Hi all,

recently I upgraded my Siemens SE505 router from 8MB RAM to 32MB and from 4MB Flash to 8MB. RAM works fine but Flash makes some trouble. First of all CFE didn't like the Toshiba top boot flashes I use, so I had to compile my own CFE with support for these devices. It works fine now but only for the lower 4MB (0x1c000000 to 0x1c3fffff), the upper 4MB are mirrored to the lower 4MB. I checked A21 of the flash and found out that it's doing nothing. It looks like it's routed to the CPU (really hard to say on a multilayer PCB) but I'm not sure.

My question is if I have to configure the CPU to give me access to more than 4MB. I know from other MIPS based CPU's that they start with external bus access from 0xbfc00000 to 0xbfffffff. If I want to access more Flash I have to set the channel base address and channel size.

Is there something similar inside the BCM4712 or is my A21 line just not routed?

Since BROADCOM documentation is not available any help is appreceated.

Regards