[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH V4 3/7] libxl: add pvusb API
On 06/16/2015 12:39 PM, George Dunlap wrote: On 06/16/2015 05:32 PM, Ian Jackson wrote:I have just discovered that the value used in /dev/disk/by-path is not from sysfs, or at least, not directly. udev cobbles it together with a bunch of string mangling, from information mostly from sysfs. There is no corresponding thing for usb devices. So Linux, the kernel, does not actually provide a stable device name string. This is obviously absurd, but I think fixing it is out of scope. I suggest we provide a facility to allow a user to specify a fnmatch glob pattern to be applied to the sysfs path. That way when they see their device is /devices/pci0000:00/0000:00:1d.7/usb1/1-1 they can write /devices/pci0000:00/0000:00:1d.7/usb*/*-1 which will match exactly and only the right thing.What about Juergen's system that has two usbN directories in a single pci node? Quoting: --- Hmm, perhaps. On my system I've got: /sys/devices/pci0000:00/0000:00:14.0/usb3/ /sys/devices/pci0000:00/0000:00:14.0/usb4/ So two busses on one pci bus address. Are usb3 and usb4 always in this order or are they sometimes just numbered the other way round? --- Assuming that usb3 and usb4 are actually distinct busses, and they might both have something plugged into port; in which case a glob like this: devices/pci0000:00/0000:00:14.0/usb*/*-1 Might match both of the following: /sys/devices/pci0000:00/0000:00:14.0/usb3/3-1 /sys/devices/pci0000:00/0000:00:14.0/usb4/4-1 Is that an xHCI host controller? If so that might be how the system represents the 2 logical (USB2/USB3) root hubs - each as its own separate bus. -George _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel -- Ross Philipson _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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