[PATCH] Makefile: fix build with binutils 2.38

[Xiang W]

在 2022-01-28星期五的 18:33 +0100，Aurelien Jarno写道：
> 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:
The latest version of GNU binutils is 2.37. 2.38 should not be released
yet, are there any new patch references for these changes?

Regards,
Xiang W
> 
>  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>
> ---
>  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
> 
>