Re: [PATCH] riscv: fix compitible with binutils 2.38

["Heiko Stübner" <heiko@sntech.de>]

Hi,

Am Montag, 23. Mai 2022, 14:05:27 CEST schrieb Coelacanthus:
> commit 6df2a016c0c8a3d0933ef33dd192ea6606b115e3 from linux kernel
> 
> Since binutils 2.38, default ISA spec version switch to 20191213,
> in this version, original I extension be split into I, Zicsr and Zifencei.
> Zicsr is csr read/write (csrr*/csrw*) instructions, and Zifencei
> is fence.i instruction.
> This will cause compile error like this:
>     Error: unrecognized opcode `csrr a5,0xc01'
>     Error: unrecognized opcode `fence.i'
> 
> This commit add code to detect new Zicsr and Zifencei extensions,
> and enable it when needed.
> 
> Signed-off-by: Coelacanthus <coelacanthus@outlook.com>
> Cc: Rick Chen <rick@andestech.com>
> Cc: Leo <ycliang@andestech.com>

while this fixes the build issue I'm seeing after a recent binutils,
there has been already a patch proposed for this fix [0]
and in that thread some pending issue was discussed as well.

So please coordinate with the other people over there :-)


Thanks
Heiko

[0] https://lore.kernel.org/all/20220128134713.2322800-1-alexandre.ghiti@canonical.com/

> ---
>  arch/riscv/Makefile | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> index 0b80eb8d86..62712f8d38 100644
> --- a/arch/riscv/Makefile
> +++ b/arch/riscv/Makefile
> @@ -24,7 +24,14 @@ ifeq ($(CONFIG_CMODEL_MEDANY),y)
>  	CMODEL = medany
>  endif
>  
> -ARCH_FLAGS = -march=$(ARCH_BASE)$(ARCH_A)$(ARCH_C) -mabi=$(ABI) \
> +RISCV_MARCH_y = $(ARCH_BASE)$(ARCH_A)$(ARCH_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 := $(call cc-option-yn, -mabi=$(ABI) -march=$(RISCV_MARCH_y)_zicsr_zifencei)
> +RISCV_MARCH_$(toolchain-need-zicsr-zifencei) := $(RISCV_MARCH_y)_zicsr_zifencei
> +
> +ARCH_FLAGS = -march=$(RISCV_MARCH_y) -mabi=$(ABI) \
>  	     -mcmodel=$(CMODEL)
>  
>  PLATFORM_CPPFLAGS	+= $(ARCH_FLAGS)
>