Hello Rich,
Ideally I'd like to cross compile on my x86_64 desktop. This I do by creating docker images of the target environment and using that for the x-compile and linking. In this case, as the app is quite small, I could do the compile using a re-mastered images of piCore on the RPi itself (I guess, I haven't tried it yet).
I probably should explain: I develop in Rust, not C. Rust has good support for arm-unknown-linux-gnueabi and I have already cross compiled for this architecture. The real problem comes when linking to libraries; I've found that if I don't use the exact version that's in the target environment then weird stuff can, and will, happen.
So I need the libraries from the extension packages and their header files for the foreign function interfaces. I thought that if a development environment already existed for piCore similar to OpenWRT, then that would save me a lot of time, cheers.
--
Geoff