mitigating non-determinism

[John Gilmore]

"Bernhard M. Wiedemann via rb-general" wrote:
> ASLR:
> Influences from address-space-layout-randomization(ASLR) can be avoided 
> with setarch -R COMMAND or globally with echo 0 > 
> /proc/sys/kernel/randomize_va_space . This also helps with some cases of 
> uninitialized memory.

Anytime we find programs using uninitialized memory, we should debug
them, not change the build environment to make them seem OK.

(I found a couple of bugs like this in the GNU assembler back in the
1990s, that produced different instruction sequences based on reading an
uninitialized variable.  This hadn't been noticed before testing
reproducibility, because all the sequences were valid instructions.  I
think the bug was in picking long or short offsets, perhaps in jump
instructions.)

	John