[PATCH] Makefile: Add option to use toolchain default ABI and ISA string

[Anup Patel]

> -----Original Message-----
> From: Jessica Clarke <jrtc27 at jrtc27.com>
> Sent: 30 October 2020 03:28
> To: Alistair Francis <Alistair.Francis at wdc.com>
> Cc: Atish Patra <Atish.Patra at wdc.com>; Anup Patel
> <Anup.Patel at wdc.com>; anup at brainfault.org; opensbi at lists.infradead.org
> Subject: Re: [PATCH] Makefile: Add option to use toolchain default ABI and
> ISA string
> 
> On 29 Oct 2020, at 17:08, Alistair Francis <Alistair.Francis at wdc.com> wrote:
> >
> > On Thu, 2020-10-29 at 14:28 +0530, Anup Patel wrote:
> >> When PLATFORM_RISCV_ABI and PLATFORM_RISCV_ISA are not
> specified, we
> >> force "-mabi=lp64 -march=rv64gc" for RV64 and force "-mabi=ilp32
> >> -march=rv32gc" for RV32. This can prevent users from using the
> >> toolchain default "-mabi" and "-march" options.
> >>
> >> To allow using toolchain defaults, we add compile-time option
> >> PLATFORM_RISCV_TOOLCHAIN_DEFAULT which when enabled forces the
> >> top-level makefile to use toolchain default ABI and ISA string.
> >>
> >> To enable the option, pass "PLATFORM_RISCV_TOOLCHAIN_DEFAULT=1"
> >> to top-level make.
> >>
> >> Reported-by: Alistair Francis <alistair.francis at wdc.com>
> >> Signed-off-by: Anup Patel <anup.patel at wdc.com>
> >
> > Thanks!
> >
> > Reviewed-by: Alistair Francis <alistair.francis at wdc.com>
> 
> FYI, --with-arch/--with-abi are GCC-specific configure flags. Clang doesn't
> have such a notion, and even if it did it's using CMake so those would be
> differently-named. Though I don't understand why we need to probe to see
> what they are; if you want the default, just don't specify -march/-mabi?
> Seems a bit unnecessary to go and ask what the default is only to then
> explicitly give it to the tool you just asked.

Okay, sounds good to me. Let's just skip specifying "-mabi/-march" when
"PLATFORM_RISCV_TOOLCHAIN_DEFAULT=1"

Regards,
Anup