From: Sascha Hauer <s.hauer@pengutronix.de>
To: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Tomasz Figa <t.figa@samsung.com>,
devicetree-discuss@lists.ozlabs.org,
linux-samsung-soc@vger.kernel.org,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
kgene.kim@samsung.com, thomas.abraham@linaro.org,
bones@secretlab.ca, linux-arm-kernel@lists.infradead.org
Subject: Re: Early kernel hang with big DTB appended
Date: Tue, 15 Jan 2013 11:53:49 +0100 [thread overview]
Message-ID: <20130115105349.GK1906@pengutronix.de> (raw)
In-Reply-To: <alpine.LFD.2.02.1301141655570.6300@xanadu.home>
On Mon, Jan 14, 2013 at 05:13:09PM -0500, Nicolas Pitre wrote:
> On Fri, 11 Jan 2013, Sascha Hauer wrote:
>
> > On Thu, Jan 03, 2013 at 04:55:00PM +0100, Tomasz Figa wrote:
> > > Hi,
> > >
> > > I'm observing strange behavior when booting 3.8-rc1 and -rc2 with appended
> > > DTB. The kernel hangs very early when the DTB is bigger than some
> > > threshold somewhere around 24 KiB. With fullest possible low level UART
> > > debugging (and printk patched to use printascii) I'm receiving following
> > > output:
> > >
> > > Uncompressing Linux... done, booting the kernel.
> > > Booting Linux on physical CPU 0xa00
> > > Linux version 3.8.0-rc1-00073-gdf6efca-dirty (t.figa@amdc1227) (gcc
> > > version 4.5.2 (Gentoo 4.5.2 p1.2, pie-0.4.5) ) #2 SMP PREEMPT Thu Jan 3
> > > 15:37:35 CET 2013
> > > CPU: ARMv7 Processor [413fc090] revision 0 (ARMv7), cr=10c53c7d
> > > CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
> > >
> > > I tested on two Exynos-based boards (exynos4210-trats and one internal
> > > exynos4412-based board) and same happens on both.
> > >
> > > Do you have any ideas?
> >
> > Another thing besides the things already mentioned is that the dtb may
> > not cross a 1MiB boundary. The Kernel uses a single 1Mib section
> > (aligned to 1Mib) to initially map the dtb. Once you cross that boundary
> > parts of the dtb won't be accessible for the Kernel anymore.
>
> Crap. You're right. This patch should fix this issue.
Just successfully tested with a devicetree explicitly located just before a 1MiB
boundary, so:
Tested-by: Sascha Hauer <s.hauer@pengutronix.de>
Sascha
>
> @Tomasz: please could you confirm this fixes your initial problem?
>
>
> diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
> index 4eee351f46..61fcb18c7e 100644
> --- a/arch/arm/kernel/head.S
> +++ b/arch/arm/kernel/head.S
> @@ -246,6 +246,7 @@ __create_page_tables:
>
> /*
> * Then map boot params address in r2 if specified.
> + * We map 2 sections in case the ATAGs/DTB crosses a section boundary.
> */
> mov r0, r2, lsr #SECTION_SHIFT
> movs r0, r0, lsl #SECTION_SHIFT
> @@ -253,6 +254,8 @@ __create_page_tables:
> addne r3, r3, #PAGE_OFFSET
> addne r3, r4, r3, lsr #(SECTION_SHIFT - PMD_ORDER)
> orrne r6, r7, r0
> + strne r6, [r3], #1 << PMD_ORDER
> + addne r6, r6, #1 << SECTION_SHIFT
> strne r6, [r3]
>
> #ifdef CONFIG_DEBUG_LL
>
--
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next prev parent reply other threads:[~2013-01-15 10:53 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-03 15:55 Early kernel hang with big DTB appended Tomasz Figa
2013-01-03 18:40 ` Bryan Evenson
2013-01-04 10:26 ` Tomasz Figa
2013-01-04 2:48 ` Nicolas Pitre
2013-01-04 10:18 ` Tomasz Figa
2013-01-14 8:45 ` $(make uImage) is stupid [Was: Re: Early kernel hang with big DTB appended] Uwe Kleine-König
2013-01-11 16:45 ` Early kernel hang with big DTB appended Sascha Hauer
2013-01-14 22:13 ` Nicolas Pitre
2013-01-15 10:53 ` Sascha Hauer [this message]
2013-01-15 11:26 ` Tomasz Figa
2013-01-15 18:12 ` Nicolas Pitre
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