On Wed, 2018-01-17 at 20:51 +1100, Paul Mackerras wrote: > + > + /* > + * POWER9 chips before version 2.02 can't have some threads in > + * HPT mode and some in radix mode on the same core. > + */ > + if (cpu_has_feature(CPU_FTR_ARCH_300)) { > + unsigned int pvr = mfspr(SPRN_PVR); > + if ((pvr >> 16) == PVR_POWER9 && (pvr & 0xfff) < 0x202) > + no_mixing_hpt_and_radix = true; > + } > + > return r; > } You need to check that it's a Nimbus using the top nimble of the bottom 16 bits of PVR. For Cumulus, the fixes are either in 1.0 or 1.1 (to check). Cheers, Ben.