Re: [Qemu-devel] [PATCH target-arm v1 1/9] target-arm: Prepare support for Cortex-R5

[Peter Maydell]

On 2 June 2015 at 10:25, Peter Crosthwaite <address@hidden> wrote:
> On Mon, Jun 1, 2015 at 11:44 AM, Peter Maydell <address@hidden> wrote:
>>> +static void cortex_r5_initfn(Object *obj)
>>> +{
>>> +    ARMCPU *cpu = ARM_CPU(obj);
>>> +
>>> +    set_feature(&cpu->env, ARM_FEATURE_V7);
>>> +    set_feature(&cpu->env, ARM_FEATURE_THUMB_DIV);
>>
>> Should we have a feature bit for "this is an R profile
>> core" ? For instance THUMB_DIV is mandatory for v7R
>> and so we could infer it in cpu realize.

> So is this best done as rename of ARM_FEATURE_MPU? We can still set R
> profile for ARMv5  MPU capable procs in much the same way we do with
> "EL2" and "EL3" for preV8.

So I originally suggested this because I read the bit in the
R5 TRM that says that the MPU is optional. But looking more
closely, I think that we would handle that by defining
FEATURE_MPU but 0 regions.

Bear in mind that FEATURE_MPU applies to M profile cores as
well. So if we find ourselves saying "MPU but not M profile"
a lot that might justify an R feature bit... But for now
we don't need to add it I guess.

-- PMM