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Re: [PATCH] samples: add arm-cortexa9_neon-linux-gnueabihf


Hi Yann, all,

On Saturday, February 16, 2013 12:31:12 AM, Yann E. MORIN wrote:
> BenoÃt, All,
> 
> On Tuesday 05 February 2013 BenoÃt ThÃbaudeau wrote:
> > # HG changeset patch
> > # User "BenoÃt ThÃbaudeau" <benoit.thebaudeau@advansee.com>
> > # Date 1360063792 -3600
> > # Node ID bdf1fde968aee8d0cd953aa1bc1068537fab1dc3
> > # Parent  20f2459b97bf5eb89e2f125e0aede9541e7fc049
> > samples: add arm-cortexa9_neon-linux-gnueabihf
> [--SNIP--]
> > +CT_ARCH_FPU="neon"
> 
> Is that really 'neon' ?

Yes, for Cortex-A8/9 (VFPv3).

> I thought its gcc name was something like
> 'neon-vfpv4' (or v3?)...

'neon-vfpv4' exists, but it is for CortexA5/15 (VFPv4).

> [--SNIP--]
> > +CT_CC_CORE_EXTRA_CONFIG_ARRAY="\"--with-specs=%{save-temps: -fverbose-asm}
> > %{funwind-tables|fno-unwind-tables|mabi=*|ffreestanding|nostdlib:;:
> > -funwind-tables}\" --enable-poison-system-directories"
> 
> Can you explain what this specific specs are supposed to achieve (sorry,
> I am not fluent in gcc's specs) and why they are needed?

I had taken that from the Sourcery build script at the time of the fork with
Linaro in order to use exactly the same build options as them, and I have kept
this since then.

It means:
 - Pass '-fverbose-asm' to the subprocess if '-save-temps' was given to GCC. If
   the user asks to keep the temporary build files, it is in order to read them,
   so making them verbose helps for debug purposes.
 - Pass '-funwind-tables' to the subprocess if neither '-funwind-tables' nor
   '-fno-unwind-tables' nor '-mabi=*' nor '-ffreestanding' nor '-nostdlib' was
   given to GCC. This seems to also be more for debug purposes than something
   really needed.

Best regards,
BenoÃt

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