Relocating interrupt vectors in ppc440?

Shawn Jin shawnxjin at
Fri Jan 28 12:55:01 EST 2005

> > I guess the value set to PPC_MEMSTART should be the offset to the
> > physical starting address of 2GB SDRAM not the absolute physical
> > address, right?
> It would be 0x00000000 for the first processor and 0x40000000 for the
> second processor. Note that head_44x.S is a major place where a lot
> of "system memory is at zero" assumptions take place that need to
> be addressed for the second processor.

The theory behind changing PPC_MEMSTART is to change MMU configuration
and to let it translate 0xC0000000 to 0x40000000 for the 2nd
processor. Right?

One place I found the assumption is when loading the kernel physical address.
	/* Kernel is at the base of RAM */
	li r4, 0			/* Load the kernel physical address */

I'll find out more places as you indicated.

Best regards,

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