From: David Gibson <david@gibson•dropbear.id.au>
To: Sebastian Andrzej Siewior <bigeasy@linutronix•de>
Cc: Milton Miller <miltonm@bga•com>, linuxppc-dev@ozlabs•org
Subject: Re: [PATCH] powerpc/boot: compare _start against ei.loadsize instead ei.memsize
Date: Tue, 14 Oct 2008 12:57:53 +1100 [thread overview]
Message-ID: <20081014015753.GD20620@yookeroo.seuss> (raw)
In-Reply-To: <20081013091526.GA9925@www.tglx.de>
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@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@gibson•dropbear.id.au>
--
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_!
http://www.ozlabs.org/~dgibson
next prev parent reply other threads:[~2008-10-14 1:57 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-23 20:38 [RFC] powerpc/boot: compare _start against ei.loadsize instead ei.memsize Sebastian Siewior
2008-09-24 1:46 ` Milton Miller
2008-09-25 10:21 ` Sebastian Siewior
2008-09-25 21:43 ` Sebastian Siewior
2008-10-10 3:58 ` Benjamin Herrenschmidt
2008-10-13 9:15 ` [PATCH] " Sebastian Andrzej Siewior
2008-10-14 1:57 ` David Gibson [this message]
2008-10-14 2:00 ` David Gibson
2008-11-01 20:00 ` [PATCH] powerpc/boot: allocate more memory for dtb Sebastian Andrzej Siewior
2008-11-06 0:16 ` David Gibson
2008-09-25 18:15 ` [RFC] powerpc/boot: compare _start against ei.loadsize instead ei.memsize Scott Wood
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