gcj-related bof at javaone

Mon Jun 12 10:29:00 GMT 2000

Per Bothner wrote:
> I noticed on gcj-related bof at javaone:
> "Using Java Technology as an Operating System Language"

Pekka Nikander has made this work for the Lego RCX available at
<uri: http://www.tcm.hut.fi/~pnr/rcx/ >.
It is based on gcj from CVS (not 2.95.x). I believe he started with
libgcj but rewrote most of java.lang and java.lang.reflect to run in as
little as 16kb (the RCX has only 28kb usable address space). The
library currently supports preemptive threads and exception handling,
but no GC and no floating point.
Pekka's goal was to write a complete embedded OS using only Java and
assembly. He had to use some C++ (via CNI) since there are idioms in C
that cannot be expressed in Java, like using a struct to map a range of
ports (the RCX has memory-mapped I/O). Pekka was able in some cases to
use "static volatile" Java class variables directly mapped to ports
however.
Though I don't work on embedded targets, this is cool stuff indeed...
--
Jeff Sturm
jsturm@sigma6.com