[PATCH] powerpc/boot: compare _start against ei.loadsize instead ei.memsize

[David Gibson]

On Tue, Oct 14, 2008 at 12:57:53PM +1100, David Gibson wrote:
> On Mon, Oct 13, 2008 at 11:15:26AM +0200, Sebastian Andrzej Siewior wrote:
> > If the vmlinux binary in memory is larger than 4 MiB than it collides
> > with the initial boot code which is linked at 4 MiB in case of cuBoot.
> > If the the uncompressed image size (on disk size) is less than 4 MiB
> > then it would fit. The difference between those two sizes is the bss
> > section. In cuBoot we have the dtb embedded right after the data
> > section so it is very likely that the reset of the bss section (in
> > kernel's start up code) will overwrite the dtb blob. Therefore we
> > reallocate the dtb. Something similar is allready done to the initrd.
> > 
> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy at linutronix.de>
> 
> This patch looks sound to me.  It does strike me as only a stopgap
> until we come up with some better way of managing the early memory,
> preferably avoiding the magical fixed 4MiB (or whatever) offset.
> 
> Still, it looks safe - since it does check that the wrapper's malloc()
> region can't collide with the kernel's BSS.  So, if this little slice
> of extra BSS room is useful for the time being, I see no reason not to
> apply the patch.
> 
> Acked-by: David Gibson <david at gibson.dropbear.id.au>

Oh, one other thing.  Since we are now unconditionally copying the dtb
into a malloc()ed buffer, possibly it would be sensible to add a
little padding to the buffer at that point, so that further device
tree manipulations won't need to reallocate it.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
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