RE: [Xen-devel] Multiple PCI bus support

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: Guy Zana
>Sent: 2007å10æ10æ 17:30
>
>Hi,
>
>I saw that Xen support aÂtranslation between device/intx to GSI for a
>single PCI bus, I thought about adding multiple PCI bus support but
>disregard the bus information so the same device/intx on different
>busesÂwill be OR wired to the same GSI, sounds reasonable?ÂWhat
>other things do I need to support in Xen in order to add multiple PCI
>buses,Âassuming that secondary busesÂholds onlyÂPCI/PCIe devices?
>
>Thanks,
>Guy.
>

GSI wire is platform specific (Qemu as platform) and thus you can 
choose any policy including what you're proposing to Xen side.

However to support multiple PCI buses presented to HVM guest, 
the major work is in the Qemu:
        1. Emulate a virtual PCI-to-PCI bridge
        2. Add _PRT information in ACPI table under bridge node, which 
stays consistent to Xen's wire logic

If you want PCIe device to be seen as PCIe to HVM guest, you need to 
do more:
        3. Change above bridge to PCI-to-PCIe bridge (any standard spec?)
                (Then advanced PCIe feature like AER/ASPM can't be utilized)

But, any reason that assigned devices can't stay with current single bus 
model? :-)

Thanks,
Kevin

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