Re: Staging branch [substitute availability]

["Ludovic Courtès" <ludo@gnu.org>]

Mathieu Othacehe <othacehe@gnu.org> skribis:

> Since the introduction of the "wip-offload" branch on Cuirass, the
> situation has much improved. The workers are constantly building. For
> now we are building three specifications:
>
> * guix-modular-master
> * guix-master
> * staging

Yay!

> for x86_64, i686 and aarch64. If you look at the "Pending builds" chart
> here[1], you will see that the CI is barely catching up. That's because
> the "aarch64" emulated builds are incredibly slow, and monopolizing all
> the build resources.
>
> I deliberately chose to put armhf aside until I have a clearer view of
> the situation.
>
> Now, how to move on?
>
> First, I still need to connect the four overdrives machine to the new
> Cuirass remote building mechanism, and I would need some help for that
> (asked on guix-sysadmins). But, I'm not sure it will much improve the
> situation.

Oh sorry, I still haven’t caught up from vacation but I’ll take a look
if nobody beats me at it.

> Longer term, we need to figure out a better solution. It's now
> obvious that we do not have the computation power to build all our
> branches for 5 different architectures, relying heavily on emulation for
> armhf and aarch64. Anyone knows how Nix deals with that?

I’m not sure, but I know they rent storage and processing power from a
big transnational company, and that may well include AArch64.

Note that we disabled emulated builds and ARMv7 builds on AArch64 (!)
when Danny discovered the _FILE_OFFSET_BITS issue, which makes things
much worse.

With the x86_64 machines we have in Berlin, using emulated builds, even
if they’re slow, could potentially help noticeably.

At this point the biggest issue is ARMv7 because we have too little
actual hardware.

> I guess that other major distributions provide only cross-compiled
> packages for those architectures, but I don't think it's an option for
> us, Ludo?

Cross-compiled derivations are different derivations, so no, it’s not an
option.

If people know what hardware to get, and if we can find people to host
it, we have enough funds to buy it.  On IRC yesterday Leo mentioned a
good-looking AArch64 board:

  https://shop.solid-run.com/product/SRLX216S00D00GE064H07CH/

For ARMv7, there are probably several known-good options like those by
Olimex, BeagleBoard (I think?) and the likes.

For any such candidate, we need to (1) check it can be used with free
software only, (2) check things like provided storage space, whether a
case is available, etc., and (3) plan for purchase and hosting.
Volunteers needed!

Thanks,
Ludo’.