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From: andrew@lunn.ch (Andrew Lunn)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] of: support passing console options with stdout-path
Date: Tue, 25 Nov 2014 00:00:16 +0100	[thread overview]
Message-ID: <20141124230016.GP20238@lunn.ch> (raw)
In-Reply-To: <1416867838-18652-1-git-send-email-leif.lindholm@linaro.org>

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.

Would it be safer to add a new property in chosen?

      Andrew

WARNING: multiple messages have this Message-ID (diff)
From: Andrew Lunn <andrew-g2DYL2Zd6BY@public.gmane.org>
To: Leif Lindholm <leif.lindholm-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	mark.rutland-5wv7dgnIgG8@public.gmane.org,
	grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org,
	robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
	plagnioj-sclMFOaUSTBWk0Htik3J/w@public.gmane.org,
	ijc-8fiUuRrzOP0dnm+yROfE0A@public.gmane.org
Subject: Re: [PATCH] of: support passing console options with stdout-path
Date: Tue, 25 Nov 2014 00:00:16 +0100	[thread overview]
Message-ID: <20141124230016.GP20238@lunn.ch> (raw)
In-Reply-To: <1416867838-18652-1-git-send-email-leif.lindholm-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>

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.

Would it be safer to add a new property in chosen?

      Andrew
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WARNING: multiple messages have this Message-ID (diff)
From: Andrew Lunn <andrew@lunn.ch>
To: Leif Lindholm <leif.lindholm@linaro.org>
Cc: devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, mark.rutland@arm.com,
	grant.likely@linaro.org, robh+dt@kernel.org,
	plagnioj@jcrosoft.com, ijc@debian.org
Subject: Re: [PATCH] of: support passing console options with stdout-path
Date: Tue, 25 Nov 2014 00:00:16 +0100	[thread overview]
Message-ID: <20141124230016.GP20238@lunn.ch> (raw)
In-Reply-To: <1416867838-18652-1-git-send-email-leif.lindholm@linaro.org>

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.

Would it be safer to add a new property in chosen?

      Andrew

  reply	other threads:[~2014-11-24 23:00 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-24 22:23 [PATCH] of: support passing console options with stdout-path Leif Lindholm
2014-11-24 22:23 ` Leif Lindholm
2014-11-24 23:00 ` Andrew Lunn [this message]
2014-11-24 23:00   ` Andrew Lunn
2014-11-24 23:00   ` Andrew Lunn
2014-11-25  0:12   ` Leif Lindholm
2014-11-25  0:12     ` Leif Lindholm
2014-11-25  0:12     ` Leif Lindholm
2014-11-25  6:49   ` Sascha Hauer
2014-11-25  6:49     ` Sascha Hauer
2014-11-25  6:49     ` Sascha Hauer
2014-11-25 14:44   ` Grant Likely
2014-11-25 14:44     ` Grant Likely
2014-11-25 14:44     ` Grant Likely
2014-11-25 16:21     ` Andrew Lunn
2014-11-25 16:21       ` Andrew Lunn
2014-11-25 16:21       ` Andrew Lunn
2014-11-25 10:35 ` Mark Rutland
2014-11-25 10:35   ` Mark Rutland
2014-11-25 10:35   ` Mark Rutland
2014-11-25 11:17   ` Leif Lindholm
2014-11-25 11:17     ` Leif Lindholm
2014-11-25 12:07     ` Ian Campbell
2014-11-25 12:07       ` Ian Campbell
2014-11-25 12:07       ` Ian Campbell
2014-11-25 14:35       ` Leif Lindholm
2014-11-25 14:35         ` Leif Lindholm
2014-11-25 14:35         ` Leif Lindholm
2014-11-25 14:55       ` Grant Likely
2014-11-25 14:55         ` Grant Likely
2014-11-25 12:54   ` Sascha Hauer
2014-11-25 12:54     ` Sascha Hauer
2014-11-25 12:54     ` Sascha Hauer
2014-11-25 14:58 ` Grant Likely
2014-11-25 14:58   ` Grant Likely
2014-11-25 14:58   ` Grant Likely
2014-11-25 15:15   ` Leif Lindholm
2014-11-25 15:15     ` Leif Lindholm
2014-11-25 15:20     ` Grant Likely
2014-11-25 15:20       ` Grant Likely
2014-11-25 15:24       ` Ian Campbell
2014-11-25 15:24         ` Ian Campbell
2014-11-25 15:39         ` Grant Likely
2014-11-25 15:39           ` Grant Likely
2014-11-25 15:39           ` Grant Likely
2014-11-25 15:41           ` Ian Campbell
2014-11-25 15:41             ` Ian Campbell
2014-11-25 15:41             ` Ian Campbell

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