[U-Boot] [PATCH] riscv: add Kconfig entries for the F and D ISA extensions support

[tesheng at andestech.com]

Hi Bin,

> -----Original Message-----
> From: Bin Meng [mailto:bmeng.cn at gmail.com]
> Sent: Tuesday, May 21, 2019 3:56 PM
> To: Eric Te-Sheng Lin(林德晟)
> Cc: U-Boot Mailing List; Lukas Auer; Anup Patel; Rick Jian-Zhi Chen(陳建志);
> Greentime Ying-Han Hu(胡英漢); dslin1010 at gmail.com
> Subject: Re: [PATCH] riscv: add Kconfig entries for the F and D ISA extensions
> support
>
> Hi Eric,
>
> On Tue, May 21, 2019 at 3:18 PM Eric Lin <tesheng at andestech.com> wrote:
> >
> > This patch add Kconfig entries for the F (Single-Precision)
>
> adds
>

OK I'll correct it as adds

> > and D (Double-Precision) floating point instruction-set extensions.
> >
>
> Could you please provide reason that why U-Boot has to be compiled using F/D
> extension?
>

Cause on AE350 platform, we have two different kinds of toolchain v5d (support I/M/A/C/F/D ISA) and
v5 (support I/M/A/C ISA). If we use the v5d toolchain to build U-Boot it will build fail, so we would like to add F/D extension on U-Boot.

> > Signed-off-by: Eric Lin <tesheng at andestech.com>
> > ---
> >  arch/riscv/Kconfig  |  8 ++++++++
> >  arch/riscv/Makefile | 12 ++++++++----
> >  2 files changed, 16 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index
> > 362f3cdc65..a8031fa230 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -91,6 +91,14 @@ config RISCV_ISA_C
> >           when building U-Boot, which results in compressed instructions
> in the
> >           U-Boot binary.
> >
> > +config RISCV_ISA_F
> > +       bool "Emit Floating-point instructions"
> > +       default n
>
> this can be dropped as default is n

OK, I'll drop it

> > +       help
> > +         Adds "F" to the ISA subsets that the toolchain is allowed to emit
> > +         when building U-Boot, which results in Single and
> > + Double-precision instructions
>
> This does not match what the config name says. The config name is for F and it
> cannot indicate both F and D here.
>

OK, I'll correct it as follows to cover F and D:
config RISCV_ISA_FD
    bool "Emit Floating-point instructions"
    help
      Adds "F" and "D" to the ISA subsets that the toolchain is allowed to emit
      when building U-Boot, which results in Single and Double-precision instructions
      in the U-Boot binary.


> > +         in the U-Boot binary.
> > +
> >  config RISCV_ISA_A
> >         def_bool y
> >
> > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index
> > 0b80eb8d86..87ec0ea4b5 100644
> > --- a/arch/riscv/Makefile
> > +++ b/arch/riscv/Makefile
> > @@ -5,15 +5,19 @@
> >
> >  ifeq ($(CONFIG_ARCH_RV64I),y)
> >         ARCH_BASE = rv64im
> > -       ABI = lp64
> > +       ABI := lp64
> >  endif
> >  ifeq ($(CONFIG_ARCH_RV32I),y)
> >         ARCH_BASE = rv32im
> > -       ABI = ilp32
> > +       ABI := ilp32
> >  endif
> >  ifeq ($(CONFIG_RISCV_ISA_A),y)
> >         ARCH_A = a
> >  endif
> > +ifeq ($(CONFIG_RISCV_ISA_F),y)
> > +       ARCH_F = fd

ifeq ($(CONFIG_RISCV_ISA_FD),y)
                  ARCH_FD = fd

> > +       ABI := $(ABI)d
> > +endif
> >  ifeq ($(CONFIG_RISCV_ISA_C),y)
> >         ARCH_C = c
> >  endif
> > @@ -24,8 +28,8 @@ ifeq ($(CONFIG_CMODEL_MEDANY),y)
> >         CMODEL = medany
> >  endif
> >
> > -ARCH_FLAGS = -march=$(ARCH_BASE)$(ARCH_A)$(ARCH_C) -mabi=$(ABI) \
> > -            -mcmodel=$(CMODEL)
> > +ARCH_FLAGS = -march=$(ARCH_BASE)$(ARCH_A)$(ARCH_F)$(ARCH_C)

ARCH_FLAGS = -march=$(ARCH_BASE)$(ARCH_A)$(ARCH_FD)$(ARCH_C)

> -mabi=$(ABI) \
> > +                                -mcmodel=$(CMODEL)
> >
> >  PLATFORM_CPPFLAGS      += $(ARCH_FLAGS)
> >  CFLAGS_EFI             += $(ARCH_FLAGS)
> > --
>
> Regards,
> Bin

Thanks for your review.

Regards,
Eric
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