From: Juergen Gross <email@example.com>
To: George Dunlap <George.Dunlap@eu.citrix.com>
Cc: Ian Jackson <firstname.lastname@example.org>,
Stefano Stabellini <email@example.com>,
Wei Liu <firstname.lastname@example.org>, Chunyan Liu <email@example.com>,
Subject: Re: [PATCH 3/3] libxl: add new pvusb backend "qusb" provided by qemu
Date: Wed, 30 Mar 2016 06:43:57 +0200 [thread overview]
Message-ID: <56FB598D.firstname.lastname@example.org> (raw)
On 29/03/16 12:35, Juergen Gross wrote:
> On 29/03/16 11:45, George Dunlap wrote:
>> On Fri, Mar 25, 2016 at 6:09 AM, Juergen Gross <email@example.com> wrote:
>>> On 24/03/16 21:07, Wei Liu wrote:
>>>> On Fri, Mar 18, 2016 at 09:24:26AM +0100, Juergen Gross wrote:
>>>>> On 17/03/16 17:55, George Dunlap wrote:
>>>>>> On Thu, Mar 10, 2016 at 3:00 PM, Juergen Gross <firstname.lastname@example.org> wrote:
>>>>>>> Add a new pvusb backend type "qusb" which is provided by qemu. It can
>>>>>>> be selected either by specifying the type directly in the configuration
>>>>>>> or it is selected automatically by libxl in case there is no "usbback"
>>>>>>> driver loaded.
>>>>>>> Signed-off-by: Juergen Gross <email@example.com>
>>>>>> Oh, last thing -- shouldn't we have a way for libxl to tell whether
>>>>>> qemu can provide a qusb backend before we offer to start it up?
>>>>> How? Is this possible for qdisk? Or for an emulated frame buffer?
>>>> I don't think it is possible at the moment. But I think you might be
>>>> able to do it either via qmp command or parsing qemu help string. The
>>>> latter functionality is implemented in Ian's device model deprivilege
>>>> patch series IIRC -- but it is not yet merged either.
>>> Won't help for qusb, as there is no qemu parameter or help text related
>>> to the backend. It would be possible to add a qmp command to print the
>>> supported backend types, of course.
>> Well as I understand it, for qemu-upstream we can't assume what
>> version of qemu we'll end up getting: we need to be compatible with
>> recent releases of qemu which don't provide qusb. Which I'm pretty
>> sure means failing gracefully (i.e., giving a sensible warning
>> message) if someone tries to add qusb when their qemu binary doesn't
>> support it.
>> If you can tell from the qemu failure that qusb is at fault, that's OK
>> I think; but if not, I think you'll have to add some way to query
>> whether qusb is supported by the qemu binary before starting it.
> So we would want a qemu command line option (e.g. -xen-help) printing
> the supported pv backends. I think this should be easy to setup.
Actually there is a solution which is _really_ simple: before setting
it's state to "running" in xenstore, qemu could write the supported
backend types to xenstore, too. I'd add a xenstore directory
containing a directory for each supported backend. By using a directory
for each backend it would even be possible to indicate supported
features and/or parameters in the future.
"qusb" backend would be regarded to be supported only if
"qdisk" would be regarded to be supported if either:
is existing or:
is not existing.
Xen-devel mailing list
prev parent reply other threads:[~2016-03-30 4:43 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-10 15:00 [PATCH 0/3] libxl: add support for qemu base pvusb backend Juergen Gross
2016-03-10 15:00 ` [PATCH 1/3] libxl: make libxl__need_xenpv_qemu() operate on domain config Juergen Gross
2016-03-17 16:53 ` George Dunlap
2016-03-18 8:23 ` Juergen Gross
2016-03-10 15:00 ` [PATCH 2/3] libxl: add domain config parameter to force start of qemu Juergen Gross
2016-03-17 16:06 ` George Dunlap
2016-03-18 8:11 ` Juergen Gross
2016-03-21 14:28 ` George Dunlap
2016-03-21 14:44 ` Juergen Gross
2016-03-10 15:00 ` [PATCH 3/3] libxl: add new pvusb backend "qusb" provided by qemu Juergen Gross
2016-03-17 16:39 ` George Dunlap
2016-03-18 8:22 ` Juergen Gross
2016-03-17 16:55 ` George Dunlap
2016-03-18 8:24 ` Juergen Gross
2016-03-24 20:07 ` Wei Liu
2016-03-25 6:09 ` Juergen Gross
2016-03-29 9:45 ` George Dunlap
2016-03-29 10:35 ` Juergen Gross
2016-03-30 4:43 ` Juergen Gross [this message]
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).