Re: [Qemu-devel] Re: [PATCH 15/15] Implement the bus structure for PAPR virtual IO

[Benjamin Herrenschmidt]

On Sun, 2011-02-13 at 10:52 -0600, Anthony Liguori wrote:
> 
> A virtual bus is just an interface.  If all virtual devices that 
> interact via hcalls would all reside on the same virtual bus, then 
> having hypercalls registered through that interface makes sense
> because 
> you can associate hypercalls with particular devices.  This means
> that 
> you can automatically deregister on device removal and things like
> that.

I see. Well, VIO related h-calls are only part of the picture here, I
think we can live with having explicit de-registration if needed ;-)
Besides the h-call is still implemented even if no device -instance- is
currently plugged into the partition anyways. It just returns a (well
defined per-hcall) error code if the instance handle passed to it is
bogus.

> But I don't think this will work out well.  I think treating the 
> hypercalls as a simple dispatch table just like ioport would make
> sense.

Yup.

Cheers,
Ben.