pagetable_init()

pagetable_init()根据物理内存初始化页目录项及页表项

static   void  __init pagetable_init ( void )
... {
    unsigned long vaddr;
    pgd_t *pgd_base = swapper_pg_dir;

#ifdef CONFIG_X86_PAE
    int i;
     //初始化整个页目录项(1024项)
    for (i = 0; i < PTRS_PER_PGD; i++)
        set_pgd(pgd_base + i, __pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
#endif

    if (cpu_has_pse) ...{
        set_in_cr4(X86_CR4_PSE);
    }
    if (cpu_has_pge) ...{
        set_in_cr4(X86_CR4_PGE);
        __PAGE_KERNEL |= _PAGE_GLOBAL;
        __PAGE_KERNEL_EXEC |= _PAGE_GLOBAL;
    }
    kernel_physical_mapping_init(pgd_base);
    remap_numa_kva();
    vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
    page_table_range_init(vaddr, 0, pgd_base);

    permanent_kmaps_init(pgd_base);

#ifdef CONFIG_X86_PAE
    pgd_base[0] = pgd_base[USER_PTRS_PER_PGD];
#endif
}