Messages in this thread | | | Date | Thu, 10 Feb 2022 09:40:22 -0800 (PST) | Subject | Re: [PATCH] riscv: fix build with binutils 2.38 | From | Palmer Dabbelt <> |
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On Wed, 26 Jan 2022 09:14:42 PST (-0800), aurelien@aurel32.net wrote: > From version 2.38, binutils default to ISA spec version 20191213. This > means that the csr read/write (csrr*/csrw*) instructions and fence.i > instruction has separated from the `I` extension, become two standalone > extensions: Zicsr and Zifencei. As the kernel uses those instruction, > this causes the following build failure: > > CC arch/riscv/kernel/vdso/vgettimeofday.o > <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h: Assembler messages: > <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h:71: Error: unrecognized opcode `csrr a5,0xc01' > <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h:71: Error: unrecognized opcode `csrr a5,0xc01' > <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h:71: Error: unrecognized opcode `csrr a5,0xc01' > <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h:71: Error: unrecognized opcode `csrr a5,0xc01' > > The fix is to specify those extensions explicitely in -march. However as > older binutils version do not support this, we first need to detect > that. > > Cc: stable@vger.kernel.org # 4.15+ > Cc: Kito Cheng <kito.cheng@gmail.com> > Signed-off-by: Aurelien Jarno <aurelien@aurel32.net> > --- > arch/riscv/Makefile | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile > index 8a107ed18b0d..7d81102cffd4 100644 > --- a/arch/riscv/Makefile > +++ b/arch/riscv/Makefile > @@ -50,6 +50,12 @@ riscv-march-$(CONFIG_ARCH_RV32I) := rv32ima > riscv-march-$(CONFIG_ARCH_RV64I) := rv64ima > riscv-march-$(CONFIG_FPU) := $(riscv-march-y)fd > riscv-march-$(CONFIG_RISCV_ISA_C) := $(riscv-march-y)c > + > +# Newer binutils versions default to ISA spec version 20191213 which moves some > +# instructions from the I extension to the Zicsr and Zifencei extensions. > +toolchain-need-zicsr-zifencei := $(call cc-option-yn, -march=$(riscv-march-y)_zicsr_zifencei) > +riscv-march-$(toolchain-need-zicsr-zifencei) := $(riscv-march-y)_zicsr_zifencei > + > KBUILD_CFLAGS += -march=$(subst fd,,$(riscv-march-y)) > KBUILD_AFLAGS += -march=$(riscv-march-y)
Thanks, this is on fixes. It's CC stable, but doesn't have a "Fixes" tag -- I did that on purpose as this isn't really fixing a bug in Linux so I'm not sure it's right to point at a particular patch, but I'm not sure how that will play with the stable tree.
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