From: Maxime Ripard <maxime.ripard@free-electrons.com>
To: Alexander Shiyan <shc_work@mail.ru>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH] Revert "ARM: Use armlinux_bootparams address for DTB"
Date: Wed, 7 Aug 2013 14:40:54 +0200 [thread overview]
Message-ID: <20130807124054.GF2911@lukather> (raw)
In-Reply-To: <1375877184.576122343@f176.i.mail.ru>
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On Wed, Aug 07, 2013 at 04:06:24PM +0400, Alexander Shiyan wrote:
> > On Wed, Aug 07, 2013 at 01:55:42PM +0400, Alexander Shiyan wrote:
> > > > This patch placed the flattened devicetree to armlinux_bootparams.
> > > > armlinux_bootparams normally is at SDRAM_START + 0x100. The kernels
> > > > initial page tables are normally at SDRAM_START + 0x4000, so the
> > > > flattened devicetree gets overwritten once it exceeds 0x3f00 bytes
> > > > which is quite common.
> > > >
> > > > Revert this patch for now once a better solution can be found
> > >
> > > In such a case, tree may be placed immediately after the kernel?
> > > It can also serve as an automatic option "ARM_APPENDED_DTB".
> >
> > That won't work either, since the DTB will be overwritten by the kernel
> > decompressor.
>
> arch/arm/Kconfig:
> ...
> config ARM_APPENDED_DTB
> bool "Use appended device tree blob to zImage (EXPERIMENTAL)"
> depends on OF && !ZBOOT_ROM
> help
> With this option, the boot code will look for a device tree binary
> (DTB) appended to zImage
> (e.g. cat zImage <filename>.dtb > zImage_w_dtb).
> ...
>
> So, DTB is placed immediately after the kernel.
Yes, in the case where you have APPENDED_DTB, the decompressor relocates
the DTB before doing the decompression.
The trouble is when you don't have APPENDED_DTB enabled, when there is
no such relocation happening.
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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prev parent reply other threads:[~2013-08-07 12:41 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-07 9:45 Sascha Hauer
2013-08-07 9:55 ` Alexander Shiyan
2013-08-07 10:11 ` Sascha Hauer
2013-08-07 10:34 ` Alexander Shiyan
2013-08-08 7:17 ` Alexander Shiyan
2013-08-09 6:58 ` Sascha Hauer
2013-08-09 7:02 ` Alexander Shiyan
2013-08-09 8:02 ` Sascha Hauer
2013-08-07 11:37 ` Maxime Ripard
2013-08-07 12:06 ` Alexander Shiyan
2013-08-07 12:40 ` Maxime Ripard [this message]
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