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Date: Tue, 25 Nov 2014 07:49:58 +0100
From: Sascha Hauer <s.hauer@pengutronix.de>
To: Andrew Lunn <andrew@lunn.ch>
Cc: Leif Lindholm <leif.lindholm@linaro.org>, devicetree@vger.kernel.org,
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        mark.rutland@arm.com, grant.likely@linaro.org, robh+dt@kernel.org,
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Subject: Re: [PATCH] of: support passing console options with stdout-path
Message-ID: <20141125064958.GK30369@pengutronix.de>
References: <1416867838-18652-1-git-send-email-leif.lindholm@linaro.org>
 <20141124230016.GP20238@lunn.ch>
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On Tue, Nov 25, 2014 at 12:00:16AM +0100, Andrew Lunn wrote:
> On Mon, Nov 24, 2014 at 10:23:58PM +0000, Leif Lindholm wrote:
> > Support specifying console options (like with console=ttyXN,<options>)
> > by appending them to the stdout-path property after a separating ':'.
> > 
> > Example:
> > 	stdout-path = "uart0:115200";
> > 
> > This patch also modifies of_find_node_by_path() to match only the
> > portion of the path before a ':'.
> 
> Hi Leif
> 
> These appears to somewhat conform to ePAPR, which says:
> 
>       A string that specifies the full path to the node representing
>       the device to be used for boot console output. If the character
>       ":" is present in the value it terminates the path.
> 
> So you can put any random junk after the :. However, are we going to
> have backward/forward compatibility problems, and problems with
> bootloaders? The current kernel code does not look for the :. So a new
> DT blob on an old kernel will not work so well.
> 
> More worrying, barebox does not support the : either. So there is a
> danger your bootloader suddenly goes silent after a dt blob update.

Since in barebox we use the upstream Kernel devicetrees it will be under
our control when they arrive, so we can add support for that ':'
before the new devicetrees arrive.

Sascha

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