> > Why does that make a difference? I suppose that I don't know the > > details of what mode things like the context switch routines run in. > > From looking at the code, it would seem that it's the 32-bit mode in > > the 32-bit kernel. > > What anwers your question. N32 will need e.g. to save&restore 64bit > wide registers, does syscalls with 64bit registers and so on. > A 32bit kernel doesn't know how to handle this.
That doesn't answer my question; you do not make it clear if it is impossible for a 32-bit kernel to save the contents of a 64-bit register, or if it's merely missing code. Since I've only dealt with mips64, I don't know what limitations that the mips32 architecture has. Looking at my mips64 ISA, it says that "SD" is an example of an instruction that is not available in mips32, so that means it's impossible for a mips32 kernel to do n32. greg
