Re: [Qemu-devel] [RFC v2 1/4] hw/arm/virt: Allow multiple agents to modify dt

[alvise rigo]

On Mon, Jan 5, 2015 at 5:41 PM, Peter Maydell <address@hidden> wrote:
> On 5 January 2015 at 16:14, alvise rigo <address@hidden> wrote:
>> On Mon, Jan 5, 2015 at 4:36 PM, Peter Maydell <address@hidden> wrote:
>>> Sorry, I think I must have missed this series first time around.
>>> I'm not convinced -- I don't see any reason why we should treat
>>> the PCI host controller differently from other devices in the
>>
>> The reason for this is that the PCI host controller needs to generate
>> its device node after all the PCI devices have been added to the bus
>> (also those specified with the -device option).
>> This is required by the interrupt-map node property, that specifies
>> for each PCI device an interrupt map entry. Since we have one device
>> requiring this 'postponed' node generation, this patch allows also
>> other devices to do the same.
>
> What? This doesn't sound right -- you can have hot-plugged PCI
> devices, for a start. Device tree is only supposed to be
> needed for the bits of hardware that can't be probed, and
> we can rely on PCI itself to probe the other devices.

OK, I see.

>
> interrupt-map as far as I can tell just specifies how the
> interrupt lines are mapped for each PCI slot; it won't
> change based on whether devices are present or not. The
> example in the wiki:
>  http://devicetree.org/Device_Tree_Usage#Advanced_Interrupt_Mapping
> cares about number of slots, but that's all.

So I suppose we need to define a fixed number of PCI slots according
to the number of interrupts available in mach-virt. In this regard,
should this number be a qdev property?

Thank you,
alvise

>
> thanks
> -- PMM