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Subject: Re: [RFC][PATCH] powerpc/CoreNet64: compile with
 CONFIG_E{5,6}500_CPU well
From: Scott Wood <scottwood@freescale.com>
To: Tiejun Chen <tiejun.chen@windriver.com>
Date: Wed, 20 Nov 2013 10:41:11 -0600
In-Reply-To: <1384936551-8494-1-git-send-email-tiejun.chen@windriver.com>
References: <1384936551-8494-1-git-send-email-tiejun.chen@windriver.com>
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On Wed, 2013-11-20 at 16:35 +0800, Tiejun Chen wrote:
> CONFIG_ALTIVEC is always enabled for CoreNet64.

In the defconfig perhaps, but this isn't a generally true statement.

> And if we select CONFIG_E{5,6}500_CPU this may introduce -mcpu=e500mc64
> into $CFLAGS. But Altivec and Spe options not allowed with
> e500mc64, so :

Sigh.

>   CC      arch/powerpc/lib/xor_vmx.o
> arch/powerpc/lib/xor_vmx.c:1:0: error: AltiVec not supported in this target
> make[1]: *** [arch/powerpc/lib/xor_vmx.o] Error 1
> make: *** [arch/powerpc/lib] Error 2
> 
> Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
> ---
>  arch/powerpc/lib/Makefile |    3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
> index 95a20e1..641a77d 100644
> --- a/arch/powerpc/lib/Makefile
> +++ b/arch/powerpc/lib/Makefile
> @@ -40,5 +40,8 @@ obj-y			+= code-patching.o
>  obj-y			+= feature-fixups.o
>  obj-$(CONFIG_FTR_FIXUP_SELFTEST) += feature-fixups-test.o
>  
> +# Altivec and Spe options not allowed with e500mc64 in GCC.
> +ifeq ($(call cc-option-yn,-mcpu=e500mc64),n)
>  obj-$(CONFIG_ALTIVEC)	+= xor_vmx.o
>  CFLAGS_xor_vmx.o += -maltivec -mabi=altivec
> +endif

This does not seem like the right fix.  What if GCC supports both
-mcpu=e500mc64 and -mcpu=e6500, and we're using the latter?  Or for that
matter, if we're using -mcpu=whatever-ibm-chip-has-this?

Plus, wouldn't you need to do something to prevent code in that file
from being called?

-Scott