Re: [Qemu-devel] [PATCH arm-midr v2 1/2] ARM: Convert MIDR to a property

[Peter Maydell <peter.maydell@linaro.org>]

On 19 January 2014 00:59, Peter Crosthwaite
<peter.crosthwaite@xilinx.com> wrote:
> Do you even need this now? The normal arrayified dc->props properties
> are added at device::init time. As TYPE_DEVICE is a parent class, its
> init function is called before CPUs (normal inits are called in
> parent->child order, the post_inits are reverse). This means the
> cpu::init fns should correctly set the device-specific default after
> device::init, trampling the bogus default defined in the property
> array.
>
> All of this however assumes that MIDR is unconditionally existent for
> all ARMCPU. Peter, are you able to confirm that thats ok before we
> commit to this implementation over the conditional post_init approach?

IIRC ARMv4 and earlier didn't define the MIDR, but we don't
actually emulate any of those. In general, my intent with all these
constant fields in the ARMCPU struct was that we'd end up making
them just properties available on all ARMCPU objects, and if the
particular subtype of ARMCPU happened not to have FP and so
didn't need the reset_fpsid, for example, it would just ignore whatever
value you set the property to. I don't think we need to tie ourselves
in knots to restrict the properties to particular CPUs if it is too
implementationally awkward (though it would be nice if we can
tie them to ARM_FEATURE_* bits for more or less free).

thanks
-- PMM