[Buildroot] [RFC PATCH v3 00/10] Make the SDK relocatable

[Wolfgang Grandegger]

Am 28.06.2017 um 00:41 schrieb Arnout Vandecappelle:
> 
> 
> On 27-06-17 12:54, Wolfgang Grandegger wrote:
>> Hello,
>>
>> Am 21.06.2017 um 23:06 schrieb Arnout Vandecappelle:
>>>
>>>
>>> On 21-06-17 23:03, Arnout Vandecappelle wrote:
>>>>    Preferably as an instrumentation hook, because:
>>>> - it speeds things up dramatically if you do 'make foo-rebuild';
>>>> - things are still correct if you interrupt the build in the middle;
>>>> - it makes no difference if you do a rebuild (if patchelf is done at the end,
>>>> and then you rebuild a package, the RPATH in the libs you link with is different
>>>> than the first time you built it).
>>>
>>>    Note, however, that doing it as an instrumentation hook could be a pretty
>>> dramatic rewrite of your series, so if you don't feel up to it, I'm ok with
>>> committing the current approach to begin with.
>>
>> I just sent out v4 of my patch series doing the sanitation at the end of the
>> build. Yes, using GLOBAL_INSTRUMENTATION_HOOKS would requires further
>> modification to the framework. But also "check-bin-arch" and "check-host-rpath"
>> does a lot of useless scanning for ELF files.
>> Therefore it would make sense to use this mechanism to create a list of ELF
>> files similar to the hook "step_pkg_size" (creating packages-file-list.txt),
>> either per installation step or even better per package:
>>
>>    build/target-packages-elf-files.txt
>>    build/staging-packages-elf-files.txt
>>    build/host-packages-elf-files.txt
>>
>> or (per package)
>>
>>    build/elf-file-list/<host|staging|target>-<package>-elf-files.txt
> 
>   I definitely like the per-package file list, because it smoothly scales to
> per-package-staging. Ideally then the packages-file-list.txt should also be
> split into a separate list per package. From there it's a small step to have an
> elf-file list as well.
> 
>   Since it's anyway per-package, I'd put it directly in the package build
> directory, e.g. $(@D)/.<host|staging|target>-files.txt and
> $(@D)/.<host|staging|target>-elf-files.txt.

OK, into $($(PKG)_DIR).

>   But as I understand it, your proposal is to commit your series as is, with the
> scanning done only in the finalize step, and refactor it with elf files lists later?

That would be a good starting point. The per package sanitation requires 
quiet some changes to the build infrastructure.

>> If we do not need the per package list lateron, we could create it
>> temporarily, call "fix-rpath" to do the sanitation and delete it afterwards. Or,
>> even simpler, fix-rpath could work on ".br_filelist_before" and
>> ".br_filelist_after" directly... that seems not too difficult to implement. What
>> do you think?
> 
>   The latter was actually what I had in mind: refactor the step_pkg_size_end to
> save the output of comm in a temporary file, and use that file to call the
> fix-rpath script. That temporary file is basically $(@D)/.target-files.txt.

I already started to implement that approach... more soon.

Wolfgang.