> mcrxr does not exist anymore. It is not implemented in any IBM non-embedded > CPU since POWER4. PA6T does not have it either. In some versions of the > 2.0x ISA it does exist, but only in the optional "embedded" category.
Yes, it exists in all (public) versions of the unified 2.0x ISA. > Linux emulates mcrxr, but that is very slow. You could use mfxer, but > that is a slow instruction as well (it is microcoded). So there is no efficient way of accessing the OV flag in recent non-embedded CPUs (except for the new mcrxrx instruction in the 3.0 version)? > That may work better. It also may be better if you expose the OV bit > as a separate reg (just like we have CA), instead of putting two machine > insns in each template. Yes, although CA can be seen as behaving like a register to some extent, but OV far less so IMO. -- Eric Botcazou
