[Buildroot] [PATCH] linux: handle read-only dts files

[Nikolay Dimitrov <picmaster@mail.bg>]

Hi Hollis,

On 08/12/2015 07:27 PM, Hollis Blanchard wrote:
> On 08/12/2015 09:11 AM, Nikolay Dimitrov wrote:
>> Hi Hollis,
>>
>> On 08/12/2015 07:02 PM, Hollis Blanchard wrote:
>>> The DTS exists at $(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH) because that's
>>> where it lives. It's copied to $(KERNEL_ARCH_PATH)/boot/dts/ so that the
>>> kernel build process can build a DTB out of it (which is later copied to
>>> build/images/).
>>>
>>> Or did I misunderstand the question?
>
> (Just to be clear: $(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH) is under version
> control, while $(KERNEL_ARCH_PATH), the build directory, is not.)
>
>> Sorry, I could've been probably more clear. My question was whether the
>> DTS needs to exist also at the destination ($(KERNEL_ARCH_PATH)/boot
>> /dts/) before the copying happens.
>
> It does not need to exist there. It's only there because of a previous
> cp in a previous build.

Ahh, now I see.

>
>> If it doesn't exist at the destination, the VCS wouldn't have checked
>> it out as r/o file, and the issue wouldn't happen in the first place
>> (e.g. the copy operation will succeed). Also, when we have 2 files with
>> the same name and content, this tends to create confusion with
>> developers (aka which file was the primary one).
>
> The file needs to exist at the destination at least temporarily, for the
> DTS->DTB translation. You could say "we should remove it afterwards",
> but a) that could be technically difficult in the face of ^C and kill
> -9, and b) you could say the same about zImage, vmlinux, etc... so we'd
> really be talking about a full "make clean", which seems like overkill.
>
> Are you suggesting "rm -f; cp" instead of "cp -f"? As far as I know the
> two are functionally equivalent, so the former seems like slightly more
> overhead to get the same effect as the latter.
>
> cp -f seems a simple solution: try harder to copy the file. :-)

Now your approach totally makes sense to me, thanks for taking your
time to explain it. I agree with your proposed fix.

>
> Hollis Blanchard
> Mentor Graphics Emulation Division

Kind regards,
Nikolay