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Subject: Re: I think I have 8xx working...
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Rex Feany <rfeany@mrv.com>
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Date: Thu, 15 Oct 2009 12:00:58 +1100
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On Wed, 2009-10-14 at 17:41 -0700, Rex Feany wrote:
> The biggest problem for me turned out to be the MMU context IDs being
> clamped to 32 when the 8xx only has 16. With this, things are a bit more
> stable :)

Ugh ? The clamp went upstream ? That sucks... let me fix that asap

Cheers,
Ben.

> diff --git a/arch/powerpc/mm/mmu_context_nohash.c b/arch/powerpc/mm/mmu_context_nohash.c
> index c2f93dc..15e00c5 100644
> --- a/arch/powerpc/mm/mmu_context_nohash.c
> +++ b/arch/powerpc/mm/mmu_context_nohash.c
> @@ -404,7 +404,8 @@ void __init mmu_context_init(void)
>  	}
>  
>  #ifdef DEBUG_CLAMP_LAST_CONTEXT
> -	last_context = DEBUG_CLAMP_LAST_CONTEXT;
> +	if (last_context > DEBUG_CLAMP_LAST_CONTEXT)
> +	    last_context = DEBUG_CLAMP_LAST_CONTEXT;
>  #endif
>  	/*
>  	 * Allocate the maps used by context management
> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
> index e7dae82..26fb6b9 100644
> --- a/arch/powerpc/mm/fault.c
> +++ b/arch/powerpc/mm/fault.c
> @@ -40,7 +40,7 @@
>  #include <asm/uaccess.h>
>  #include <asm/tlbflush.h>
>  #include <asm/siginfo.h>
> -
> +#include <mm/mmu_decl.h>
>  
>  #ifdef CONFIG_KPROBES
>  static inline int notify_page_fault(struct pt_regs *regs)
> @@ -246,6 +246,12 @@ good_area:
>  		goto bad_area;
>  #endif /* CONFIG_6xx */
>  #if defined(CONFIG_8xx)
> +	/* 8xx sometimes need to load a invalid/non-present TLBs.
> +	 * These must be invalidated separately as linux mm don't.
> +	 */
> +	if (error_code & 0x40000000) /* no translation? */
> +		_tlbil_va(address, 0, 0, 0);
> +
>          /* The MPC8xx seems to always set 0x80000000, which is
>           * "undefined".  Of those that can be set, this is the only
>           * one which seems bad.