Re: [Qemu-devel] Re: [PATCH 5/5] RFC: distinguish warm reset from cold reset.

[Blue Swirl]

On Mon, Aug 30, 2010 at 1:03 PM, Anthony Liguori <address@hidden> wrote:
> On 08/30/2010 03:50 AM, Paolo Bonzini wrote:
>>
>> On 08/30/2010 09:49 AM, Isaku Yamahata wrote:
>>>
>>> +/* those two functions are obsoleted by cold/warm reset API. */
>>> [qemu_register_reset/qemu_unregister_reset]
>>
>> Are they?
>
> Yes, but introduce more reset functions isn't the right approach.
>
> Reset should be a method of the device tree, not a stand alone function.

In theory the reset tree may be very different from device tree. In
practice the reset tree is probably very flat (global reset signal, a
few bus reset signals) so device tree approach may get the same
results.

IIRC on some HW ages ago the CPU could initiate an external device
reset (without resetting the CPU) but in that case the board caused
also CPU to be reset so it was useless.

One way to model the disjoint reset trees would be to use an explicit
qemu_irq signal for reset. It's a bit complex to set up compared to
the almost flat tree we want though.