devkitPro

Would have been a bit better if you'd posted some details here - I think I still have a login for gp32x but I'm trying to avoid the distractions of reading and responding to posts in the many forums where devkitPro toolchain users lurk.

The basic problem with those EABI SDL++ libraries is the hacking of libc which I believe actually predates devkitARM - it's a particularly nasty way to do what needs done. The ideal situation would be for the extra functions to be extracted into a separate library & use made of the newlib hooks provided by devkitARM instead. Once that's done it should just be a simple matter of rebuilding the rest of the libraries with devkitARM.

It's not a particularly difficult job but it might be a bit on the time consuming side and needs a bit of thought. On DS, GBA and Wii we're using libfat for file access which hooks into newlib through our pseudo device system - it might be best to use that for gp32 as well but it does mean linking all applications with libfat if this needs initialised during startup.

Something I'm not really clear on with these libraries. Is this an alternative to libmirko and the official gp32sdk or is it intended to work with either of them?

No, this has very little chance of working. What you're trying to do here is use some unknown and inappropriately patched newlib built with some unknown version of gcc.

The only sensible way to approach this is to extract the gp32 specific parts, separate them into a new library, add the appropriate glue code for devkitARM and rebuild everything with the latest devkitARM. Anything else is just going to fail in various interesting ways.