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

[Anthony Liguori]

On 08/31/2010 09:03 AM, Avi Kivity wrote:
> There's no such thing as a global reset.  There's a trace on the board 
> that's called RESET that's connected to many chip's RESET input (but 
> perhaps not all).  A PCI bus controller will likely propagate its 
> RESET input into the PCI reset signal, however it's called.  So 
> individual RESET traces are connected by chips, which have different 
> conditions for asserting them.
>
> So yes, we need a custom traversal.  Some bus controllers will block 
> off RESET completely, some will pass it through, some can reset the 
> devices on their bus independently of the controller's RESET input, if 
> it has one.
>
> (but I think we're drifting off into pointlessness here)

That's my source of confusion.  I know hardware does a custom 
transversal but from a functional perspective, do we care?

So far, no one has answered this with, "yes, because device XX 
propagates in a specific ordering of child a, b, c, d..." which I take 
to mean that the answer is no.

Regards,

Anthony Liguori