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Re: [Qemu-devel] [PATCH] target-arm: support for ARM1176JZ-s cores
From: |
Jamie Iles |
Subject: |
Re: [Qemu-devel] [PATCH] target-arm: support for ARM1176JZ-s cores |
Date: |
Wed, 22 Jun 2011 16:45:55 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Wed, Jun 22, 2011 at 10:40:12AM +0100, Peter Maydell wrote:
> On 22 June 2011 00:42, Jamie Iles <address@hidden> wrote:
> > On 21 June 2011 23:13, Peter Maydell <address@hidden> 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
- [Qemu-devel] [PATCH] target-arm: support for ARM1176JZ-s cores, Jamie Iles, 2011/06/21
- Re: [Qemu-devel] [PATCH] target-arm: support for ARM1176JZ-s cores, Peter Maydell, 2011/06/21
- Re: [Qemu-devel] [PATCH] target-arm: support for ARM1176JZ-s cores, Jamie Iles, 2011/06/21
- Re: [Qemu-devel] [PATCH] target-arm: support for ARM1176JZ-s cores, Peter Maydell, 2011/06/21
- Re: [Qemu-devel] [PATCH] target-arm: support for ARM1176JZ-s cores, Jamie Iles, 2011/06/21
- Re: [Qemu-devel] [PATCH] target-arm: support for ARM1176JZ-s cores, Peter Maydell, 2011/06/22
- Re: [Qemu-devel] [PATCH] target-arm: support for ARM1176JZ-s cores,
Jamie Iles <=
- Re: [Qemu-devel] [PATCH] target-arm: support for ARM1176JZ-s cores, Peter Maydell, 2011/06/22
- Re: [Qemu-devel] [PATCH] target-arm: support for ARM1176JZ-s cores, Jamie Iles, 2011/06/22
- Re: [Qemu-devel] [PATCH] target-arm: support for ARM1176JZ-s cores, Peter Maydell, 2011/06/22