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

[robert lazarski <robertlazarski@gmail.com>]

On Nov 20, 2007 9:54 AM, Jerry Van Baren <gerald.vanbaren@ge.com> wrote:
>
> 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
<snip>
> >
> > 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
>

Ahh, seems my test is invalid - thanks for pointing that out. I
defined and ran my boards testram() succesfully when I brought the
board up - that seems to write to 0x0A90 et all when its safe to do
so. I'll try again but its a long test.

I see no problems with u-boot - relocation seems to work. The link
suggested following my memory specs "to the letter" . So far I'm just
calling spd_sdram() like most 85xx boards do - should I look there?
Since my kernel boots sometimes into bash, but usually doesn't, I'm
trying to confirm my memory is functioning. When the kernel fails to
boot the eldk 85xx uRamdisk, its crashes at several different places
before it loads the RFS. A few times everything just worked fine,
which makes me think its a hardware issue. Any suggestions to tracking
that type of problem down?

Thanks, Robert