On Thu, 2016-11-10 at 21:36 +1100, Michael Ellerman wrote: > Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx> writes: > > > > > On Tue, 2016-11-08 at 19:21 +1100, Michael Ellerman wrote: > > > > > > Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx> writes: > > > > > > > > > > > > > > > ISA 3.00 adds the logical PVR value 0x0f000005, so add a > > > > definition > > > > for > > > > this. > > > > > > > > Define PCR_ARCH_207 to reflect ISA 2.07 compatibility mode in > > > > the > > > > processor > > > > compatibility register (PCR). Also define a dummy ISA 3.00 > > > > compatibility > > > > mode PCR_ARCH_300 to be used in the next patch to help with > > > > determining the > > > > PCR value. > > > What's "dummy" about the PCR value? > > > > Then next patch needs some PCR bit to specify that we want to > > emulate > > v3.00 and/or that the host can emulate v3.00 to follow the pattern > > used > > to determine that the host is capable of emulating the given compat > > level and for determining which PCR bits to set. But no such bit is > > defined for V3.00 compat mode yet so a "dummy" one is used to > > represent > > this even though it's never defined in the ISA. > > > > > > > > > AFAICS that value is reserved in the ISA. > > > > Yes it is a reserved bit in the PCR register but it will never > > actually > > be set, it will always be cleared by "host_pcr_bit - > > guest_pcr_bit;" > > > > > > > > > > > Are we assuming/hoping that ISA 4.0 will use 0x10 to mean ISA 3.0 > > > ? > > > > Basically yes, and although I know nothing's given, it would follow > > the > > current pattern for whatever the next ISA version is to use 0x10 to > > mean V3.00 compat mode. Otherwise this will need to be updated at > > some > > point when that's released... In fact if the compat bits are no > > longer > > sequential this will need rewriting. > > OK thanks. > > Please send a v4 with that detail in a comment and a better > explanation > in the change log. > > I think a block comment before the #define would be best, ie. > something Will do and send a V4 > like: > > #define PCR_ARCH_207 0x8 /* Architecture 2.07 > */ > > /* > * All that helpful detail from above ... > */ > #define PCR_ARCH_300 0x10 > > > We should also ask if we can get 0x10 reserved in the ISA to mean > 3.00. Probably a good idea, might ask you about the process for this on Monday... > > cheers -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
