Subject: Re: CONFIG_PROVE_LOCKING broken on 83xx (and all of powerpc?)

From: "Ira W. Snyder" <[email-masked]>
Date: Thu, 9 Sep 2010 12:36:42 -0700

On Thu, Sep 09, 2010 at 02:10:59PM -0500, Timur Tabi wrote:
> On Thu, Sep 9, 2010 at 1:44 PM, Ira W. Snyder <[email-masked]> wrote:
> 
> > Single stepping through the initial assembly portion of kernel startup
> > shows that the FDT gets clobbered during the function early_init(). This
> > trace is reproduced below.
> 
> Have you tried also enabling CONFIG_DEBUG_LOCK_ALLOC?  These two
> config options are related.
> 

Yes, I have had it enabled the whole time.

As noted in another email, it appears that U-Boot puts the FDT in such a
place that Linux overwrites it with the BSS. The CONFIG_PROVE_LOCKING=y
option expands the BSS by a large amount, which causes the error. It
isn't directly lockdep related.

I don't know if this is a U-Boot problem or a Linux problem. I have no
idea how to fix the bug.

Thanks,
Ira