[PATCH] Makefile: fix build with binutils 2.38

[Anup Patel]

On Fri, Jan 28, 2022 at 11:04 PM Aurelien Jarno <aurelien at 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        lib/sbi/sbi_tlb.o
> <<BUILDDIR>>/lib/sbi/sbi_tlb.c: Assembler messages:
> <<BUILDDIR>>/lib/sbi/sbi_tlb.c:190: Error: unrecognized opcode `fence.i'
> make: *** [Makefile:431: <<BUILDDIR>>/build/lib/sbi/sbi_tlb.o] Error 1
>
> The fix is to specify those extensions explicitly in -march. However as
> older binutils version do not support this, we first need to detect
> that.
>
> Signed-off-by: Aurelien Jarno <aurelien at aurel32.net>

Looks good to me.

Reviewed-by: Anup Patel <anup at brainfault.org>

We will have to update docs/platform_requirements.md as well but
this can be a separate patch.

Regards,
Anup

> ---
>  Makefile | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> Changes v1 -> v2 following the review from Bin Men (thanks)!
> - Fix typos
> - Use grep to detect missing extensions for consistency with CC_SUPPORT_SAVE_RESTORE
>
> diff --git a/Makefile b/Makefile
> index 062883e..717dffd 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -153,6 +153,9 @@ OPENSBI_LD_PIE := $(shell $(CC) $(CLANG_TARGET) $(RELAX_FLAG) $(USE_LD_FLAG) -fP
>  # Check whether the compiler supports -m(no-)save-restore
>  CC_SUPPORT_SAVE_RESTORE := $(shell $(CC) $(CLANG_TARGET) $(RELAX_FLAG) -nostdlib -mno-save-restore -x c /dev/null -o /dev/null 2>&1 | grep "\-save\-restore" >/dev/null && echo n || echo y)
>
> +# Check whether the assembler and the compiler support the Zicsr and Zifencei extensions
> +CC_SUPPORT_ZICSR_ZIFENCEI := $(shell $(CC) $(CLANG_TARGET) $(RELAX_FLAG) -nostdlib -march=rv$(PLATFORM_RISCV_XLEN)imafd_zicsr_zifencei -x c /dev/null -o /dev/null 2>&1 | grep "zicsr\|zifencei" > /dev/null && echo n || echo y)
> +
>  # Build Info:
>  # OPENSBI_BUILD_TIME_STAMP -- the compilation time stamp
>  # OPENSBI_BUILD_COMPILER_VERSION -- the compiler version info
> @@ -223,7 +226,11 @@ ifndef PLATFORM_RISCV_ABI
>  endif
>  ifndef PLATFORM_RISCV_ISA
>    ifneq ($(PLATFORM_RISCV_TOOLCHAIN_DEFAULT), 1)
> -    PLATFORM_RISCV_ISA = rv$(PLATFORM_RISCV_XLEN)imafdc
> +    ifeq ($(CC_SUPPORT_ZICSR_ZIFENCEI), y)
> +      PLATFORM_RISCV_ISA = rv$(PLATFORM_RISCV_XLEN)imafdc_zicsr_zifencei
> +    else
> +      PLATFORM_RISCV_ISA = rv$(PLATFORM_RISCV_XLEN)imafdc
> +    endif
>    else
>      PLATFORM_RISCV_ISA = $(OPENSBI_CC_ISA)
>    endif
> --
> 2.34.1
>
>
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