[OE-core] [PATCH] Revert "cross-canadian: Handle powerpc linux verses linux-gnuspe"

[alexandru.sardan at freescale.com]

Hi,

See my comment inline.

Alex

> -----Original Message-----
> From: openembedded-core-bounces at lists.openembedded.org
> [mailto:openembedded-core-bounces at lists.openembedded.org] On Behalf Of
> Richard Purdie
> Sent: Tuesday, January 21, 2014 7:43 PM
> To: Sardan Alexandru Cezar-B41700
> Cc: Udma Catalin-Dan-B32721; openembedded-core at lists.openembedded.org
> Subject: Re: [OE-core] [PATCH] Revert "cross-canadian: Handle powerpc
> linux verses linux-gnuspe"
> 
> On Tue, 2014-01-21 at 17:39 +0000, alexandru.sardan at freescale.com wrote:
> > Yes, the gcc configured for SPE (--target=powerpc-fsl_networking-linux-
> gnuspe)
> > can generate both SPE and non-SPE code provided that software
> > floating point is used.
> >
> > There are a couple of parameters (-mabi=no-spe -mno-spe) that will turn
> > off SPE vector instructions generation. If the code contains floating
> > point arithmethic -msoft-float needs to be used as well. This means
> that
> > the GCC multilib setup has to be configured to include soft float and
> > build coresponding version of libgcc and target fragments.
> > But why would we want to generate code without SPE for e500v1/v2?
> > Soft-float comes with a major performance penalty.
> >
> > Maybe I didn't understand correctly what kind of toolchain you want to
> > be built in the end. Do you want to have a single GCC that builds all
> > powerpc targets (e500v2, e5500, e6500 etc) and a separate sysroot for
> each
> > target?
> 
> Yes, this is exactly what is wanted. This is how the SDK is intended to
> operate. The alternative and what we had before was a separate compiler
> for each target which is rather wasteful.
> 
> > This may be problematic since, for example, the compiler that can
> generate
> > SPE (for e500v2) can't generate altivec instructions (for e6500).
> 
> Is there no way to configure gcc so it can generate for the different
> targets assuming you pass in the right runtime target options?

[Alex Sardan] No. The more generic target powerpc-none-linux will not
generate SPE code and the powerpc-none-linux-gnuspe target that generates
SPE will not be able to generate Altivec.
Maybe an exception can be added for e500v1/v2 targets so that a separate
compiler can be generated for them? All the other targets will work fine
with powerpc-none-linux using different runtime command line options.

> 
> Cheers,
> 
> Richard
> 
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