starting RAM adress for linux kernel

[scarayol at assystembrime.com]

Hello,

We have a platform similar to MPC885ADS (xith Kernel version 2.4.26) except
that :
- the RAM is at 0x0300 0000 (size 0x10000000)
- the flash is at 0x0280 0000 (size  0x00200000)
- IMMR = 0x0220 0000

After u-boot on MPC885ADS, we get the following platform information :
- RAM at 0 size 0x0080 0000
- FLASH at 0xFE00 0000  size 0x00200000
- IMMR at 0xFF00 0000

This information is different from the documentation of MPC885ADS :
- FLASH at 0x0280 0000  size 0x00800000
- IMMR at 0x0220 0000


1) in fads.h of u-boot, it is specified that RAM __must_ start at 0 : it
isn't true on our board :
- can linux work with RAM not beginning at 0 on this board ?
- what modifications should we make in the kernel to accept RAM at 0x0300
0000 ?

2) is brd_info the only structure given to kernel by u-boot ?
That is to say is it the only way for the kernel to have information about
the boad  ?

4) are the following values important if  CONFIG_HIGHMEM is not defined
(they are automatically generated by our Metrowerks PCS tool in autoconf.h
) ?
#define CONFIG_HIGHMEM_START 0xfe000000
#define CONFIG_LOWMEM_SIZE 0x30000000
#define CONFIG_KERNEL_START 0xc0000000
#define CONFIG_TASK_SIZE 0x80000000
Should we change these values  if  CONFIG_HIGHMEM is not defined ?

5) is the base value of IMMR very important (real value in u-boot different
from documentation) ?

Thanks really for your help.

Sophie CARAYOL.