PCIe hotplug

[Sadanand Warrier]

Hi
   I had  question about PCIe hotplug. We have hardware that is connected
to the host by means of two PCIe switches. i.e. the host sees a PCIe switch
connected to one of its buses and on the far side of that switch another
PCIe switch which has a PCIe device.
   It is possible that this device does not train its host facing PCIe
links before the server enumerates down its PCI bus and reaches those
links. It is also possible the PCIe switch to which the device is attached
has not been able to train its own links before server enumeration.
  Is PCIe hotplug built to work on schemes like this? Let us assume that
the hardware has been designed to trasmit a presence signal once the links
are trained but this could happen after the server enumeration?
  Incidentally does the server take advantage of the BIOS/UEFI enumeration?

Thanks

S
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