From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: Juergen Gross <jgross@suse.com>,
linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com,
david.vrabel@citrix.com, boris.ostrovsky@oracle.com,
linux-usb@vger.kernel.org
Subject: Re: [Patch V4 1/3] usb: Add Xen pvUSB protocol description
Date: Fri, 24 Jul 2015 15:25:18 -0400 [thread overview]
Message-ID: <20150724192518.GF12824@l.oracle.com> (raw)
In-Reply-To: <20150724185747.GB21453@kroah.com>
On Fri, Jul 24, 2015 at 11:57:47AM -0700, Greg KH wrote:
> 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@suse.com>
> > >>>>>>---
> > >>>>>> 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?
No. All distros which use QEMU will have it.
>
> > >>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?
Windows XP, Windows 7, Windows 8, and so on using one of the Xen
PV drivers.
The old RHEL5 PV kernels, SLES kernels, and NetBSD [edit: Only
the header file, odd]
>
> > >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?
I presume you mean the wire spec? Like what is in the memory and
exchanged between the guests? Classes sounds like an C++ thing :-)
There is also the XenBus which does the negotiation of parameters
(like the VirtioPCI spec) - that could be expanded to enumerate
the USB drivers ones ?
>
> thanks,
>
> greg k-h
next prev parent reply other threads:[~2015-07-24 19:25 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-23 6:53 [Patch V4 0/3] xen, usb: support pvUSB frontend driver Juergen Gross
[not found] ` <1435042405-14235-1-git-send-email-jgross-IBi9RG/b67k@public.gmane.org>
2015-06-23 6:53 ` [Patch V4 1/3] usb: Add Xen pvUSB protocol description Juergen Gross
2015-07-22 23:46 ` Greg KH
2015-07-23 4:04 ` Juergen Gross
[not found] ` <55B067D7.3030904-IBi9RG/b67k@public.gmane.org>
2015-07-23 4:36 ` Greg KH
[not found] ` <20150723043653.GA31524-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2015-07-23 6:46 ` Juergen Gross
[not found] ` <55B08DB9.60902-IBi9RG/b67k@public.gmane.org>
2015-07-23 9:38 ` [Xen-devel] " David Vrabel
2015-07-23 19:08 ` Greg KH
2015-07-23 21:29 ` Pasi Kärkkäinen
2015-07-24 3:51 ` Juergen Gross
[not found] ` <55B1B628.7090200-IBi9RG/b67k@public.gmane.org>
2015-07-24 18:57 ` Greg KH
2015-07-24 19:25 ` Konrad Rzeszutek Wilk [this message]
[not found] ` <1435042405-14235-2-git-send-email-jgross-IBi9RG/b67k@public.gmane.org>
2015-07-23 9:39 ` [Xen-devel] " David Vrabel
2015-06-23 6:53 ` [Patch V4 2/3] usb: Introduce Xen pvUSB frontend (xen hcd) Juergen Gross
[not found] ` <1435042405-14235-3-git-send-email-jgross-IBi9RG/b67k@public.gmane.org>
2015-07-23 9:47 ` David Vrabel
2015-06-23 6:53 ` [Patch V4 3/3] xen: add Xen pvUSB maintainer Juergen Gross
2015-07-20 5:13 ` [Patch V4 0/3] xen, usb: support pvUSB frontend driver Juergen Gross
2016-03-17 19:43 ` Oleksandr Tyshchenko
[not found] ` <CAJEb2DHesrZn0H=d4KVn6sbyXFA8ykdUFMftyAZqbwSKk_JKKQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-03-18 8:32 ` [Xen-devel] " Juergen Gross
2016-03-18 12:28 ` Oleksandr Tyshchenko
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