has ARCv2 ISA (binary incompatible with ARCompact). > > > > Essentially both gcc and binutils will happily build for both architectures given > > proper options were passed on the command line. But Linux kernel gets linked with > > pre-built libgcc (it is a part of toolchain). And so it all boils down to a requirement > > to have multilibbed uClibc toolchain. Which we don't have. > > Interesting. Why is libgcc linked with the kernel on ARC? I don't think > that's the case on other architectures: the kernel is freestanding and > provides everything that it needs without relying on the compiler > runtime. A couple of other architectures do this as well: $ git grep -w LIBGCC arch/*/Makefile arch/arc/Makefile:LIBGCC := $(shell $(CC) $(cflags-y) --print-libgcc-file-name) arch/arc/Makefile:libs-y += arch/arc/lib/ $(LIBGCC) arch/cris/Makefile:LIBGCC = $(shell $(CC) $(KBUILD_CFLAGS) -print-file-name=libgcc.a) arch/cris/Makefile:libs-y += arch/cris/$(SARCH)/lib/ $(LIBGCC) arch/hexagon/Makefile:LIBGCC := $(shell $(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name) arch/hexagon/Makefile:libs-y += $(LIBGCC) arch/m32r/Makefile:LIBGCC := $(shell $(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name) arch/m32r/Makefile:libs-y += arch/m32r/lib/ $(LIBGCC) arch/nios2/Makefile:LIBGCC := $(shell $(CC) $(KBUILD_CFLAGS) $(KCFLAGS) -print-libgcc-file-name) arch/nios2/Makefile:libs-y += arch/nios2/lib/ $(LIBGCC) arch/openrisc/Makefile:LIBGCC := $(shell $(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name) arch/openrisc/Makefile:libs-y += $(LIBGCC) arch/parisc/Makefile:LIBGCC = $(shell $(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name) arch/parisc/Makefile:libs-y += arch/parisc/lib/ $(LIBGCC) arch/xtensa/Makefile:LIBGCC := $(shell $(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name) arch/xtensa/Makefile:libs-y += arch/xtensa/lib/ $(LIBGCC) It's also not always freestanding on the architectures that don't include libgcc: $ git grep ffreestanding arch/ arch/mips/Makefile:cflags-y += -ffreestanding arch/s390/boot/compressed/Makefile:KBUILD_CFLAGS += $(call cc-option,-ffreestanding) arch/score/Makefile: -D__linux__ -ffunction-sections -ffreestanding arch/sh/Makefile:cflags-y += $(isaflags-y) -ffreestanding arch/x86/Makefile: KBUILD_CFLAGS += -ffreestanding # temporary until string.h is fixed arch/xtensa/Makefile:KBUILD_CFLAGS += -ffreestanding -D__linux__ (xtensa being the only one that apparently uses libgcc *and* passes -ffreestanding, for whatever reasons). The other architectures tend to implement the parts of libgcc that they need in the kernel. Arnd
