1. 根目录:
2. include
3. asm-generic
4. page.h

#ifndef __ASM_GENERIC_PAGE_H
#define __ASM_GENERIC_PAGE_H
/*
 * Generic page.h implementation, for NOMMU architectures.
 * This provides the dummy definitions for the memory management.
 */

#ifdef CONFIG_MMU
#error need to prove a real asm/page.h
#endif


/* PAGE_SHIFT determines the page size */

#define PAGE_SHIFT	12
#ifdef __ASSEMBLY__
#define PAGE_SIZE	(1 << PAGE_SHIFT)
#else
#define PAGE_SIZE	(1UL << PAGE_SHIFT)
#endif
#define PAGE_MASK	(~(PAGE_SIZE-1))

#include <asm/setup.h>

#ifndef __ASSEMBLY__

#define get_user_page(vaddr)		__get_free_page(GFP_KERNEL)
#define free_user_page(page, addr)	free_page(addr)

#define clear_page(page)	memset((page), 0, PAGE_SIZE)
#define copy_page(to,from)	memcpy((to), (from), PAGE_SIZE)

#define clear_user_page(page, vaddr, pg)	clear_page(page)
#define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)

/*
 * These are used to make use of C type-checking..
 */
typedef struct {
	unsigned long pte;
} pte_t;
typedef struct {
	unsigned long pmd[16];
} pmd_t;
typedef struct {
	unsigned long pgd;
} pgd_t;
typedef struct {
	unsigned long pgprot;
} pgprot_t;
typedef struct page *pgtable_t;

#define pte_val(x)	((x).pte)
#define pmd_val(x)	((&x)->pmd[0])
#define pgd_val(x)	((x).pgd)
#define pgprot_val(x)	((x).pgprot)

#define __pte(x)	((pte_t) { (x) } )
#define __pmd(x)	((pmd_t) { (x) } )
#define __pgd(x)	((pgd_t) { (x) } )
#define __pgprot(x)	((pgprot_t) { (x) } )

extern unsigned long memory_start;
extern unsigned long memory_end;

#endif /* !__ASSEMBLY__ */

#ifdef CONFIG_KERNEL_RAM_BASE_ADDRESS
#define PAGE_OFFSET		(CONFIG_KERNEL_RAM_BASE_ADDRESS)
#else
#define PAGE_OFFSET		(0)
#endif

#ifndef __ASSEMBLY__

#define __va(x) ((void *)((unsigned long)(x) + PAGE_OFFSET))
#define __pa(x) ((unsigned long) (x) - PAGE_OFFSET)

#define virt_to_pfn(kaddr)	(__pa(kaddr) >> PAGE_SHIFT)
#define pfn_to_virt(pfn)	__va((pfn) << PAGE_SHIFT)

#define virt_to_page(addr)	(mem_map + (((unsigned long)(addr)-PAGE_OFFSET) >> PAGE_SHIFT))
#define page_to_virt(page)	((((page) - mem_map) << PAGE_SHIFT) + PAGE_OFFSET)

#ifndef page_to_phys
#define page_to_phys(page)      ((dma_addr_t)page_to_pfn(page) << PAGE_SHIFT)
#endif

#define pfn_valid(pfn)		((pfn) < max_mapnr)

#define	virt_addr_valid(kaddr)	(((void *)(kaddr) >= (void *)PAGE_OFFSET) && \
				((void *)(kaddr) < (void *)memory_end))

#endif /* __ASSEMBLY__ */

#include <asm-generic/memory_model.h>
#include <asm-generic/getorder.h>

#endif /* __ASM_GENERIC_PAGE_H */