Re: [Qemu-devel] [Qemu-ppc] [PATCH: RFC] Adding BAR0 for e500 PCI controller

[Alexander Graf]

On 11.09.2012, at 21:05, Scott Wood <address@hidden> wrote:

> On 09/11/2012 06:33 AM, Alexander Graf wrote:
>> On 09/07/2012 08:58 PM, Scott Wood wrote:
>>> I wasn't suggesting that they be different devices.  I was suggesting
>>> that this isn't a property of the PCI controller, but rather of some
>>> other entity to which the PCI controller connects.  So maybe a reference
>>> to the associated CCSR object would be a qdev parameter, but not the
>>> size of that CCSR.
>> 
>> The first common place of information we get is the machine description.
>> So here we can do:
>> 
>>  create_device(e500_ccsr, CCSR_SIZE);
>>  create_device(e500_pci_host_controller, CCSR_SIZE);
>> 
>> Obviously code-wise this would look quite different from above, as
>> object constructor parameters go through qdev properties.
> 
> Keep in mind that in order to make MSIs work we need the BAR to actually
> be hooked up to CCSR, not just sized properly.  If qdev properties are
> really stable API as you indicated recently, we want to get this right
> and not introduce a short-term hack.

Right. So I like Andreas' proposal. We pass in a reference to the ccsr object 
into our host controller object as parameter. That reference could maybe be a 
real pointer (if supported) or by-path.

We can then use that to request the memory region that ccsr resides in. From 
that we can enumerate the size and also hook it up as BAR MMIO backing.


Alex

> 
> -Scott
> 
>