Re: SMP Pentium III, GA-6VXDC7 MoBo. -- 2.4.18-pre7 SMP not working

["W. Michael Petullo" <mike@flyn.org>]

> I have a home-built dual Pentium III computer which does not seem to
> want to run recent SMP kernels.  The computer is built on a Gigabyte
> GA-6VXDC7 motherboard, which is in turn based on a VIA Apollo Pro chip-set.
> It is an exclusively SCSI system -- I do not compile any IDE drivers
> into my kernel.
> 
> Kernel 2.4.12 works fine when compiled with SMP on.  However, anything
> newer fails to load when compiled with SMP support.  In the failing cases,
> lilo prints its uncompressing kernel and booting kernel messages followed
> by a system hang -- the kernel never prints anything.
> 
> Kernel.org
> Vanilla		CONFIG_SMP=y		# CONFIG_SMP is not set
> Version		SMP Status		UP Status
> ======================================================
> 2.4.10		SMP works		Fine
> 2.4.11		Wouldn't touch		Wouldn't touch
> 2.4.12		SMP Works		Fine
> 2.4.13		SMP does not boot	Fine
> 2.4.14		Did not try		Did not try
> 2.4.15		Did not try		Did not try
> 2.4.16		SMP does not boot	Fine
> 2.4.17		SMP does not boot	Fine
> 2.4.18-pre7		SMP does not boot	Fine
> 
> Since the kernel does not even peep an oops message, I'm not sure where
> to start debugging.  Is anyone else having similar problems?

I'm having a lot of trouble debugging this one.  Prinks are not being
displayed on the screen, though I know they are being executed.  I have
even tried William Lee Irwin's early_printk patch to try and get printks
to display.  Apparently the prink buffer is not being flushed this early
in the kernel code?

The only debugging technique I have found is to insert return statements
in order to avoid different sections of code.  I find, for example,
that if I make the first statement of the smpboot.c:do_boot_cpu a return,
the kernel will boot (without SMP on, of course).

Obviously, this is not the best technique.  I have been able to narrow
the location of the bug down a little with it, but I feel I will be able
to discover little more with this technique.

I'm not sure what else to do without printks.

I would appreciate any tips on debugging smpboot.c.

Thank you.

-- 
Mike

:wq