Linux 2.4.27-pre6-bk hangs on MPC8540 board

Wolfgang Denk wd at
Fri Aug 13 00:07:45 EST 2004

In message <EE7CAF713952AC4A970DD7CD8B4C12A042DCA7 at> you wrote:
> We are bringing up an 8540-based board, and are getting hangs at random
> spots when booting Linux.  Sometimes the hangs occur while the kernel is
> initializing, sometimes the boot gets far enough where I can log in and
> run a couple of programs.  Eventually the board locks up with no oopses
> or panics.  If I connect to the board with a debugger, the processor is
> usually stopped in the Data miss exception handler, and there is usually
> memory corruption in the kernel code.

That's it: memory problems.

> I ran memory tests using both Edink and U-boot and they all passed, so
> I'm reluctant to blame hardware for the memory corruption.  Has anyone
> seen similar behavior, or have any suggestions of things I might try?

All those memory tests only can test simple read and write  accesses;
they  all  fail to access burst mode accesses, which will happen when
Linux starts runing, and which are failing.

Your SDRAM initialization is bad, and  the  system  crashes  when  it
tries to fetch instructions from RAM. Note that simple read and write
accesses may still work, it's the burst mode that is failing.

It is NOT sufficient to program the memory controller  of  your  CPU;
each  SDRAM  chip  also  requires  a specific initialization sequence
which you must adhere  to  to  the  letter  -  check  with  the  chip
manufacturer's manual.

Best regards,

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at
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