How to the the physical addresses under linux (au1500)

I am trying to program the DMA (with the ac97) in assembler using a linux kernel module for mips teaching purposes.
The problem is that I need to get the physical address of the pointer to the buffer to transfer to the AC97.
Looking at the kernel source code, I found that I can get the physical address subtracting 0x8000000, but It doesnt seem to work.

Any idea?

Thanks,

Sergio

I think you want to choose a more simple teaching example :-)

Not always. On systems like this one that are not cache coherent, we play games with mapped addresses to get uncached spaces or you need to apply various macros/functions to keep the space coherent.

Use a more simple example. Maybe just update one of the LED displays on the board.

	-- Dan