Re: [Qemu-devel] Re: [PATCH 7/7] [RFC] pci bus: preliminary for multi pci bus support.

[Markus Armbruster <armbru@redhat.com>]

Isaku Yamahata <yamahata@valinux.co.jp> writes:

> On Tue, Jun 02, 2009 at 10:13:19AM +0300, Avi Kivity wrote:
>> Isaku Yamahata wrote:
>> >This patch is preliminary for multi pci bus support to
>> >add -pci option.
>> >  
>> 
>> What is the motivation for this work?
>
> -pci might be too generic. -pci_bridge or something else might be
> better. I think, eventually they would be replaced with config file work.
> So this option isn't so important.

To make use of this code, we need a way to create PCI bridges.  If we
can't have an option, maybe we could create bridges as needed, just like
we create SCSI controllers.  But I don't like that at all.

I wouldn't advise waiting for completion of the config file stuff.

> The short term motivation is 128+ pci slot support.

Sorely needed, in my opinion.

> I know Markus has tried on kvm before and was rejected because
> of scalability. As he also wants it, I'm willing to collaborate with him.
>
> The long term motivation is to support MMCFG and PCIe port emulator,
> then eventually PCIe native direct attach support including
> PCIe native functionality like AER.
> This requires more newer chipset emulation than piix and more.

Good stuff.