Re: [Qemu-devel] [SeaBIOS] [RFC PATCH 0/2] Allow RedHat PCI bridges reserve more buses than necessary during init

[Marcel Apfelbaum <marcel@redhat.com>]

On 20/07/2017 9:52, Gerd Hoffmann wrote:
> On Wed, 2017-07-19 at 16:20 +0300, Aleksandr Bezzubikov wrote:
>> Now PCI bridges (and PCIE root port too) get a bus range number in
>> system init,
>> basing on currently plugged devices. That's why when one wants to
>> hotplug another bridge,
>> it needs his child bus, which the parent is unable to provide.
>> The suggested workaround is to have vendor-specific capability in
>> RedHat generic pcie-root-port
>> that contains number of additional bus to reserve on BIOS PCI init.
> 

Hi Gerd,
Thanks for looking into this.

> Where is the qemu patch for this?
> 

On the way, Aleksandr is working on it, should
be ready soon.

> What about window sizes?  IIRC there was a plan to provide allocation
> hints for them too ...

Yes, is in my TODO list, however not as part of Aleksandr's series
which aims to provide PCIe-PCI bridge hotplug support.
I should mention that for this case both Windows and Linux guests
(modern OSes) trigger correctly IO/MEM resource re-balancing
process and succeeds to complete the hotplug operation.

Thanks,
Marcel

> 
> cheers,
>    Gerd
>