lock_kernel()只虚晃一枪就过去了．

紧接着来的是page_address_init

include/linux/mm.h

 

#if defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL)
#define HASHED_PAGE_VIRTUAL
#endif

宏CONFIG_HIGHMEM 在系统中是未定义的

宏WANT_PAGE_VIRTUAL 在系统中也是未定义的

 

#if defined(WANT_PAGE_VIRTUAL)
#define page_address(page) ((page)->virtual)
#define set_page_address(page, address)            /
    do {                        /
        (page)->virtual = (address);        /
    } while(0)
#define page_address_init()  do { } while(0)
#endif

这个不是

 

#if defined(HASHED_PAGE_VIRTUAL)
void *page_address(struct page *page);
void set_page_address(struct page *page, void *virtual);
void page_address_init(void);
#endif

这个也不是

 

#if !defined(HASHED_PAGE_VIRTUAL) && !defined(WANT_PAGE_VIRTUAL)
#define page_address(page) lowmem_page_address(page)
#define set_page_address(page, address)  do { } while(0)
#define page_address_init()  do { } while(0)
#endif

就这个了，也是空操作！！！

 

ps:某些平台就定义了CONFIG_HIGHMEM 例如： ppc/stx_gp3，说明这些是平台相关的.