Hi Paul, > > FAOD <cpu-feature-overrides.h> is not a hack, but an optimisation measure > > so that features known to be hardwired for a given machine/CPU do not have > > to be dynamically queried every time referred. In some cases that results > > in large portions of code being optimised away by the compiler as well. > > Fair enough. Bloat-o-meter reports about ~100 KiB saved when that file is > present. But we can't use it in a generic kernel, unfortunately. Well, run-time patching might be an alternative to get the best of both worlds, but someone would have to reimplement our feature selection system to use it. > > The hardcoded value for a feature defined in <cpu-feature-overrides.h> > > always has to be the same as one in the corresponding bit of the `options' > > member of `struct cpuinfo_mips', in this case MIPS_CPU_TLBINV. > > In theory yes, in practice the CPU detection code is lagging behind... I wasn't aware of that. In that case it has been a design abuse which has been missed by the maintainer when accepting patches. It used to be the case that run-time detection was accurate and overrides were rather lazily added. Also I note Ingenic must have had a CPU erratum if our `decode_configs' doesn't just work, as the interpretation of CP0.Config[5:0] registers has been architectural and mandatory, and that for a reason. It's only legacy MIPS I-IV processors that should require special attention here. Maciej
