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

[Alexander Graf]

On 13.02.2011, at 13:44, David Gibson wrote:

> On Sun, Feb 13, 2011 at 01:40:14PM +0100, Alexander Graf wrote:
>> 
>> On 13.02.2011, at 12:14, David Gibson wrote:
>> 
>>> On Sun, Feb 13, 2011 at 10:15:03AM +1100, Benjamin Herrenschmidt wrote:
>>>> On Sun, 2011-02-13 at 00:52 +0200, Blue Swirl wrote:
>>>>> On Sat, Feb 12, 2011 at 11:00 PM, Benjamin Herrenschmidt
>>> [snip]
>>>> Actually, one thing I noticed is that the current patches David posted
>>>> still have a single function with a switch/case statement for hcalls.
>>>> 
>>>> I'm not 100% certain what David long term plans are here, but in our
>>>> internal "WIP" tree, we've subsequently turned that into a mechanism
>>>> where any module can call powerpc_register_hypercall() to add hcalls.
>>>> 
>>>> So if David intends to move the "upstream candidate" tree in that
>>>> direction, then naturally, the calls in spapr_hcall.c are going to
>>>> disappear in favor of a pair of powerpc_register_hypercall() locally in
>>>> the vty module.
>>> 
>>> Ah, yeah.  I'm still not sure what to do about it.  I was going to
>>> fold the dynamic hcall registration into the patch set before
>>> upstreaming.  But then something paulus said made me rethink whether
>>> the dynamic registration was a good idea.  Still need to sort this out
>>> before the series is really ready.
>> 
>> We can surely move it to dynamic later on. I think the "proper" way
>> would be to populate a qdev bus and have the individual hypercall
>> receivers register themselves through -device creations. But Blue
>> really is the expert here :).
> 
> Ok, not sure what you mean here.  I already have a qdev bus for the
> VIO devices.  With my tentative dynamic model as devices are created
> on the bus they may register hypercalls as well.

Oh, guess I just overlooked that then, sorry :).

> Is that what you mean, or do you mean have a separate "hypercall"
> bus.  That sounds like serious overkill for a simple number->function
> translation.

Yup.


Alex