diff options
Diffstat (limited to 'arch/powerpc/include')
-rw-r--r-- | arch/powerpc/include/asm/book3s/64/pgtable.h | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h index 96566df..1f9e984 100644 --- a/arch/powerpc/include/asm/book3s/64/pgtable.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h @@ -39,6 +39,30 @@ #define _RPAGE_RPN0 0x01000 #define _RPAGE_RPN1 0x02000 +/* Max physical address bit as per radix table */ +#define _RPAGE_PA_MAX 57 + +/* + * Max physical address bit we will use for now. + * + * This is mostly a hardware limitation and for now Power9 has + * a 51 bit limit. + * + * This is different from the number of physical bit required to address + * the last byte of memory. That is defined by MAX_PHYSMEM_BITS. + * MAX_PHYSMEM_BITS is a linux limitation imposed by the maximum + * number of sections we can support (SECTIONS_SHIFT). + * + * This is different from Radix page table limitation above and + * should always be less than that. The limit is done such that + * we can overload the bits between _RPAGE_PA_MAX and _PAGE_PA_MAX + * for hash linux page table specific bits. + * + * In order to be compatible with future hardware generations we keep + * some offsets and limit this for now to 53 + */ +#define _PAGE_PA_MAX 53 + #define _PAGE_SOFT_DIRTY _RPAGE_SW3 /* software: software dirty tracking */ #define _PAGE_SPECIAL _RPAGE_SW2 /* software: special page */ @@ -51,10 +75,11 @@ */ #define _PAGE_NO_CACHE _PAGE_TOLERANT /* - * We support 57 bit real address in pte. Clear everything above 57, and - * every thing below PAGE_SHIFT; + * We support _RPAGE_PA_MAX bit real address in pte. On the linux side + * we are limited by _PAGE_PA_MAX. Clear everything above _PAGE_PA_MAX + * and every thing below PAGE_SHIFT; */ -#define PTE_RPN_MASK (((1UL << 57) - 1) & (PAGE_MASK)) +#define PTE_RPN_MASK (((1UL << _PAGE_PA_MAX) - 1) & (PAGE_MASK)) /* * set of bits not changed in pmd_modify. Even though we have hash specific bits * in here, on radix we expect them to be zero. |