On Wed, 1 Feb 2006, Daniel Jacobowitz wrote: > All of this code is flat-out wrong, as far as I'm concerned. I have a > project underway which will fix it, as a nice side effect. Great!. > GDB is trying to do something confusing, but admirable, here. When > you're running on a 64-bit system the full 64 bits are always there: > even if the binary only uses half of them (is this true in Linux? I > don't remember if the relevant control bits get fudged, it's been a > while; it's definitely true on some other systems). Thus it's possible > for a bogus instruction to corrupt the top half of a register, leading > to otherwise inexplicable problems. Well, cp0.status.ux is always set with a 64-bit kernel. It is not with a 32-bit one. A binary marked as o32/MIPS-III will work with either as long as 64-bit operations are not used. For implementations that provide the cp0.status.xx bit, it is always set so that at least 32-bit MIPS-IV instructions work. Maciej
