On Wed, Jun 22, 2011 at 10:40:12AM +0100, Peter Maydell wrote: > On 22 June 2011 00:42, Jamie Iles <ja...@jamieiles.com> wrote: > > On 21 June 2011 23:13, Peter Maydell <peter.mayd...@linaro.org> wrote: > >> Ah yes, sorry, I misread the TRM there. So it does have those, it's > >> just the SEV/WFI/WFE it is missing. I guess we'll want an > >> ARM_FEATURE_VAPA too. > > > > Could we perhaps infer and detect some of these features? For example, > > my reading of the ARM ARM says that the VA<->PA translation registers > > exist for >v7 or v6k if the security extensions exist. We can detect > > the security extensions from the cpuid registers so we could > > automatically set that feature. > > I thought about that, but there are a couple of reasons I'd rather > not detect things from the cpuid/feature registers: > * older cores don't have them, so you need to cope without them anyway > * there's a tension between "emulate the same feature regs as the > h/w" and "emulate feature regs matching what we implement" -- some > guest OSes will actually refuse to boot unless they get exact matches > on the feature reg values... > (At the moment we tend to the former, so we probably advertise the > security extensions even though we don't implement them, for instance) > * at the moment the feature regs are just random hex values in helper.c; > if we wanted to drive things from them we'd need to set up a lot of > enumerations and constants anyway in order to have something maintainable > > Inferring ARM_FEATURE_foo flags from other ARM_FEATURE_foo flags is fine, > though. > > Mostly what I'd like is for the actual code implementing things to > be gated on a fairly fine-grained set of flags, so that we can confine > the "what does this core have? what things imply what other things?" > code to a single place where it's easy to tweak if we get it wrong.
OK, I don't think I can object to that! I'll submit a patch to fix up the v7 VMSA ap/remap dependency to be v6K rather than v7. Given that, do you have any objection to adding 1167 as a v6K? I'm happy to help with/test some of the feature cleanup. Jamie
