Re: [Qemu-devel] [SeaBIOS] [RFC v2 0/3] Support multiple pci domains in pci_device

[Gerd Hoffmann]

  Hi,

> Since we will not use all 256 buses of an extra PCI domain,
> I think this space will allow us to support more PCI domains.

Depends on the use case I guess.  If you just need many pcie devices
this probably doesn't help.  If you want them for numa support then yes,
more domains with less devices each can be useful then.

> How will the flow look like ?
> 
> 1. QEMU passes to SeaBIOS information of how many extra
>    PCI domains needs, and how many buses per domain.
>    How it will pass this info? A vendor specific capability,
>    some PCI registers or modifying extra-pci-roots fw_cfg file?

Where is the pxb-pcie device?  0000:$somewhere?  Or $domain:00:00.0?

> 2. SeaBIOS assigns the address for each PCI Domain and
>     returns the information to QEMU.
>     How it will do that? Some pxb-pcie registers? Or do we model
>     the MMCFG like a PCI BAR?

If we can access pxb-pcie registers before configuring MMCFG then yes,
we should use pxb-pcie registers for that.

cheers,
  Gerd