Re: [RFC:PATCH 3.6.0-rc1] dtc: Add -P option to dtc for Pre-Processing.

On 15/08/12 03:12, Tabi Timur-B04825 wrote:

On Tue, Aug 14, 2012 at 8:11 PM, David Gibson [off-list ref] wrote:

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On Mon, Aug 13, 2012 at 09:01:53AM +0100, Srinivas KANDAGATLA wrote:

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From: Srinivas Kandagatla <redacted>

This patch add pre-processing capablity to dtc based on status property.
Now the dtc has additional option -P to enable Pre-processing based on
status property.

The SOCS have lot of device tree infrastructure files which mark the
device nodes as disabled and the board level device tree enables them if
required. However while creating device tree blob, the compiler can
preprocess the nodes and exclude nodes marked as disabled, doing this
way will reduce the size of device tree blob.

IMHO, many devices that are marked as "disabled" in the DTS are
expecting to be enabled by the boot loader, so just because a node is
disabled in the DTS does not mean that it will be disabled when Linux
sees it.

Good to know that,
But some of the secured bootloaders like the one's we use don't even
touch the dt blob.

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In our case this has reduced the blob size from 29K to 15K.

I don't see that as significant.

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Also nodes with status="disabled" is are never probed by dt platform bus
code.

Again, Preprocessing is optional parameter to dtc.

Using this option would break a lot of our device trees.

As this is optional parameter, I did not expect it to break the
default/existing behavior.
Correct me am missing anything?

  Perhaps it
should be given a better name, like --strip-disabled.

Thanks for the advice. I agree, Will be reposting the patch making this
option as --strip-disabled with CC to Jon Loeliger (dtc maintainer).