I forgot to mention that I was able to verify that the floating point emulator *works*. I examined the result of a floating point division in memory and it was valid. So I guess it is the libc I am using. Like I said, could it be that it was compiled with -msoft-float?
I'm also not sure I can draw conclusions from the following fact, but I disassembled the libc used on the board, and found no floating point instructions. I did the same with a libc on a powerpc 604 I have here, and did find floating point instructions. Regards, Alban Alban Wood wrote: > 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 > > > ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
