[Buildroot] [FYI] Bootlin external toolchains

Romain Naour romain.naour at smile.fr
Wed Dec 4 21:52:05 UTC 2019


Hi Arnout, All,

Le 03/12/2019 à 22:15, Arnout Vandecappelle a écrit :
> 
> 
> 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.

The initial goal was to use toolchain bootlin as prebuilt external toolchain
when no other prebuilt toolchain is available (Linaro, Mentor etc...).
I would like to avoid letting the user fixing the final details.

> 
>  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.

The script evoked by Thomas showed that it was too difficult/complex to generate
a toolchain packages from the files currently provided by toolchain-builder.

So, I'm agree that it would be better if toolchain-builder can provide such 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.

At least aarch64, arm and x86_64 should be included in the manually constructed
package.

> 
>  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.

The most difficult part is to generate the dependencies (depends on) of the
toolchain and its properties (select). That is why our experimental script
create one package for each toolchain provided by toolchain Builder.

Also if we can use a single a single package for the Bootlin toolchain package,
it mean that we can also use a single package for the
Linaro/ARM/Codescape/Codesourcery packages.

> 
> * 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.

Indeed.

Best regards,
Romain

> 
> 
>  Regards,
>  Arnout
> 



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