Possible to compile tree on a different OS?

[Ed Maste]

On Tue, 16 Jun 2020 at 01:27, mayuresh at kathe.in <mayuresh at kathe.in> wrote:
>
> The NetBSD folks have mechanisms in place to allow compiling (including cross-compiling) their entire (or partial) source tree under a different operating system. Eg. I can download and compile the NetBSD source tree under a Ubuntu system using GNU build tools.
>
> Does FreeBSD have such facilities in place too?

Unfortunately we don't have anything "out of the box" for building on
non-FreeBSD hosts yet, but there is significant work in progress to
make it possible. The CHERI research project at Cambridge has build
infrastructure for all of the components they're using (modified
research versions of QEMU, Clang/LLVM, and FreeBSD) that builds on
FreeBSD 10+, Ubuntu 16.04+, OpenSUSE, and macOS.

You can find more information about that work here:
https://github.com/CTSRD-CHERI/cheribuild
https://wiki.freebsd.org/BuildingOnNonFreeBSD