ppc32 kernel boot problem (pmu related?)

[Benjamin Herrenschmidt]

On Tue, 2006-05-16 at 11:04 -0400, Nathan Pilatzke wrote:
> On 5/16/06, Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote:
> >
> > Can you try editing arch/powerpc/platforms/powermac/low_i2c.c, in
> > function pmac_i2c_init(), comment out the call to pmac_i2c_devscan() and
> > tell me if that makes a difference.
> >
> > Thanks,
> > Ben.
> >
> >
> Commenting out the call to pmac_i2c_devscan() in function
> pmac_i2c_init() allowed the kernel to boot.  I am typing this email
> booted under it.  The kernel messages were printed a bit strangely
> though.  There was no scrolling or clearing of the screen.  The kernel
> messages would start at the top and overwrite old messages, with the
> cursor jumping back to the top of the screen every so often.

That's because of the change you did to udbg.c for debugging :)

> The /proc/device-tree is attached for the booting 2.6.17-rc3 kernel with
> pmu enabled, as is the new dmesg output.  If you need the
> /proc/device-tree from a 2.6.15 working kernel with pmu enabled
> instead, let me know.

No, it should be the same regardless of the kernel

> Is this kernel fairly safe/stable to use?  What can be done next?

Well, I need to figure out what's going on with the i2c stuff... there
is a chip that hangs off the PMU and that says something like "do that
at boot"... but when I do it, it causes the crash you are seeing. So
either I'm not doing what it tells me to do properly or I should just
blacklist this machine (Apple doesn't execute the platform functions
from the device-tree on older machines I think).

I'm investigating, will come back to you.

Ben.