Luajit on ppc64el

[bugproxy]

We would need to have patches to enable luajit to build and run on ppc64el.
Those patches exists.
I've opened a bug on debian and ubuntu to have them integrated in the packaging for the time being :
* https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=814255
* https://bugs.launchpad.net/ubuntu/+source/luajit/+bug/1543649

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1544649/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[Steve Langasek (vorlon)]

It is not out of the question for Ubuntu to take these patches in advance of Debian and/or upstream, but at the moment I don't believe we're able to commit to delivering such a fix for this Ubuntu universe package in the 16.04 release.

[Breno Leitão (breno-leitao)]

Debian included ppc64el support on luajit version 2.1.0~beta2+dfsg-3. It is still on experimental archive right now.

Is it possible to cherry pick the ppc64el patch from this version?

[Steve Langasek (vorlon)]

The ppc64el patch in luajit 2.1.0~beta2+dfsg-3 in Debian experimental does not apply cleanly to luajit 2.0.4+dfsg-1. Is the debdiff in https://bugs.debian.org/814255 still applicable, and is it complete?

I notice that the patch from https://bugs.debian.org/814255 touches some code that would be common to ppc4el and powerpc. How has this been validated to be correct on powerpc? (This is less important for 17.04 than for any possible future SRU.)

[Breno Leitão (breno-leitao)]

Hi Steve,

Correct, the ppc64el patches in 2.1 does not apply on version 2.0 due to a missing layer called LJ_GC64.

In fact, luajit version 2.0 only supports 32 bits architectures, and has an exception for amd64, that is heavily based on the MAP_32BIT mmap flag. The MAP_32BIT flag is only supported in the x86 world.

In luajit version 2.1 there is a more broad support for 64 bits architecture.

That said, I understand that it would be very hard (and risky) to backport ppc64el support into luajit version 2.0. Moving to version 2.1 would be a better idea, IMO.

Other than that, we tested this patch on powerpc and it works fine also.

[Breno Leitão (breno-leitao)]

I talked to Enrico and Ondřej (Luajit maintainers), and they are going to move luajit 2.1.0~beta2 to unstable as soon as stretch is released.