alan.corp.packetengines.com wrote: >I tried using the MD_CAM and MD_RAMn registers to debug this. These seem to >read back the values I have stored via the MD_RPN, MD_TWC and MD_RPN register >EXCEPT that when I read back I get a value for the MD_CAM.PS field of 110 >rather than the 111 which is the documented 8MB page size value. The doc even >says that values other than those listed (000, 001, 011, 111) are "reserved". >The value I am setting in the MD_TWC.PS field (which is oddly a two bit >encoding for page size) is 11, which is documented as the 8MB page >size value.
This is simple :-) Or rather, I was tearing my hair out last week trying to figure out exactly the same thing. Set the 4/16k bit in MD_RPN to 1 and it'll work. Apparently, the two page size bits in MD_TWC and the bit fr?n MD_RPN together form the real page size. The documentation is a bit misleading here. Now I'd just like to know why I can't get 8 MB pages working with the Linux page tables. The performance boost from putting the Linux kernel in an 8 MB page on a MPC850 is rather impressive, most lmbench system call benchmarks went twice as fast. /Christer -- Christer Weinigel Cendio Systems AB Email: wingel at cendio.se Teknikringen 8 Phone: +46-13-21 46 00 583 30 Link?ping Fax: +46-13-21 47 00 Sweden [please note that Signum Support has changed its name to Cendio Systems] ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
