From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juergen Gross Subject: Re: [PATCH V3 4/6] xl: add pvusb commands Date: Thu, 21 May 2015 16:14:34 +0200 Message-ID: <555DE84A.7010900@suse.com> References: <1429415452-6161-1-git-send-email-cyliu@suse.com> <1429415452-6161-5-git-send-email-cyliu@suse.com> <5534B4D8.4010109@suse.com> <555C9B3A.6000906@suse.com> <555CA04F.20705@suse.com> <555CA77F.9030509@eu.citrix.com> <555D526C.4090603@suse.com> <555DB578.8070902@eu.citrix.com> <555DB8DE.50903@suse.com> <555DBD59.1070201@eu.citrix.com> <555DC84E.9090302@suse.com> <555DD745.10908@eu.citrix.com> <555DD8DC.3050102@suse.com> <555DE114.2020904@eu.citrix.com> <555DE3E1.3070202@suse.com> <555DE50B.6070804@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: <555DE50B.6070804@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 Cc: Lars Kurth , Wei Liu , Ian Campbell , Chunyan Liu , "xen-devel@lists.xen.org" , Ian Jackson , Simon Cao List-Id: xen-devel@lists.xenproject.org On 05/21/2015 04:00 PM, George Dunlap wrote: > On 05/21/2015 02:55 PM, Juergen Gross wrote: >> On 05/21/2015 03:43 PM, George Dunlap wrote: >>> On 05/21/2015 02:08 PM, Juergen Gross wrote: >>>> On 05/21/2015 03:01 PM, George Dunlap wrote: >>>>> On 05/21/2015 12:58 PM, Juergen Gross wrote: >>>>>> There might be existing users who know about "xm usb-assignable-list". >>>>> >>>>> Yes -- unfortunately something has to give: either we confuse new users >>>>> with two names that sound similar but do something different, or we >>>>> confuse former xm users by renaming their function, or we confuse >>>>> current xl users by renaming their function. There's badness to be had >>>>> whichever one we choose. I think renaming the xm function is the least >>>>> bad of all the options. >>>>> >>>>>> OTOH I don't care giving it another name, as long as the functionality >>>>>> is available. >>>>> >>>>> OK -- what about "usb-available-list"? Any objections / alternate >>>>> suggestions from anyone? >>>> >>>> Hmm, just another idea: >>>> >>>> xl usb-list -a >>>> >>>> could list all domains with assigned USB-devices and the currently not >>>> assigned devices as well. This would avoid the need for another command >>>> name. It would even be possible to omit the "-a". >>> >>> That works for me too, I guess. >>> >>> Can I suggest, though, that work on that functionality be detached from >>> getting the core pvusb functionality in? I can't really effectively do >>> the qemu side until it is in due to the cost of rebasing, and I would >>> really like to have both in for 4.6 if possible. >> >> Sure. >> >> I hope to have my pvusb backend in qemu ready until then, too. :-) >> In case the performance isn't too bad I'll have to make some changes to >> the libxl part as well, but this will result in some deletions only >> (qemu will do driver unbinding, this will no longer be required to be >> done by libxl). > > Right -- just like it's not necessary when qemu does emulated device > passthrough. :-) > > Out of curiosity, what's the motivation for doing pvusb in qemu? Will > there be an option, for instance, to switch usb devices from emulated > over to pv when the magic port is written to (as is done with disks & > network currently)? Doing it in qemu was a request when I sent my patches to do it in the kernel. :-) Doing pvusb in qemu really has advantages. Just by using a newer Xen you'll have pvusb backend support in Dom0. No need for a kernel update. Up to now I have no plan doing a switch of emulated USB devices to pv. TBH I don't think this is an important scenario. In case someone wants to add support for it I won't object. :-) Juergen