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Subject: Re: [PATCH 1/5] powerpc: Add platform support for AmigaOne
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Scott Wood <scottwood@freescale.com>
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Date: Mon, 12 Jan 2009 16:08:07 +1100
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> > +	/* Flush and disable I/D cache. */
> > +	__asm__ __volatile__ ("mfspr	3, 1008"	::: "r3");
> > +	__asm__ __volatile__ ("ori	5, 5, 0xcc00"	::: "r5");
> > +	__asm__ __volatile__ ("ori	4, 3, 0xc00"	::: "r4");
> > +	__asm__ __volatile__ ("andc	5, 3, 5"	::: "r5");
> 
> Don't do this; instead, have one multi-line asm statement (or better yet,
> just use mfspr()/mtspr()/sync()/isync()).
> 
> GCC is perfectly free to trash your registers in between statements.

Also there's already some code around to properly flush & disable the
caches on those processors.

Ben.