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linux内核学习(4)建立正式内核的页式内存映射, 以x86 32位模式为例

void __init setup_arch(char **cmdline_p){	max_low_pfn_mapped = init_memory_mapping(0, max_low_pfn<
   
    unsigned long __init_refok init_memory_mapping(unsigned long start, unsigned long end)	{		for (i = 0; i < nr_range; i++)			ret = kernel_physical_mapping_init(mr[i].start, mr[i].end, mr[i].page_size_mask);			=>unsigned long __init kernel_physical_mapping_init(unsigned long start,					unsigned long end,					unsigned long page_size_mask)			{				和页表项				start_pfn = start >> PAGE_SHIFT;				end_pfn = end >> PAGE_SHIFT;				pgd_t *pgd_base = swapper_pg_dir;				pages_2m = pages_4k = 0;				pfn = start_pfn;				pgd_idx = pgd_index((pfn<
    
     pte_t * __init one_page_table_init(pmd_t *pmd)						{							if (!(pmd_val(*pmd) & _PAGE_PRESENT)) {	// 生成页表								pte_t *page_table = NULL;								if (after_bootmem) {						#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KMEMCHECK)									page_table = (pte_t *) alloc_bootmem_pages(PAGE_SIZE);						#endif									if (!page_table)										page_table =										(pte_t *)alloc_bootmem_pages(PAGE_SIZE);								} else									page_table = (pte_t *)alloc_low_page();								paravirt_alloc_pte(&init_mm, __pa(page_table) >> PAGE_SHIFT);								set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE)); // 将页表物理地址写在页目录项								BUG_ON(page_table != pte_offset_kernel(pmd, 0));							}							return pte_offset_kernel(pmd, 0);						}						pte_ofs = pte_index((pfn<
     
      << PAGE_SHIFT) + PAGE_SIZE;							} else								set_pte(pte, pfn_pte(pfn, prot));						}					}				}							}		early_ioremap_page_table_range_init();		load_cr3(swapper_pg_dir);	}}
     
    
   

Linux内核源码学习 （1）- 从实模式到保护模式

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