[Buildroot] [FYI] Bootlin external toolchains

[Arnout Vandecappelle]

On 03/12/2019 10:59, Romain Naour wrote:
> Hi Thomas, Vadim,
> 
> +Arthur Courtel in Cc.
> 
> Le 02/12/2019 à 15:26, Thomas Petazzoni a écrit :
>> Hello,
>>
>> +Romain Naour in Cc.
>>
>> On Mon, 2 Dec 2019 02:47:15 +0200
>> Vadim Kochan <vadim4j at gmail.com> wrote:
>>
>>> Just in case if someone will be interested. I started Buildroot external
>>> project which provides external toolchains from the Bootlin:
>>>
>>>     https://toolchains.bootlin.com
>>>
>>> The git repo can be found at:
>>>
>>>     https://github.com/vkochan/buildroot-external-toolchain-bootlin
>>
>> An effort was started to package the Bootlin external toolchains in
>> Buildroot itself, some time ago by engineers at Smile. We had some
>> off-list discussion about this, but I don't think it was ever posted to
>> the list. The idea back then was to have a script that generates all
>> the packages, but the design was to have one package for each
>> toolchain, so it really added a lot of packages.
>>
>> But I think we should really support these toolchains in Buildroot
>> proper instead of having an external for them.
> 
> Agree.
> 
> Arthur will take a look at the script but it's very complicated script...
> Maybe we need to discuss what we really want.

 I think this should be like scancpan/scanpypi, i.e. something that generates
the toolchain-external-bootlin package but it's up to the user to fix up the
final details.

 And then we can work on toolchains-builder to make sure it generates something
that is easier for this scanbootlin script to parse.

 Alternatively, maybe even better, we can just update build.sh in
toolchains-builder to generate all the pieces and then add an additional
pipeline stage that collects the pieces into a package.

 Most importantly, though, I think we should take this gradually. Start with a
manually constructed package, it doesn't even need to support all the different
toolchains. We can bikeshed a bit on what that package looks like, and use that
as input for how to script it.

 To kick off the bikeshedding, here's my opinion on what the package should look
like.

* It should be a single package, toolchain-external-bootlin. Maybe two (-stable
and -bleeding-edge) but I think there'll be enough shared infrastructure to
warrant creating a single package.

* It should offer a choice in Config.in.options for libc and stable/bleeding-edge.

* For now, it should be limited to *exactly* the same architecture suboptions as
what the toolchain was built for. Later we can decide how to expand this to
compatible options (e.g. the core-i7 toolchain will also work for core-avx2) -
but I'm pretty sure that that is something that will require help from
toolchain-builder itself.


 Regards,
 Arnout