From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Jackson <Ian.Jackson@eu.citrix.com>
Subject: Re: [PATCH V4 3/7] libxl: add pvusb API
Date: Tue, 16 Jun 2015 12:10:26 +0100
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To: =?iso-8859-1?Q?J=FCrgen_Gro=DF?= <jgross@suse.com>
Cc: Wei Liu <wei.liu2@citrix.com>, Ian Campbell <ian.campbell@citrix.com>, George Dunlap <George.Dunlap@eu.citrix.com>, Chunyan Liu <cyliu@suse.com>, "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>, Jim Fehlig <jfehlig@suse.com>, Simon Cao <caobosimon@gmail.com>
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J=FCrgen Gro=DF writes ("Re: [Xen-devel] [PATCH V4 3/7] libxl: add pvusb AP=
I"):
> On 06/16/2015 12:41 PM, Ian Jackson wrote:
> > Is the busid more stable in the face of plug/unplug ?  This is the
> > normal reason for a more path-like device specification.
...
> Unfortunately the busid isn't stable at least across reboots.

I see.

Presumably the busdev isn't either.  We need to be let users specify
something that _is_ stable, obviously.

On my netbook I have this kind of thing in /etc/fstab:

/dev/disk/by-path/pci-0000:00:1d.7-usb-0:1:1.0-scsi-0:0:0:0-part1 /media/us=
b1 auto rw,user,noauto 0 0

Is a similar specification possible ?

> qemu does support specifying a USB device via <vendorId>:<productId>,
> which is stable even across reboots, but unfortunately it isn't
> guaranteed to be unique (you can have plugged in two devices of the
> same type).

Indeed.  That would also be a thing we should allow people to do.

AIUI some devices have serial numbers, which means you can distinguish
them ?

Ian.