Re: [PATCH 3/9] powerpc/mm/book3s-64: Use physical addresses in upper page table tree levels

Paul Mackerras [off-list ref] writes:

From: Paul Mackerras <redacted>

This changes the Linux page tables to store physical addresses
rather than kernel virtual addresses in the upper levels of the
tree (pgd, pud and pmd) for 64-bit Book 3S machines.

This frees up some high order bits, and will be needed with
PowerISA v3.0 machines which read the page table tree in hardware
in radix mode.

Radix mark the top two bits at upper level page table tree.

ie,


static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
{
	pud_set(pud, __pgtable_ptr_val(pmd));
}

static inline void rpud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
{
	*pud = __pud(__pa(pmd) | RPUD_VAL_BITS);
}


I guess we will do the same with hash to keep them same ?

-aneesh