On Mon, Sep 21, 2015 at 9:01 AM, Tang, Jason (ES) <Jason.Tang2@xxxxxxx> wrote: >> -----Original Message----- >> From: yhlu.kernel@xxxxxxxxx [mailto:yhlu.kernel@xxxxxxxxx] On Behalf Of >> Yinghai Lu >> Sent: Sunday, September 20, 2015 02:20 >> To: Bjorn Helgaas >> Cc: Tang, Jason (ES); linux-pci@xxxxxxxxxxxxxxx >> Subject: EXT :Re: [PATCH v1 3/7] PCI: Let kcmdline reserve bus numbers for >> hotplug bridges >> >> from bus [old_max, old_max+pci_hotplug_buses) could be used by other >> bridges, >> and other bridges could even get probed yet. > > I have tested the case where a subsequent bridge has not been probed yet and the BIOS is assigning it the same bus number. The behavior I observed is that conflicting bus numbers will be fixed during the second pass of PCI probing. See pci_scan_bridge() in drivers/pci/probe.c, lines 875-880 on tag v4.3-rc2. Also observe how patch 7 in my series updates the preceding conditional (line 874) to also check if the device is a hotpluggable bridge. > so there is a window that two peer bridges have been configured to overlapped bus range? >> Also it could even cross the boundary to other peer root bus range. > > I am not sure what you mean by this. Can you elaborate? couple peer bus range: root bus 0: [0,7f], root bus [80, ff] if one bridge under first root bus get add range blindly, it will cross the boundary at 0x7f. Yinghai -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
