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Date: Mon, 8 Dec 2008 19:14:26 -0800 (PST)
From: Trent Piepho <tpiepho@freescale.com>
To: Kumar Gala <galak@kernel.crashing.org>
Subject: Re: [PATCH] powerpc/85xx: Add support for SMP initialization
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Cc: linuxppc-dev@ozlabs.org, Fleming Andy <afleming@freescale.com>
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On Tue, 2 Dec 2008, Kumar Gala wrote:
> Added 85xx specifc smp_ops structure.  We use ePAPR style boot release
> and the MPIC for IPIs at this point.
>
> Additionally added routines for secondary cpu entry and initializtion.
>
> @@ -740,6 +750,9 @@ finish_tlb_load:
> #else
> 	rlwimi	r12, r11, 26, 27, 31	/* extract WIMGE from pte */
> #endif
> +#ifdef CONFIG_SMP
> +	ori	r12, r12, MAS2_M
> +#endif
> 	mtspr	SPRN_MAS2, r12

Wouldn't it be more efficient to set _PAGE_COHERENT when the pte is created
vs setting MAS2_M each time it's loaded?

Is it correct to set MAS2_M for all pages, even uncached ones?

The code for ioremap() has this:

         /* Non-cacheable page cannot be coherent */
         if (flags & _PAGE_NO_CACHE)
                 flags &= ~_PAGE_COHERENT;

It seems odd that ioremap would explictly unset _PAGE_COHERENT when the
code that sets the tlb will just force it back on.