cache_status looks at wrong bit for MPC8560

Hi, the [id]cache_status functions in the MPC85xx start.S code look at the wrong bit in the L1CSRn registers for the MPC8560. I have a patch for it, but I was wondering if the code is wrong for all 85xx processors, or just the 8560. Rather than me downloading all the 85xx user manuals and checking the register bits (as I am only interested in 8560) I thought I would post here instead. If anyone knows for certain the code is correct or otherwise for other 85xx processors, please let me know. Cheers!

								Murray...

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Murray Jensen, CSIRO Manufacturing & Infra. Tech. Phone: +61 3 9662 7763
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If they are wrong on 8560 they are wrong on 85xx since the same code is used for all 85xx.

However, looking at the code my guess is that [id]cache_status return 0 if the caches are off and any non-zero value if they are on. So from that point of view the code appears to be ok. When you say they are looking at the wrong bit, what exactly do you mean?

- kumar

This code:

	srwi    r3, r3, 31      /* >>31 => select bit 0 */

looks at the MSB of L1CSRn. It should look at the LSB.

I think the code should be something like this:

        andi.   r3,r3,1

or maybe:

	li	r4,1
	and	r3,r3,r4

if you dont want to touch CR0 (can you modify the CRs whenever you like?).

This reasoning is based on the description of the L1CSRn regs in my MPC8560 manual. I was wondering if this was correct for all MPC85xx processors, or just the 8560 (or maybe my manual is wrong, or I haven't seen an errata). Cheers!

								Murray...

--
Murray Jensen, CSIRO Manufacturing & Infra. Tech. Phone: +61 3 9662 7763
Locked Bag No. 9, Preston, Vic, 3072, Australia. Fax: +61 3 9662 7853
Internet: Murray.Jensen at csiro.au

To the extent permitted by law, CSIRO does not represent, warrant and/or guarantee that the integrity of this communication has been maintained or that the communication is free of errors, virus, interception or interference.

The information contained in this e-mail may be confidential or privileged. Any unauthorised use or disclosure is prohibited. If you have received this e-mail in error, please delete it immediately and notify Murray Jensen on +61 3 9662 7763. Thank you.

This is probably the way to go.

CR0 is volatile and thus can be used w/o saving it.

I recommend sending a patch to the list to fix this.

- kumar