ARM_ATAG_DTB_COMPAT fails on fdt_ro.c compiling

[Stephen Warren]

On 10/11/2012 01:24 AM, Shawn Guo wrote:
> On Tue, Oct 09, 2012 at 01:21:02PM -0300, Fabio Estevam wrote:
>> On Tue, Oct 9, 2012 at 1:15 PM, Stephen Warren <swarren at wwwdotorg.org> wrote:
>>
>>>>> I just tried building mainline now.  It is at commit f5a246eab9.
>>>>>
>>>> The build still fails for me at this commit.
>>>
>>> I can't reproduce this.
>>
>> Same here. It builds fine for me.
>>
> Thanks all for confirming it works.
> 
> I just figured it out on my end.  Here is how it gets broken for me.
> 
> - Before commit cd29672 (dtc: import latest upstream dtc) gets in,
>   I did a build without O=<output_dir>.  It results in a copy of those
>   libfdt files in arch/arm/boot/compressed.
> 
> - After the commit gets in, I start a build with O=imx parameter.  When
>   compiling imx/arch/arm/boot/compressed/fdt_ro.c, the #include <libfdt.h>
>   in fdt_ro.c seems to match the one left in arch/arm/boot/compressed/
>   from last build rather than imx/arch/arm/boot/compressed/libfdt.h.
> 
> Cleaning the libfdt copies in arch/arm/boot/compressed fixes the
> problem.

> Not sure why it's not "libfdt.h" but <libfdt.h> is used as
> the inclusion though, since the .h and .c are in the same folder.

I imagine that's because the libfdt code is set up to support being
built as a standalone library. In that case, <fdt.h> and <libfdt.h> are
presumably the public interface to the library, and would hence be
installed into /usr/include or similar. Still, I guess the libfdt source
itself would still work with "libfdt.h" rather than <libfdt.h>.

Note that looking at git history, fdt_ro.c included <libfdt.h> even
before cd29672 (dtc: import latest upstream dtc), and
arch/arm/boot/compressed/Makefile included fdt_ro.c before that commit,
so I'm not sure why the problem only shows up now? Perhaps anything that
caused your objects to be stale, and hence get rebuilt, would have
caused the issue.