Re: [PATCH 1/2] tune-riscv: Add support for hard and soft float

[Adrian Bunk <bunk@stusta.de>]

On Thu, Nov 07, 2019 at 04:39:22PM -0800, Alistair Francis wrote:
> On Wed, Nov 6, 2019 at 11:33 PM Nathan Rossi <nathan@nathanrossi.com> wrote:
> >
> > On Thu, 7 Nov 2019 at 09:34, Adrian Bunk <bunk@stusta.de> wrote:
> > >
> > > On Wed, Nov 06, 2019 at 10:18:18AM -0800, Alistair Francis wrote:
> > > >...
> > > > +TUNE_CCARGS_riscv64 .= "${@bb.utils.contains('TUNE_FEATURES', 'riscv64-f', ' -mabi=lp64d', ' -mabi=lp64', d)}"
> > > > +TUNE_CCARGS_riscv32 .= "${@bb.utils.contains('TUNE_FEATURES', 'riscv32-f', ' -mabi=ilp32f', ' -mabi=ilp32', d)}"
> > > >...
> > >
> > > That looks wrong, what would you put in TUNE_FEATURES
> > > for -mabi=lp64f when -mabi=lp64d is called riscv64-f?
> > >
> > > Also note that this is only the floating point calling convention,
> > > whether the compiler emits floating point instructions is defined
> > > by -march.
> > >
> > > It would be good if this would start with a plan how to handle
> > > all possible combination of RISC-V ISA extensions, ideally better
> > > than the arm mess.
> >
> > I am keen to see this as well, since I am currently directly
> > hardcoding -march/-mabi in the machine conf.
> >
> > It would be nice to see the ISA tunes available in oe-core, even if
> > that is just the tune features and not predefined tunes (e.g. like
> > microblaze).
> 
> I think this idea as well. Some generic way of generating tunes from
> ISA stings would be great!
> 
> Does anyone have any ideas on the best way to do this?

Especially when looking at the arm64 situation I am wondering whether 
the best option might be to throw away the tunes mess and let the user 
write the compiler options directly.

If OE needs information about a specific feature, it would be easier to 
ask the compiler[1] than duplicating all the target knowledge.

> Alistair

cu
Adrian

[1] $CC -dM -E - < /dev/null

-- 

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       "Only a promise," Lao Er said.
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