[SeaBIOS] [RFC v2 0/3] Support multiple pci domains in pci_device
Marcel Apfelbaum
marcel.apfelbaum at gmail.com
Tue Aug 28 08:53:24 CEST 2018
Hi Gerd,
On 08/28/2018 09:07 AM, Gerd Hoffmann wrote:
> 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.
We already support multiple NUMA nodes. We want more devices.
Still, having 4x number of devices we previously supported is
a good step forward.
>
>> 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 $domain:00:00.0?
0000:$somewhere (On PCI domain 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.
Yes, we can.
Thanks Gerd!
Marcel
>
> cheers,
> Gerd
>
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