[Buildroot] ARC support in Buildroot

[Thomas Petazzoni]

Hello Alexey,

On Thu, 3 Aug 2023 07:59:56 +0000
Alexey Brodkin via buildroot <buildroot at buildroot.org> wrote:

> > Can we drop those special versions and assume what's in upstream
> > GCC/binutils/GDB is good enough?  
> 
> Well, we'll just update it to say 2023.03 [1] or maybe even 2023.09 later
> in the fall :)

Looking forward to your patch doing this.

> And the reason is that ARCv3 support. As I mentioned ARCompact/ARCv2 is
> well supported in upstream GCC/Binutils/GDB etc and all the fixes go right
> to the upstream repos as we have our own maintainers who take care of that.
> 
> So, in theory it should be OK to remove "arc-xxxx.yy" toolchains from Buildroot.
> But since we were a bit late with ARCv3 changes for GCC 13, those will only
> land in GCC 14 which is going to happen sometime in 2024, I guess.
> 
> Thus, we'll need to have "arc-xxxx.yy" anyway with sources from our GitHub
> forks, primarily to support ARCv3 stuff. Thus, I didn't want to introduce that
> turbulence with removal of ARC toolchain and then adding it back next week.

Sounds good to me, but it should be maintained then :-)

> > (1) Drop ARC-specific versions of GCC/binutils/GDB if you confirm it's OK  
> 
> As I said, we'll update ARC toolchain instead:
>  - Primarily to add ARCv3 support and while ARC toolchian will be there anyway
>  - It makes sense to keep it for ARCompact/ARCv2 as there're some fixes and
>    improvements which are not yet upstream (because release schedules don't match)

OK.

> > (2) Add readme.txt about the different defconfigs so we understand
> >     which platform they target, and where it can be found, if freely
> >     available.  
> 
> We'll do that.

Good.

> > (3) Perhaps make it possible to build the ARC-specific qemu, so that we
> >     can out of the box have a qemu that we can use to boot test one ARC
> >     platform. Then we can enable that in our Gitlab CI  
> 
> Well, QEMU for ARC is easily doable. I guess it's more of a question on how to
> integrate it with Buildroot's GitLab flow, any references to docs on the matter
> (sorry if asking something simple, but while I have your attention, possibly you
> may point me at something immediately)?

We probably need to simply tweak the existing Qemu package. Not a
priority, but would be nice.

Something more important: fix the broken snps_arc700_axs101_defconfig.
You're normally receiving e-mails about this. If not, let me know,
because it means there is an issue in the notification machinery.

See:

 https://gitlab.com/buildroot.org/buildroot/-/jobs/4795673779
 https://bugs.busybox.net/show_bug.cgi?id=15446

Thanks a lot!

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com