On Thu, 30 Jun 2016 15:07:27 +0200 Laszlo Ersek <[email protected]> wrote: > - What could be the difference between root ports and downstream ports? > (Hotplug into root ports seems to work fine.) Are OSes entitled to > allocate any unused address space (MMIO and IO) right when a device is > hot-plugged into a root port?
A possible difference is simply the depth of the hierarchy, the apertures on a root port come directly from the host bridge and there's no affect to other devices to disable and resize the root port apertures. In order to resize a switch downstream port aperture, the OS would need to touch multiple levels, which could affect peer devices already in operation. Does hotplug to a downstream switch port work if the hot added device is the only endpoint within that sub-hierarchy? I wouldn't necessarily be surprised either way, it seems like a complicated resource runtime reallocation issue that probably isn't very prevalent on real hardware. Thanks, Alex _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
