Ada and x86_64

[Robert Dewar]

The documentation you need for porting the system dependent files is found
in the specs of the files involved, but it is important to be aware that
creating a new runtime for a new port is a non-trivial task that certainly
requires a good knowledge of Ada and a good familiarity with the structure
of the GNAT runtime (it's all documented, but there is a lot of it). There
is no quick "port GNAT in half an hour" procedure, it just does not exist.