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Subject: Re: [Patch ] Kexec/Kdump support - POWER6
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: sachinp@in.ibm.com
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Date: Tue, 29 May 2007 07:31:34 +1000
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Cc: linuxppc-dev@ozlabs.org, Paul Mackerras <paulus@samba.org>,
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On Mon, 2007-05-28 at 17:10 +0530, Sachin P. Sant wrote:
> 
> +#define HPTE_V_1TB_SEG         ASM_CONST(0x4000000000000000)
> +#define HPTE_V_VRMA_MASK       ASM_CONST(0x4001ffffff)

Move those to mmu-hash64.h along with the other ones. Also, keep the
mask aligned to the top bits

>  static void pSeries_lpar_hptab_clear(void)
>  {
>         unsigned long size_bytes = 1UL << ppc64_pft_size;
>         unsigned long hpte_count = size_bytes >> 4;
> -       unsigned long dummy1, dummy2;
> +       unsigned long dummy1, dummy2, dword0;
> +       long lpar_rc;
>         int i;
>  
>         /* TODO: Use bulk call */
> -       for (i = 0; i < hpte_count; i++)
> -               plpar_pte_remove_raw(0, i, 0, &dummy1, &dummy2);
> +       for (i = 0; i < hpte_count; i++) {
> +               /* dont remove HPTEs with VRMA mappings */
> +               lpar_rc = plpar_pte_remove_raw(H_ANDCOND, i, HPTE_V_1TB_SEG,
> +                                               &dummy1, &dummy2);
> +               if (lpar_rc == H_NOT_FOUND) {
> +                       lpar_rc = plpar_pte_read_raw(0, i, &dword0, &dummy1);
> +                       if (!lpar_rc && (((dword0 >> 24) & HPTE_V_VRMA_MASK) 
> +                               != HPTE_V_VRMA_MASK))

No need to shift >> 24, just have the mask left justified in the first
place. No need to have a "magic" shift value in there.

> +                               /* Can be hpte for 1TB Seg. So remove it */
> +                               plpar_pte_remove_raw(0, i, 0, &dummy1, &dummy2);
> +               }
> +       }
>  }

Appart from that, looks good. Does it actually work ? :-)

Cheers,
Ben.