[U-Boot-Users] Problems writing to memory with mw

[Jerry Van Baren <gerald.vanbaren@ge.com>]

robert lazarski wrote:
> Hi all,
> 
> I'm trying to track down problems loading a linux kernel on my custom
> 8548 board off of 1.3RC3 - it loads sometimes via a ramdisk and gives
> me a bash shell - but most times it crashes in unusual, different
> places.
> 
> I ram mtest in the monitor and it crashes at 00000a90 . When using mw I get:
> 
> => mw 00000a90 cafecafe
> NIP: CAFECAFC XER: 00000000 LR: 1FFC109C REGS: 1ff9dc40 TRAP: 0700 DAR: 00000000
> MSR: 00001000 EE: 0 PR: 0 FP: 0 ME: 1 IR/DR: 00
> 
> GPR00: 1FFD9C44 1FF9DD30 00000200 1FF9DD40 00000338 00000018 1FFEA258 1FFEA308
> GPR08: 1FFEA2F0 1FF9E00C 00000C01 1FFA03F0 1FFEA250 00000000 1FFEFB00 20040000
> GPR16: 00000000 00000000 00000000 00000000 00001000 1FF9DD30 00000000 1FFC109C
> GPR24: CAFECAFE 1FFEA244 00000339 1FFE71B8 00000049 1FF9DF80 1FFF0860 00000338
> ** Illegal Instruction **
> Call backtrace:
> 00000000 1FFD6C80 1FFD74CC 1FFDB6A8 1FFDC0A4 1FFDC6D0 1FFD0AE0
> 1FFC8294 1FFC161C
> 
> I can write to  00000a90 via the bdi . u-boot otherwise runs
> perfectly. Any ideas?
> Robert

98% probability you have a SDRAM configuration problem.  2% probability 
you have a hardware problem.  I'm rooting for SDRAM config problem, you 
probably should too. ;-)
   <http://www.denx.de/wiki/view/DULG/UBootCrashAfterRelocation>

Writing to location 0x0A90 doesn't sound like a good idea to me.  I'm 
not familiar with the 8548, but this is in the middle of the exception 
vectors.  You are probably overwriting exception handling code (check 
your 85xx UM), so that would be an invalid test (red herring).

gvb