Re: 440GX tlb problem?

On Fri, Jun 11, 2004 at 02:40:05PM -0400, Travis Sawyer wrote:

Greetings:

I'm attempting to bring up a new board (our custom hw) and am blowing an
Instruction TLB error in head_440.S where the original TLB for SDRAM

head_440.S indicates you are using a really old kernel.

(u-boot and initial kernel space) is invalidated after we've switched to
0xc000_0000.

What do you mean?  Your u-boot port has invalidated caches? are you
running out of 0xc0000000 before you get here?  Which TLB entry are
you executing from?

the instructions:
3:/*	iccci   r0,r0    rcblach 12/19/02 clear all caches again on 1/17/03
I took out these changes
	dccci   r0,r0    again clear all caches */
	cmpwi	r23,62
	beq	4f
	li	r6,0
	tlbwe   r6,r23,PPC440_TLB_PAGEID
	sync

By the comments, it's an IBM supplied kernel.  This isn't anything
in the kernel.org or linuxppc kernel trees.

The exception hits when the sync is executed.

Maybe you are executing from TLB entry 62, that's one of the
undocumented limitations...you can entry head_44x.S running in
entry 62.

Any ideas?

Can you try a current kernel tree? kernel.org 2.4 or 2.6.  The IBM
kernel trees are old and buggy (_buggier_).

-Matt

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