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Subject: Re: [PATCH V11 3/5] kbuild: Allow .dtso format for overlay source
 files
To:     Viresh Kumar <viresh.kumar@linaro.org>
Cc:     Masahiro Yamada <masahiroy@kernel.org>,
        Michal Marek <michal.lkml@markovi.net>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        David Gibson <david@gibson.dropbear.id.au>,
        Michal Simek <michal.simek@xilinx.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Anmar Oueja <anmar.oueja@linaro.org>,
        Bill Mills <bill.mills@linaro.org>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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From:   Frank Rowand <frowand.list@gmail.com>
Message-ID: <98697a33-a07d-6c5f-3f21-97a92ac68d3e@gmail.com>
Date:   Tue, 16 Mar 2021 00:36:32 -0500
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On 3/15/21 1:40 AM, Viresh Kumar wrote:
> On 14-03-21, 20:16, Frank Rowand wrote:
>> On 3/12/21 11:11 PM, Frank Rowand wrote:
>>> On 3/12/21 1:13 AM, Viresh Kumar wrote:
>>>> On 12-03-21, 01:09, Frank Rowand wrote:
>>>>> I suggested having the .dtso files include the .dts file because that is a relatively
>>>>> small and easy change to test.  What would probably make more sense is the rename
>>>>> the existing overlay .dts files to be .dtso files and then for each overlay .dtso
>>>>> file create a new .dts file that #includes the corresponding .dtso file.  This is
>>>>> more work and churn, but easier to document that the .dts files are a hack that is
>>>>> needed so that the corresponding .dtb.S files will be generated.
>>>>
>>>> What about creating links instead then ?
>>>>
>>>
>>> I don't really like the idea of using links here.
>>>
>>> Maybe it is best to make the changes needed to allow the unittest
>>> overlays to be .dtso instead of .dts.
>>>
>>> Off the top of my head:
>>>
>>>   scripts/Makefile.lib:
>>>      The rule for %.dtb.S invokes cmd_dt_S_dtb, which puts the
>>>      overlay data in section .dtb.init.rodata, with a label
>>>      pointing to the beginning of the overlay __dtb_XXX_begin and
>>>      a label pointing to the end of the overlay __dtb_XXX_end,
>>>      for the overlay named XXX.  I _think_ that you could simply
>>>      add a corresponding rule for %.dtbo.S using a new command
>>>      cmd_dt_S_dtbo (the same as cmd_dt_S_dtb, except use labels
>>>      __dtbo_XXX_begin and __dtbo_XXX_end).
>>
>> If you do the above, please put it in drivers/of/unittest-data/Makefile
>> instead of scripts/Makefile.lib because it is unittest.c specific and
>> not meant to be anywhere else in the kernel.
> 
> What about doing this then in unittest's Makefile instead (which I
> already suggested earlier), that will make everything work just fine
> without any other changes ?
> 
> +# Required for of unittest files as they can't be renamed to .dtso
> +$(obj)/%.dtbo: $(src)/%.dts $(DTC) FORCE
> +       $(call if_changed_dep,dtc)
> 

I should have looked at patch 3/5 more carefully instead of counting on
Masahiro to check it out and simply build testing.

Patch 3/5 does not seem correct.  I'll look over all the makefile related
changes that have been accepted (if any) and patch 3/5 later today (Tuesday).

-Frank