> Hi, > > is it possible to build a kernel that does not use the FPU part of CPU > at all? I have tried to enable all the FPU_EMULATION config options of > 2.4.27 but the kernel still uses FPU instructions... That would be fsave and frestore, in order to save/restore FPU context on behalf of user processes on context switching only. The kernel does not save/restore FPU state on system calls, and does not use the FPU internally. You can perhaps comment out these instructions, but that would certainly mess up kernel FPU emulation as well. A kernel designed for FPU emulation _only_ would have to replace the fsave/frestore with equivalent instructions to save the emulator 'registers' on the stack. Kernel FPU emulation just means there is a F-line trap handler available. That trap should also work on context switching, unless I'm mistaken. > Has the 68881 emulation been tested for real in linux? Does it work > properly? Yep, it's been tested as far as I know, and it should at least work as far as kernel FPU state save/restore is concerned. I think FPU emulation was somewhat incomplete at that time (missing transcendental functions) though. Roman Zippel should really answer this one, though :-) Michael - To unsubscribe from this list: send the line "unsubscribe linux-m68k" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
