Re: [PATCH v7 03/19] xen/riscv: introduce extenstion support check by compiler

[Jan Beulich <jbeulich@xxxxxxxx>]

On 03.04.2024 12:19, Oleksii Kurochko wrote:
> Currently, RISC-V requires two extensions: _zbb and _zihintpause.
> 
> This patch introduces a compiler check to check if these extensions
> are supported.
> Additionally, it introduces the riscv/booting.txt file, which contains
> information about the extensions that should be supported by the platform.
> 
> In the future, a feature will be introduced to check whether an extension
> is supported at runtime.
> However, this feature requires functionality for parsing device tree
> source (DTS), which is not yet available.
> 
> Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>

Acked-by: Jan Beulich <jbeulich@xxxxxxxx>

However, ...

> --- a/xen/arch/riscv/arch.mk
> +++ b/xen/arch/riscv/arch.mk
> @@ -3,16 +3,27 @@
>  
>  $(call cc-options-add,CFLAGS,CC,$(EMBEDDED_EXTRA_CFLAGS))
>  
> -CFLAGS-$(CONFIG_RISCV_64) += -mabi=lp64
> +riscv-abi-$(CONFIG_RISCV_32) := -mabi=ilp32
> +riscv-abi-$(CONFIG_RISCV_64) := -mabi=lp64
>  
>  riscv-march-$(CONFIG_RISCV_ISA_RV64G) := rv64g
>  riscv-march-$(CONFIG_RISCV_ISA_C)       := $(riscv-march-y)c
>  
> +riscv-generic-flags := $(riscv-abi-y) -march=$(riscv-march-y)
> +
> +zbb := $(call as-insn,$(CC) $(riscv-generic-flags)_zbb,"",_zbb)
> +zihintpause := $(call as-insn,\
> +               $(CC) $(riscv-generic-flags)_zihintpause,"pause",_zihintpause)

... this would better be indented thus

zihintpause := $(call as-insn, \
                      $(CC) 
$(riscv-generic-flags)_zihintpause,"pause",_zihintpause)

to make nesting entirely obvious. I guess I'll table the liberty to adjust
while committing.

I'd also like to note that this is specifically not what I had suggested.
But it at least improves readability.

Jan