[PATCH] riscv: Fix build against binutils 2.38

[Heiko Stübner]

Am Freitag, 28. Januar 2022, 14:47:13 CEST schrieb Alexandre Ghiti:
> The following description is copied from the equivalent patch for the
> Linux Kernel proposed by Aurelien Jarno:
> 
> 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:
> 
> arch/riscv/cpu/mtrap.S: Assembler messages:
> arch/riscv/cpu/mtrap.S:65: Error: unrecognized opcode `csrr a0,scause'
> arch/riscv/cpu/mtrap.S:66: Error: unrecognized opcode `csrr a1,sepc'
> arch/riscv/cpu/mtrap.S:67: Error: unrecognized opcode `csrr a2,stval'
> arch/riscv/cpu/mtrap.S:70: Error: unrecognized opcode `csrw sepc,a0'
> 
> Signed-off-by: Alexandre Ghiti <alexandre.ghiti at canonical.com>

After upgrading my binutils to the recent snapshot package
in Debian-unstable (2.38.50.20220622-1), I've also run into that issue:

/home/devel/hstuebner/04_riscv/sun20i_d1_u-boot/drivers/timer/riscv_timer.c: Assembler messages:
/home/devel/hstuebner/04_riscv/sun20i_d1_u-boot/drivers/timer/riscv_timer.c:24: Error: unrecognized opcode `csrr a0,0xc01', extension `zicsr' required
make[3]: *** [/home/devel/hstuebner/04_riscv/sun20i_d1_u-boot/scripts/Makefile.build:254: drivers/timer/riscv_timer.o] Fehler 1


Is there progress in getting this patch applied to u-boot in some way?
Also it looks like there was another patch with similar content submitted
recently [0].


In any case:

On a D1-Nezha it fixes the build (and boot)
Tested-by: Heiko Stuebner <heiko at sntech.de>


Thanks
Heiko


[0] https://lore.kernel.org/all/PH7PR14MB5594FD11D1BE74284F554BEBCED49@PH7PR14MB5594.namprd14.prod.outlook.com/

> ---
>  arch/riscv/Makefile | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> index 0b80eb8d86..53d1194ffb 100644
> --- a/arch/riscv/Makefile
> +++ b/arch/riscv/Makefile
> @@ -24,7 +24,16 @@ ifeq ($(CONFIG_CMODEL_MEDANY),y)
>  	CMODEL = medany
>  endif
>  
> -ARCH_FLAGS = -march=$(ARCH_BASE)$(ARCH_A)$(ARCH_C) -mabi=$(ABI) \
> +RISCV_MARCH = $(ARCH_BASE)$(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=$(RISCV_MARCH)_zicsr_zifencei)
> +ifeq ($(toolchain-need-zicsr-zifencei),y)
> +	RISCV_MARCH := $(RISCV_MARCH)_zicsr_zifencei
> +endif
> +
> +ARCH_FLAGS = -march=$(RISCV_MARCH) -mabi=$(ABI) \
>  	     -mcmodel=$(CMODEL)
>  
>  PLATFORM_CPPFLAGS	+= $(ARCH_FLAGS)
>