[PATCH 1/1] riscv: support building double-float modules

[Rick Chen]

> From: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> Sent: Saturday, October 08, 2022 5:18 PM
> To: Rick Jian-Zhi Chen(陳建志) <rick at andestech.com>; Leo Yu-Chi Liang(梁育齊) <ycliang at andestech.com>
> Cc: Tom Rini <trini at konsulko.com>; u-boot at lists.denx.de; Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> Subject: [PATCH 1/1] riscv: support building double-float modules
>
> The riscv32 toolchain for GCC-12 provided by kernel.org contains libgcc.a compiled for double-float. To link to it we have to adjust how we build U-Boot.
>
> As U-Boot actually does not use floating point at all this should not make a significant difference for the produced binaries.
>
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> ---
>  arch/riscv/Kconfig  | 14 ++++++++++++++  arch/riscv/Makefile | 17 ++++++++++++++---
>  2 files changed, 28 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 32a90b83b5..8add95c8ef 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -152,6 +152,20 @@ config RISCV_ISA_C
>           when building U-Boot, which results in compressed instructions in the
>           U-Boot binary.
>
> +config RISCV_ISA_F
> +       bool "Standard extension for Single-Precision Floating Point"
> +       default y


Shall this default y need to depend on RV32 ?

Reviewed-by: Rick Chen <rick at andestech.com>

> +       help
> +         Adds "F" to the ISA string passed to the compiler.
> +
> +config RISCV_ISA_D
> +       bool "Standard extension forr Double-Precision Floating Point"
> +       depends on RISCV_ISA_F
> +       default y
> +       help
> +         Adds "D" to the ISA string passed to the compiler and changes the
> +         riscv32 ABI from ilp32 to ipl32d.
> +
>  config RISCV_ISA_A
>         def_bool y
>
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index 53d1194ffb..d1b6e86dd8 100644
> --- a/arch/riscv/Makefile
> +++ b/arch/riscv/Makefile
> @@ -5,15 +5,24 @@
>
>  ifeq ($(CONFIG_ARCH_RV64I),y)
>         ARCH_BASE = rv64im
> -       ABI = lp64
> +       ABI_BASE = lp64
>  endif
>  ifeq ($(CONFIG_ARCH_RV32I),y)
>         ARCH_BASE = rv32im
> -       ABI = ilp32
> +       ABI_BASE = ilp32
>  endif
>  ifeq ($(CONFIG_RISCV_ISA_A),y)
>         ARCH_A = a
>  endif
> +ifeq ($(CONFIG_RISCV_ISA_F),y)
> +       ARCH_F = f
> +endif
> +ifeq ($(CONFIG_RISCV_ISA_D),y)
> +       ARCH_D = d
> +ifeq ($(CONFIG_ARCH_RV32I),y)
> +       ABI_D = d
> +endif
> +endif
>  ifeq ($(CONFIG_RISCV_ISA_C),y)
>         ARCH_C = c
>  endif
> @@ -24,7 +33,9 @@ ifeq ($(CONFIG_CMODEL_MEDANY),y)
>         CMODEL = medany
>  endif
>
> -RISCV_MARCH = $(ARCH_BASE)$(ARCH_A)$(ARCH_C)
> +
> +RISCV_MARCH = $(ARCH_BASE)$(ARCH_A)$(ARCH_F)$(ARCH_D)$(ARCH_C)
> +ABI = $(ABI_BASE)$(ABI_D)
>
>  # Newer binutils versions default to ISA spec version 20191213 which moves some  # instructions from the I extension to the Zicsr and Zifencei extensions.
> --