Crossbuilding for different platform with pkgsrc

nettester

Hi,

i am currently playing around with netbsd a bit and i was very positively impressed by being able to crossbuild kernel and userland on a linux host. Now i wanted to see if it was possible to do the same for binary packages but i am hitting a wall and i am not really sure if i am doing something wrong or if it's just not possible (yet?).

At least the pkgsrc readme on crossbuilding seems to suggest that it's only supported on netbsd across different architectures and setting USE_CROSS_COMPILE=yes / CROSS_TOOLDIR=[tooldir-path] / CROSS_DESTDIR=[destdir-path] doesn't seem to work. The directory pointed to by CROSS_TOOLDIR contains the toolchain generated by build.sh during the build of the system, so there should be a usable toolchain available but from what i understand it isn't even used during the package build process. It seems to insist on building for linux and the architecture chosen by MACHINE_ARCH.

I managed to (somewhat) force it to use the cross toolchain by setting MACHINE_GNU_PLATFORM=i486--netbsdelf / NATIVE_MACHINE_GNU_PLATFORM=x86_64--netbsd and adding the the [tooldir]/bin directory to the path before running bmake but i doubt that's really the appropriate solution and it's not producing any usable results anyways. While it sometimes seems to work the linker regularly gets stuck trying link binaries which should come out native to netbsd against libraries/objects from the host system, which obviously fails.

Anyways, at this point i am out of ideas. Any pointers or information on if what i am trying to do is even possible would be greatly appreciated. I really don't want to run qemu just for building packages but i've spend so much time on trying to get this working already that unless someone has some kind of hint or suggestion i'll probably give up and bite the bullet. It would be quite awesome if i wouldn't have to though.

Thanks for your time and sorry for my weird English!

Edit: If my post is better suited for the pkgsrc section i'd appreciate it being moved.

nettester If my post is better suited for the pkgsrc section i'd appreciate it being moved.

Done

nettester Soon, might be possible. Saw this today and remembered your question. Soon ...

JuvenalUrbino

I regret having not seen this thread before, so sorry if nobody replied. I've never looked into cross-OS complication (just did cross x86->evbarm), and I wonder if it's feasible at all. The HOWTO-use-crosscompile doesn't mention it. This is topic would make an interesting thread on the pkgsrc-users mailing list.

nettester

JuvenalUrbino

Crossbuilding the OS itself works flawlessly (well at least in my case it does - Linux amd64 host with i386 NetBSD target). Actually it's very, very simple. In the most basic case passing -m i386 -U to build.sh is pretty much all that's needed.

The only thing that seems a little weird is build.sh's tendency to rebuild tools even if a working toolchain already exists and it's location is provided by the -T option. I think as long as -u is passed it'll actually use the existing toolchain but i am not entirely sure. Since i am building userland/kernel in different steps and i usually want to rebuild everything related to the current step using -u is a little awkward but then i am not rebuilding that often for it to make that much of a difference (avoiding to rebuild gcc all the time is obviously tempting though).

Considering pkgsrc i tend to agree with you. From the wording used by the HOWTO it seems like crossbuilding is only supported if host and target are both NetBSD systems running different architectures. I'd think in theory it would be feasable accross different OSes though. If the NetBSD kernel/userland can do it (both systems seem to basically build most of their functionality upon BSD make after all) the only obvious problem i see seem to be system supplied libraries/headers, which would either have to be provided for pkgsrc to build against or avoided by building replacements through pkgsrc itself.

I also agree that it's quite an interesting topic (thanks for the mailing list pointer by the way!) but i fear i don't have the time to do much investigating/hacking right now. For now i'll probably have to stick to automated VM builds, even if firing up VMs and interacting through scripted ssh commands is not exactly elegant. I've wanted to better familiarize myself with BSD make (it's a beast! - documentation seems rather scarce but from my impression there isn't much that comes close to it) for a long time though, so i might very well get back to it at some point.

JuvenalUrbino

nettester If the NetBSD kernel/userland can do it (both systems seem to basically build most of their functionality upon BSD make after all) the only obvious problem i see seem to be system supplied libraries/headers, which would either have to be provided for pkgsrc to build against or avoided by building replacements through pkgsrc itself.

Concerning NetBSD --> Linux cross-compilation, wonder if this could be handled by pkg_comp running in a Linux sandbox (automated chroot inside /emul with compat_linux enabled and a suitable set of suse-* packages installed).

nettester

JuvenalUrbino I think you might be on to something there. Thinking about it chroots could actually be a good approach even with other host/target combinations. Of course it gets a bit more tricky without kernel compatibility but from my (limited) understanding of pkgsrc's inner workings it seems that simply detecting if the current build is a "tool" rather than a "real" package and switching between toolchains accordingly could be enough to make cross builds work.