Trouble calling hardwaremain

[Eric W Biederman]

Ronald G Minnich <rminnich at lanl.gov> writes:

> 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.

For even more fun I have had a hardware glitch that caused the the
memory size to be set to 0 after initializing it, properly.  The copy
succeeded when I had no ram at all.  Of course I couldn't execute the
LinuxBIOS code.

Have you enabled the serial port?

There is a file ramtest.inc that you can included that will do a basic
sanity check on the ram to see if is working.  Usually that is a help
when brining up a new port.

Eric