Hi Helmut, On Sun, Dec 10, 2023 at 09:01PM, Helmut Grohne wrote: > First and foremost, ghc now actively refuses being cross build with an > $(error ...). Would you mind weakening this to a $(warning ...)? While > that you don't want to support cross building of ghc, would you mind > others (like me) supporting it? Yes, it would still fail, but then > https://crossqa.debian.net/src/ghc could show a more useful reason for > that failure.
The reason I have this as an $(error ...) is because the new Hadrian build system doesn't support cross-compiling GHC [1]. This is not a limitation of our Debianization (i.e., it's not that we refuse to cross-build GHC, we *cannot* cross-build GHC), this is upstream limitation. Given that, I believe $(error ...) is more appropriate here than $(warning ...). [1] https://gitlab.haskell.org/ghc/ghc/-/issues/23975 > Then when you get past the $(error ...), stage1 tools are not found. In > a cross build, ghc prefixes these with the host gnu triplet. A bit of > renaming is required to make this work. (patch attached) The resulting stage1 tools are a cross-compiler, not the final cross-compiled binaries (this is why they are prefixed with the host gnu triplet). I am not sure how we will handle this, I am waiting to see on what upstream will do to support cross-building GHC. For now, I believe applying the attached patch doesn't help. > And then we run into: > > On Tue, Oct 09, 2018 at 03:24:41PM +0200, John Paul Adrian Glaubitz wrote: > > This change to the debian/rules file helps to get a bit further: > > > > --- debian/rules.orig 2018-09-26 11:08:46.000000000 +0200 > > +++ debian/rules 2018-10-09 15:22:43.080942145 +0200 > > @@ -126,6 +126,7 @@ > > echo 'V=1' >> mk/build.mk > > dh_auto_configure -- \ > > $(EXTRA_CONFIGURE_FLAGS) \ > > + --host=$(DEB_BUILD_GNU_TYPE) \ > > --with-system-libffi --libdir=/usr/lib > > > > override_dh_auto_build: > > > > But it will still fail with: > > I think this is wrong. The current ghc packaging includes this flag, but > ghc uses the same terminology as Debian, so when we say > --host=$(DEB_BUILD_GNU_TYPE) we ask it to produce a cross compiler, but > we really wanted a cross built ghc. One of the issues referenced from > the earlier $(error ...) also hints that this value is wrong for --host: > https://gitlab.haskell.org/ghc/ghc/-/issues/22006 Unless you have strong > reasons for why that should be correct, I suggest that we change it to > --host=$(DEB_HOST_GNU_TYPE). (not included in patch) GHC does *not* use the same terminology as Debian. GHC requires that HOST and BUILD are the same. You can read more about this here [2], though keep in mind this document is severely outdated with the Hadrian build system. [2] https://gitlab.haskell.org/ghc/ghc/-/wikis/building/cross-compiling#terminology-and-background > So this is where we are. I think we can make progress here if you want > to support this work. I'm also a big fan of actionable bug reports and > in having a patch, this bug becomes actionable. Given that you (ghc > maintainers) are evidently not interested in doing the work here, I also > suggest that you close this bug when applying the patch and letting > cross users file new bugs with new patches. Let me know what you think > about this. I believe we need to work with upstream to add support for cross-compiling GHC to the new Hadrian build system. As explained here [3], this is currently not possible. I tested everything I could think of, but I don't see how we can move forward without reworking how the Hadrian build system works. Upstream has started working on this, but it's moving slowly [4]. In summary, as a result of the switch to the Hadrian build system, we are now unable to cross-compile GHC. Since this issue now has all the latest context, I propose we keep it open and work here on cross-building GHC. [3] https://gitlab.haskell.org/ghc/ghc/-/issues/23975#note_526546 [4] https://gitlab.haskell.org/ghc/ghc/-/issues/23975#note_530201 Thanks, -- Ilias
