From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ross Philipson Subject: Re: [PATCH V4 3/7] libxl: add pvusb API Date: Tue, 16 Jun 2015 12:51:32 -0400 Message-ID: <55805414.5010004@gmail.com> References: <1433906441-3280-1-git-send-email-cyliu@suse.com> <1433906441-3280-4-git-send-email-cyliu@suse.com> <21887.64856.265751.921367@mariner.uk.xensource.com> <21888.1191.40486.530231@mariner.uk.xensource.com> <21888.20366.133089.128189@mariner.uk.xensource.com> <55805127.1010105@eu.citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <55805127.1010105@eu.citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: George Dunlap , Ian Jackson Cc: Wei Liu , Ian Campbell , Chunyan Liu , "xen-devel@lists.xen.org" , Jim Fehlig , Simon Cao List-Id: xen-devel@lists.xenproject.org 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@lists.xen.org > http://lists.xen.org/xen-devel > -- Ross Philipson