On Wed, 7 Feb 2001, Florian Lohoff wrote: > The problem with not compiling in the FPU Emulator at all means some > of your FPU instructions (even on FPU hardware) will fail as on some > specific operators the hardware decides to handle it in software. So > usually you would need an FPU Emulator even on FPU enabled CPUs. I mean a full emulator. I know that for simplicity certain actions required by the IEEE spec are handled in software (Alpha does it as well). These bits have to be always included, of course. I would like to save wasted bits for hardware that always has an FPU, though. > This isnt true if you decide to compile your complete userland with > fpu emulation. I'm not sure if that approach has any advantages when using an operating system such as Linux. It might certainly be beneficial for firmware or similar dedicated software. > I dont know if this is a generic way to go - I saw complete "full-stops" > on an R3912 using the ctc/cfc instructions - I'll try the autodection > when i come home. We might work around pathological cases as usual -- such a behaviour should count as a bug (I hope IDT did have a clue here -- is there any original MIPS statement on how to handle FPU presence detection?). You might use the i386 setup code for a reference as a large mine of bug workarounds. Maciej -- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +
