With the last CVS tree of kaffe and the help of Edouard Parmelan, fearless kaffe developer, everything works.
Ultra-Short-HOWTO: 1) Get FFI from http://sourceware.cygnus.com/libffi/ (it does not seem to be in any Debian package) and install it (./configure; make; sudo make install) 2) Get the latest CVS of kaffe <http://www.kaffe.org/CVS.html> 3) Configure kaffe: ./configure --with-libffi 4) make; sudo make install It just works (tested with the free XSL engine XT, a huge beast, and some small Java programs). There are still bugs, of course, we'll see later. (Freenet crashes, for instance, because of a problem with BigInteger).