Re: [ECOS] Debugging pc platform

[Andrew Lunn <andrew at lunn dot ch>]

On Wed, Mar 01, 2006 at 04:06:11PM +0000, David Fernandez wrote:
> On Tue, 2006-02-28 at 18:14 +0100, Andrew Lunn wrote:
> > On Tue, Feb 28, 2006 at 05:08:32PM +0000, David Fernandez wrote:
> > > 
> > > 	Hi there,
> > > 
> > > 	I'm trying to run eCos in a couple of pc platforms... At the moment,
> > > I've configured a pc_i82544 + redboot + FLOPPY_SMP, and running it on a
> > > 2 Xeon board and a 2 Pentium-S board, both SMP 1.4 and no ACPI.
> > > 
> > > 	I've found problems with the 2 Pentium-S board, unless disabling SMP
> > > support in eCos HAL \ i386 Architecture, it hangs just after loading
> > > from floppy.
> > > 
> > > 	I've enabled the SHOW_DIAGNOSTICS in pcmb_smp.c, and redirected Debug
> > > and Diagnostics to Port 2 (PC Screen). It prints a lot of messages and
> > > then stops with something similar to a GDB stream... None of the above
> > > messages seem to indicate an error, but I can't see them all.
> > 
> > Well the output to gdb will be interesting. Set the diagnostics to go
> > out the serial port and run gdb on the other end.
> > 
> > Something else to try is enable INFRA_DEBUG and see if an assert's
> > fail.
> > 
> >         Andrew
> 
> 	I've configured a minimal debugging environment at the moment.
> 	
> 	The debugger says that a SIGTRAP is the cause of the program stopping,
> the address is 0x665eabeb, and the stack frame shows a function with no
> arguments.

That address does not look very likely. I would guess the processor
has jumped to a random address, possibly because of stack
corruption/overflow, or a buffer overflow problem.

> 	I don't know how to configure the debugger to get more information,
> I've never debugged hal-like things in Linux. Do you now the core file
> that I should provide the debugger with, and what additional things need
> to be done?

You don't need a core file, just the ELF of the image you are
running. But since i think this address is outside of the image i
doubt it will be of much use.

> 
> 	I've activated "Asserts and Traces" in "Infracstructure", but nothing
> new is printed, only the smp information, that looks like everything is
> ok there so far, but the SIGTRAP keeps appearing.
> 
> 	Are there more things to turn debugging information on?

Try fully enabling stack checking.

Is it SMP which is causing the problem? Maybe try running SMP but hack
Cyg_Scheduler::start() so that it does not start the other CPUs. That
might tell you more....It might also be interesting to find out which
CPU has the problem. 

        Andrew

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