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

From: Benjamin Herrenschmidt <[email-masked]>
Date: Fri, 10 Sep 2010 08:16:18 +1000

On Fri, 2010-09-10 at 08:13 +1000, Benjamin Herrenschmidt wrote:
> On Thu, 2010-09-09 at 17:11 -0500, Scott Wood wrote:
> > > I would have expected uboot to warn (the kernel ELF header contains
> > the
> > > BSS size) but apparently that isn't the case.
> > 
> > U-Boot doesn't use ELF files with Linux, so it has no idea where the
> > BSS is.  uImage is just a wrapper around a flat binary.
> 
> Oh, right, I forgot about that... -1 for uboot there. Seriously, it's
> time it grows the ability to load ELF or to at least stick an ELF in a
> uImage... I've never understood the reasoning for that uImage wrapper
> thingy. Definitely causes more problems than it solves in my experience.

Note that with ePAPR we know the top of mapped memory on entry, so
in theory, if the bootloader is fully ePAPR compliant we -could- detect
that case and move the FDT up to after the .dts before we clear the
bss... do we care enough tho ?

Even if we aren't totally ePAPR compliant, we could still try to move
it, if we hit the end of memory well... we won't do more damage than we
already did by by overwriting the dts in the first place.

Cheers,
Ben.