Re: [Qemu-devel] [PATCH arm-devs v1 2/6] target-arm/cpu: Convert reset CBAR to a property

[Andreas Färber]

Am 27.11.2013 11:15, schrieb Peter Maydell:
> On 27 November 2013 09:42, Andreas Färber <address@hidden> wrote:
>> If we turn it into a dynamic property, we could register it conditional
>> to ARM_FEATURE_CBAR.
> 
> Unfortunately feature flags only get set at realize (in the
> per-cpu init function), so we don't know at the point where
> we're registering properties whether to have this one or not.

1/6 sets it in instance_init actually. So instance_post_init might do.

> The other option would be to define an a9 cpu class init fn to
> put the property in.

Is it A9-only or would A15, A7, A12, etc. also need it?

>> The overall idea of the series makes sense to me. I would caution to
>> think about the naming scheme though - we might want to have a "cbar"
>> property to access the current value whereas we'll likely end up having
>> several reset values to configure over time.
> 
> Mmm, maybe. The approach I think we've taken in some other
> places (eg the cache controller) is to have the property names
> match the silicon's config or control signal names (which in
> this case would be PERIPHBASE), but they are not always
> consistent from CPU to CPU, so that might be more confusing
> than helpful. I don't think I have a strong opinion here, so I'd
> be happy with any vaguely consistent-looking plan.

Whatever name you choose, I was rather thinking of whether you may want
to call it, e.g., "foo-reset" or "reset-foo" to distinguish from plain
"foo". (Igor's x86 properties series uses "feat-foo" on Anthony's
suggestion to group and parse feature properties.)

Andreas

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg