linux-kernel - Re: DTB build failure due to preproccessing

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Date:	Fri, 31 May 2013 10:37:43 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Ian Campbell <Ian.Campbell@...rix.com>
CC:	linux-kernel <linux-kernel@...r.kernel.org>,
	linuxppc-dev@...ts.ozlabs.org, Michal Marek <mmarek@...e.cz>,
	Stephen Warren <swarren@...dia.com>,
	Rob Herring <rob.herring@...xeda.com>,
	Grant Likely <grant.likely@...retlab.ca>,
	JonLoeliger <jdl@....com>, linux-kbuild@...r.kernel.org
Subject: Re: DTB build failure due to preproccessing

On 05/31/2013 04:29 AM, Ian Campbell wrote:
> This affects arch/powerpc/boot/dts/virtex440-ml510.dts but I think it is
> actually a more general issue:
> 
>         $ make ARCH=powerpc CROSS_COMPILE=powerpc-linux- virtex440-ml510.dtb 
>           CC      scripts/mod/devicetable-offsets.s
>           GEN     scripts/mod/devicetable-offsets.h
>           HOSTCC  scripts/mod/file2alias.o
>           HOSTLD  scripts/mod/modpost
>           DTC     arch/powerpc/boot/virtex440-ml510.dtb
>         Error: arch/powerpc/boot/dts/virtex440-ml510.dts:374.6-7 syntax error
>         FATAL ERROR: Unable to parse input tree
>         make[1]: *** [arch/powerpc/boot/virtex440-ml510.dtb] Error 1
>         make: *** [virtex440-ml510.dtb] Error 2
...
>            interrupt-map = <
>         # 375 "arch/powerpc/boot/dts/virtex440-ml510.dts"
>             0x3000 0 0 1 &xps_intc_0 3 2
>             0x3000 0 0 2 &xps_intc_0 2 2
>             0x3000 0 0 3 &xps_intc_0 5 2
>             0x3000 0 0 4 &xps_intc_0 4 2

I /think/ what's happening here is that dtc's rule for #line parsing
allows the formats:

# LINE FILENAME
or:
#LINE FILENAME FLAGS

where FLAGS is an integer

The lexer rule that optionally consumes flags requires some WS
(white-space) between the filename and flags. It looks like this
whitespace can actually cross a line boundary, so it ends up consuming
the first "0" of the hex constant on the next line, which then leaves
"x3000" to be parsed as cell data, which is a syntax error.

You can hack around this for testing by doing one of a few things:

a) Add an extra integer on to the end of the problematic #line directives.

b) Remove the leading "0x" from the constants following the #line
directives. I think this will still mean dtc eats the 3000 as part of
the #line directive, but hides the syntax error.

The solution here is to make dtc's #line matching regex:

<*>^"#"(line)?{WS}+[0-9]+{WS}+{STRING}({WS}+[0-9]+)? {

... use someting other than {WS} in the final instance; some kind of
{WS} that won't match/cross line boundaries. I'll see if I can cook up a
patch for this.
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