How to choose cache write policy on ppc

Question

Hello !

I'm optimizing a Linux boot on PowerPC MPC83xx. I'm trying to optimize the kernel image copy, from nand to ram and trying to check or change the write policy of the cache.

As a read in the reference manual, the processor uses the write-back policy by default. But I haven't found any register where to check/configure this.

How can I change this to do some test using the write-back/through policy ?

Thanks !

Answer 1

I believe the setting is actually in the MMU, not the cache per se.

There are 3 cache control bits for each configured region -- one of them is the write-through / write-back setting. Write back usually yields better performance. I forget the power-on default setting, but it's all in the data sheet.

Freescale Appnote AN3544 should be of help.