From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ross Philipson Subject: Re: [PATCH V4 3/7] libxl: add pvusb API Date: Wed, 17 Jun 2015 09:48:01 -0400 Message-ID: <55817A91.9060209@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> <55805414.5010004@gmail.com> <5580F177.20702@suse.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; Format="flowed" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <5580F177.20702@suse.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: =?windows-1252?Q?J=FCrgen_Gro=DF?= , 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 06/17/2015 12:03 AM, J=FCrgen Gro=DF wrote: > On 06/16/2015 06:51 PM, Ross Philipson wrote: >> 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. > > See my other reply: this is the case. So Ian's suggestion would still > work. Ack, saw it, thanks. > > > Juergen > -- = Ross Philipson