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SubjectRe: [PATCH v2] powerpc 8xx: Fixing issue with CONFIG_PIN_TLB
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On Thu, 2013-09-12 at 20:25 +0200, Christophe Leroy wrote:
> This is a reorganisation of the setup of the TLB at kernel startup, in order
> to handle the CONFIG_PIN_TLB case in accordance with chapter 8.10.3 of MPC866
> and MPC885 reference manuals.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>
> diff -ur linux-3.11.org/arch/powerpc/kernel/head_8xx.S linux-3.11/arch/powerpc/kernel/head_8xx.S
> --- linux-3.11.org/arch/powerpc/kernel/head_8xx.S 2013-09-02 22:46:10.000000000 +0200
> +++ linux-3.11/arch/powerpc/kernel/head_8xx.S 2013-09-09 11:28:54.000000000 +0200
> @@ -785,27 +785,24 @@
> * these mappings is mapped by page tables.
> */
> initial_mmu:
> - tlbia /* Invalidate all TLB entries */
> -/* Always pin the first 8 MB ITLB to prevent ITLB
> - misses while mucking around with SRR0/SRR1 in asm
> -*/
> - lis r8, MI_RSV4I@h
> - ori r8, r8, 0x1c00
> -
> + lis r8, MI_RESETVAL@h
> mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */
>
> -#ifdef CONFIG_PIN_TLB
> - lis r10, (MD_RSV4I | MD_RESETVAL)@h
> - ori r10, r10, 0x1c00
> - mr r8, r10
> -#else
> lis r10, MD_RESETVAL@h
> -#endif
> #ifndef CONFIG_8xx_COPYBACK
> oris r10, r10, MD_WTDEF@h
> #endif
> mtspr SPRN_MD_CTR, r10 /* Set data TLB control */
>
> + tlbia /* Invalidate all TLB entries */

Is this change to make sure we invalidate everything even if the
bootloader set RSV4I?

> + ori r8, r8, 0x1c00
> + mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */
> +#ifdef CONFIG_PIN_TLB
> + ori r10, r10, 0x1c00
> + mtspr SPRN_MD_CTR, r10 /* Set data TLB control */
> +#endif

Still 0x1c00?

> /* Now map the lower 8 Meg into the TLBs. For this quick hack,
> * we can load the instruction and data TLB registers with the
> * same values.
> @@ -825,6 +822,12 @@
> mtspr SPRN_MI_AP, r8
> mtspr SPRN_MD_AP, r8
>
> + /* Always pin the first 8 MB ITLB to prevent ITLB
> + * misses while mucking around with SRR0/SRR1 in asm
> + */
> + lis r8, (MI_RSV4I | MI_RESETVAL)@h
> + mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */

Entry 0 is not pinnable.

-Scott





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