On Fri, Jul 24, 2015 at 05:51:04AM +0200, Juergen Gross wrote: > On 07/23/2015 09:08 PM, Greg KH wrote: > >On Thu, Jul 23, 2015 at 08:46:17AM +0200, Juergen Gross wrote: > >>On 07/23/2015 06:36 AM, Greg KH wrote: > >>>On Thu, Jul 23, 2015 at 06:04:39AM +0200, Juergen Gross wrote: > >>>>On 07/23/2015 01:46 AM, Greg KH wrote: > >>>>>On Tue, Jun 23, 2015 at 08:53:23AM +0200, Juergen Gross wrote: > >>>>>>Add the definition of pvUSB protocol used between the pvUSB frontend in > >>>>>>a Xen domU and the pvUSB backend in a Xen driver domain (usually Dom0). > >>>>>> > >>>>>>This header was originally provided by Fujitsu for Xen based on Linux > >>>>>>2.6.18. > >>>>>> > >>>>>>Changes are: > >>>>>>- adapt to Linux style guide > >>>>>> > >>>>>>Signed-off-by: Juergen Gross <jgross@xxxxxxxx> > >>>>>>--- > >>>>>> include/xen/interface/io/usbif.h | 252 +++++++++++++++++++++++++++++++++++++++ > >>>>> > >>>>>Why is this a different interface than the existing ones we have today > >>>>>(i.e. usbip?) Where is it documented? Do the Xen developers / > >>>> > >>>>The interface definition is living in the Xen git repository for several > >>>>years now: > >>>> > >>>>git://xenbits.xen.org/xen.git -> xen/include/public/io/usbif.h > >>> > >>>That's header file, not a document describing the api here. > >> > >>I suppose you want to tell me I should add something like: > >> > >>Documentation/DocBook/usb/API-struct-urb.html > > > >Somewhere that people can refer to that describes this public-facing API > >that "must not ever be broken or changed". If you want to put it in a > >documentation file, or a .h file, I don't care. > > > >>>>It is used e.g. in SUSE's xen kernel since 2.6.18. > >>> > >>>I am very aware of the amount of Xen crap in SuSE's kernel, don't use > >>>that as an excuse for me to merge it to mainline :) > >> > >>:-) > >> > >>Wasn't meant as an excuse, just a hint why the interface can't be the > >>same as for usbip. We have to ensure compatibility with those kernels > > > >This shouldn't be a kernel/kernel compability issue, as the api talks > >between Xen and the OS, not between different OSs, right? > > Depends on where the backend is living. It's the backend the frontend is > talking to. > > There is a backend in SUSE's kernels up to SLE12. So compatibility is > to be maintained to those kernels. Note, just because a distro merged an out of tree patch, does not mean that mainline has to accept the same api as-is :) > Looks as if in future there will be one in qemu. So there's only one other backend talking to this, in one distro? > >>and possibly other operating systems (BSD?, Windows?) which already > >>might be using pvUSB with a Dom0 based on the SUSE xen kernel. > > > >Are there other operating system drivers today that use this API? Is > >this an API in the Xen core today that we have to support? > > Yes. Yes to both? Which other operating systems have such a driver? > >Some more background / descriptions would be nice to have. > > I guess a documentation file giving a brief explanation about the > interfaces of Xen wouldn't be a bad idea. This could avoid discussions > like this. Yes it would. > It shouldn't define each interface, but the classes of interfaces which > are existing (between kernel and hypervisor, frontends and backends) > and the stability requirements. Headers like the one we are discussing > here could then refer to this document. Why shouldn't the protocol be documented? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
