Help request for PowerPC MPC855T MMU setup

jerryn — Tue, 05 Nov 2013 23:25:04 GMT

I am trying to upgrade a legacy device which is equipped with 32MB SDRAM

with 64MB SDRAM, using memory of the same family, form and fit..

When the main program is modified using the guesstimated settings, it does

not work. The issue appears to be in the MMU setup.

Not being familirar with setting this unit up, but making a stab at altering

the existing files was not successful.

The hardware has the correct jumpers for correct bank addressing of the

expanded memory range from 0xFE00 0000 to 0xFC00 0000

The application seems to be straight-forward as the address translations

from virtual to physical addresses are identical.

1. The BR1 and OR1 have been changed to access these new addresses.

The bootloader has been modified and appears to properly access the

new address space.

The main program is being tested without a bootloader to eliminate

that variable.

4. The BR1 and OR1 setting can be used with the original application

program, and runs normally

When either the MMU setup is changed and the linkage set for the

expanded memory, it does not run.

I have attached the original set up files and the altered files to

see if anyone can spot a glaring setup error(s). Any help would be

appreciated.

memory.h sets up BR1 and OR1

MMU_config sets up the TLBs

the *.dld files are the linker command files

Jerry

Original Attachment has been moved to: memory_64MB.h.zip

Original Attachment has been moved to: inkjet_64MB.dld.zip

Original Attachment has been moved to: memory_32MB.h.zip

Original Attachment has been moved to: MMU_config_64MB_RAM.c.zip

Original Attachment has been moved to: MMU_config_32MB_RAM.c.zip

Original Attachment has been moved to: inkjet_orig32MB.dld.zip

Re: Help request for PowerPC MPC855T MMU setup

jerryn — Thu, 07 Nov 2013 01:08:33 GMT

An update. Modifying the files for 48MB works. 56MB and 64MB do not. The issue seems to be with MMU_config.

Re: Help request for PowerPC MPC855T MMU setup

LPP — Fri, 08 Nov 2013 10:08:05 GMT

This processor provides 32 data and 32 instruction TLBs. Your MMU initialization tries to define more than 32 entries. 48MB requires less entries and thus it works.

Re: Help request for PowerPC MPC855T MMU setup

jerryn — Fri, 08 Nov 2013 17:14:32 GMT

Thank you for your answer. It is appreciated!!

topic Re: Help request for PowerPC MPC855T MMU setup in PowerQUICC Processors

Help request for PowerPC MPC855T MMU setup

Re: Help request for PowerPC MPC855T MMU setup

Re: Help request for PowerPC MPC855T MMU setup

Re: Help request for PowerPC MPC855T MMU setup