good news and bad news on floating-point problems
The good news first:
When patched with the DEC-supplied patches, kernel 2.0.34 and when the
CONFIG_MATHEMU=y switch is set in linux/.config, the kernel 2.1.208
both produce the desired result for a floating divide by zero.
Namely, with the -mieee switch set, a floating divide by zero will
show as "Inf." when printed. Further, the same test code when
compiled with the -fpe1 switch on DEC-Unix f77, will also produce the
correct result. Even further, with the correct dynamic libraries
installed, the -non_shared switch is not necessary.
The bad news:
My large, production, legacy code when compiled with the same switches
on either side (Linux or DEC-Unix) core-dumps on floating-point
exceptions. The same code runs correctly on DEC-Unix with -fpe1
switch enabled. What is really odd is that at one time, with "some"
kernels, this did not occur and the code ran correctly (both "g77
-mieee" compiled or "f77 -fpe1" compiled).
I guess there are listed 5 floating exceptions that can occur with
divide by zero being one of them. Apparently the -mieee and/or the
MATHEMU does not catch all of the possibilities.
So close yet so far away...
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