Worked a little bit more on the ABIv1 x86_64 started long time before. Found some errors and got the FP-IDE to work and some simple example sources. But LCL and fpGUI still do not work. The main reason for that are the changes between ABIv1/ABIv0 and some inconsistencies of 32bit/64bit types.
Bad thing, changes are not denoted in the C-header files for AROS, so it’s a very annoying comparing work done by hand to find if there are differences. Differences in Library offsets for functions in the most important libs are done and exec structures are also fixed.