Subject: Re: bug#49218: texlive-latex-base fails to build: "missing engine: luajithbtex"

From: Chris Marusich <[email-masked]>
Date: Tue, 06 Jul 2021 21:08:30 -0700

Hi,

I've committed the patch as 68b0e0d511c2873603636e9f783ff59aac4b7612 on
core-updates.  I'm closing this bug report.

Chris Marusich <[email-masked]> writes:

> - Will LuaJIT ever support the powerpc64le architecture?  Until it does,
>   I guess we can't use LuaJIT on powerpc64le at all, not just for
>   TeX-related stuff.

See: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=49220

In short, it does not seem like upstream support for powerpc64le is
forthcoming in the near future.  But maybe that will change with time.

> - Is it correct to add "mfluajit" to the disabled-formats list, like I
>   do in my patch?  It sounds like "mfluajit" is a related to "metafont",
>   but I don't yet really understand what that means.  Is it an engine
>   like luajit?  Is it correct to include mfluajit in the list of formats
>   to disable in fmtutil.cnf when running fmtutil-sys?  I am totally
>   unfamiliar with these tools, so I have no idea.  Perhaps it makes no
>   sense to include mfluajit here, even if maybe it is benign to do so.
>   If any TeX wizards out there can clarify this for me, I'd be happy to
>   adjust the patch as needed.

FYI, I found this information about formats and engines:

https://www.tug.org/levels.html

According to that document, "engines" are "executable binaries which
implement different TeX variants", and "formats" are "the TeX-based
languages in which one actually writes documents".  The config file
contains lines like this:

  # from lollipop:
  lollipop tex - lollipop.ini
  #
  # from luatex:
  luatex luatex language.def,language.dat.lua luatex.ini
  dviluatex luatex language.def,language.dat.lua dviluatex.ini
  luajittex luajittex language.def,language.dat.lua luatex.ini
  #
  # from metafont:
  mf mf-nowin - -translate-file=cp227.tcx mf.ini

It looks to me like it's fine to include "mfluajit" in the
disabled-formats list.  Clearly, some metafont "formats" and "engines"
are included in this config file already.  That said, adding "mfluajit"
to the list does nothing right now, since the config file doesn't
actually contain any lines beginning with the word "mfluajit", anyway.
And in any case, if "mfluajit" ever does get added to the config file
somehow, then surely we would want to disable it for powerpc64le-linux,
since LuaJIT is not currently supported on that platform.  Therefore, I
think it's correct to include "mfluajit" in the disabled-formats list.

-- 
Chris