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Subject: Re: [PATCH] Add support for FP emulation for the e300c2 core
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Kim Phillips <kim.phillips@freescale.com>
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Date: Thu, 23 Nov 2006 08:34:34 +1100
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> +BEGIN_FTR_SECTION
> +/*
> + * certain freescale cores treat 'normal' floating point instructions
> + * as FP Unavail exception.  Redirect to normal illegal/emulation handling.
> + */
> +	b 	ProgramCheck
> +END_FTR_SECTION_IFSET(CPU_FTR_FP_TAKES_FPUNAVAIL)
>  	EXCEPTION_PROLOG
>  	bne	load_up_fpu		/* if from user, just load it up */
>  	addi	r3,r1,STACK_FRAME_OVERHEAD

Do you absolutely need that ? Is there any way those cores will actually
send a "normal" FPUnavail exception ? If not, don't bother. There aren't
that many CPU feature bits left so let's not use one for something that
never happens.

Ben.