mpc8xx fpu emu

[Alban Wood]

hello,

Regarding my problem, I searched the list archives and did found some mpu
emul related posts but they were not exactly like my case.

Basically, I have an RPX Lite-M board. The mpc850 does not have an fpu,
but I have a need for non-intensive fpu operations. I don't want to
compile applications and librairies with -msoft-float - for my needs the
fpu emulator is really the way to go.

The board successfully boots a slightly modified linux 2.4.9. I've
compiled the kernel with and without math emulation.

I also compiled a very simple application that does a floating point
division and prints it. I explicitly specified -msoft-hard. (same with the
kernel btw), checked out the resulting assembly and did in fact find an
fdiv instruction.

Without the emulation, executing the program results in a floating point
exception. This is normal.

With the math emu kernel, the exception is caught and seemingly handled as
it should. However, a printf of a float results in "nan" (not a number).

If I invoke the printf binary (printf "%f\n" 43.34343) it is able to print
a float.

I didn't compile my own toolchain. I switch between the binary
distributions I got from www.qslinux.org and timesys. I'm not sure this is
a good idea.

Any ideas as to what could be wrong? Could it be that the libs in the root
filesystem I'm using for the board were compiled with -msoft-float,  and
that as a result printf cannot properly output a float? (even though it's
been properly handled by the fpu emulator?)


Thank you,


Alban


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