On Wed, 2009-11-25 at 16:00 +0000, Ralf Baechle wrote: > On Wed, Nov 25, 2009 at 11:31:14PM +0800, Figo.zhang wrote: > > > how to do map extra RAM to any ouside I/O space? > > it is just motify: > > > > 1. arch/mips/kernel/setup.c: bootm_init()function, motity the define > > "HIGHMEM_START", for me: > > #define HIGHMEM_START 0x2000,0000 //512MB > > Leave HIGHMEM_START unchanged; it should always be 512MB no matter what > the actual memory addresses of a particular platform are. The kernel > needs to treat anything above 512MB differently because it's not > permanently mapped and HIGHMEM_START stands for this limit. > HIGHMEM canot directly invoke __get_free_pages() to allocate pages, so it would slow performance ? Is it anyother solution in current linux-mips kernel? for example, directly map extra RAM to 0x40000000~0x80000000, the user space decreased, only 0x0~0x40000000. Best, Figo.zhang > Ralf
