gcj and UDP datagrams under freebsd

Fri Apr 5 16:49:00 GMT 2002

Hi Mark,
[...]
> % ./snd guns
> assertion "!(addr & FLAGS)" failed: file
> "/home/mallman/GCC/libjava/java/lang/natObject.cc", line 772
> Bus error (core dumped) 

> This is on a freebsd 4.4 machine.

A few comments. FYI, you will experience random GC deadlocks on
FreeBSD 4.4 and all previous releases (unless you disable threads
entirely when bootstrapping gcc). Please upgrade to
FreeBSD-4.5-RELEASE or FreeBSD-4.5-STABLE to use gcj.
However, that is not your problem here.
> I tried to same thing on my redhat 6.2 laptop (same version of gcc
> that I grabbed from CVS a couple days ago) and it all worked as I
> had envisioned. (The difference is the I don't have to use
> "-pthread" when compiling on the linux box.)

> Anyone have a guess about what is going on? Any help would be
> appreciated.

Yes, dear lord, this code is doing something *very* nasty with the low
bits of pointers. Luckily, it had this nice assert() instead of
crashing wildly. ;-)
Compiling your code and running it, I see the same crash:
#2 0x2830b105 in _Jv_MonitorEnter (obj=0x285a8b8c)
with FLAGS == 7 and addr == obj, assert(!(addr & FLAGS));
Yup, that doesn't fly on this platform unless some care is used for
all memory allocations. Until we figure out how to fully address the
situation, you could disable the hash synchronization code. Drop this
line:
enable_hash_synchronization_default=no
into the *-*-freebsd* section of the second case in
libjava/configure.host and completely rebuild libjava (merely
rerunning make after a reconfigure doesn't work in this case).
Since I doubt I will be able to fix this before 3.1 release, I think
this should be disabled on the branch. Funny that there were zero
test cases to catch it. I will try to work up such a case.
Regards,
Loren