S/F core

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originally posted by smalllight@Oct 19 2006, 02:00 PM

tank you for you replies.

i have readed the ioremap.c

the __ioremap's code as follow:

__ioremap() in file arch/nios2nommu/mm/ioremap.c

/*

* map some physical address range into the kernel address space.

*/

void *__ioremap(unsigned long physaddr, unsigned long size, int cacheflag)

{

return (void *)(physaddr);

}

hippo can you tell me why you change the code to "return (void *)(physaddr|0x80000000); "?

i will regard your comment ,thank you

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Smcnutt had noted ioremap() in this thread,

http://forum.niosforum.com/forum/index.php...=735&hl=ioremap (http://forum.niosforum.com/forum/index.php?showtopic=735&hl=ioremap)

Next, look at the cfi flash map driver, linux-2.6.x/drivers/mtd/maps/altera.c

nt __init init_alteramap(void)

{

static const char *rom_probe_types[] = {"cfi_probe", "jedec_probe", 0 };

const char **type;

ndk_amd_map.virt = (unsigned long *)ioremap_nocache(WINDOW_ADDR, WINDOW_SIZE);

Look at the ioremap() and ioremap_nocache() in linux-2.6.x/include/asm-nios2nommu/io.h

they all want the return be uncached address.

Though the mtd map use the uncached functions (from io.h) to access memory, linux-2.6.x/include/linux/mtd/map.h

Actually, the original code did not do anything about uncache.

I could agree with that, if all the access are consistent.

ie, always use the uncached functions (from io.h) to access memory,

and never mix access with the cached virt address .