Trouble calling hardwaremain

[Ronald G Minnich]

On Thu, 10 Oct 2002, Hieu T. Tran wrote:

> The resulting romimage seems to have successfully initialized memory
> and copied code from rom to ram, but seems to be stucked at the call
> to hardwaremain from crt0.  (Post code is 0xfd, which is right before
> the call).

the call may not be failing. What may be happening is that you saw the
last successful post code; the memory is configured wrong; and the system
failed when you jumped to hardwaremain. This is what makes this chipset so
frustrating.

> Anyone has a good idea as to why this call would possibly fail?  I'm
> assuming that SDRAM is successfully initialized because the copy operation
> to ram was successful (e.g. it didn't hang the system), but I'm not too
> sure.

You are right not to be sure. Often the copy operation can work but the
memory will fail when the processor tries to use it for a stack, for
example. Any operation that causes a burst to memory can cause trouble.
The chip is EXTREMELY sensitive to the SDRAM drive level settings.

ron