[U-Boot-Users] Memory Access Problem

[Muhammad Sarwar]

kernel is not be mapping this address (0x2200A000) by itself. As you're mapping LED base to a user space virtual address, the easiest solution would be if you can have your LED base at physical in the already mapped range. Somewhere above 0xe0000000 for example. Then you'll have phys=virtual...no mapping required.

Another way is to map LED base where it is physically but have it mapped somewhere for example above 0xf0000000 and then you have to change the mapping in the xxxx_map_io() function in arch/ppc/kernel/xxxx_setup.c to account for this.


Regards,
 
Muhammad Sarwar
Mangrove Systems Inc.

-----Original Message-----
From: sudhakar rajashekhara [mailto:rsudhakar_blr at yahoo.com] 
Sent: Tuesday, February 24, 2004 11:27 AM
To: u-boot-users at lists.sourceforge.net
Subject: [U-Boot-Users] Memory Access Problem

Hi,

We have ported U-boot and Linux to a custom 8280
board. For this board, the LED base has been set at
0x2200A000. I am able to write to this base from
U-boot using mw command and control the LED display.
But if I try to access the same memory from Linux, the
kernel is raising an exception. I even tried to map
this memory area by calling ioremap in MMU_init but
the result was same. Do I have to do any other
configuration in the Linx kernel to access this memory
area? Following is the log:

regards,
Sudhakar.

=======================================================
Oops: kernel access of bad area, sig: 11

NIP: C0139034 XER: 00000000 LR: C0139024 SP: C05B9F90
REGS: c05b9ee0 TRAP: 0300
   Not tainted

MSR: 00009032 EE: 1 PR: 0 FP: 0 ME: 1 IR/DR: 11

DAR: 2200A000, DSISR: 22000000

TASK = c05b8000[1] 'swapper' Last syscall: -1

last math 00000000 last altivec 00000000

GPR00: FFFFFFFF C05B9F90 C05B8000 C0110000 00001032
00000001 00000001 00000000

GPR08: F0000088 2200A000 C012D417 C05B9EA0 C0170000
00000000 10000000 00000000
GPR24: 00000000 00000000 40000000 007FFF7E 007FFF00
00000000 C0170000 007FFEB0
Call backtrace:
=======================================================

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