From: George Dunlap <George.Dunlap@eu.citrix.com>
To: Juergen Gross <jgross@suse.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
Wei Liu <wei.liu2@citrix.com>, Chunyan Liu <cyliu@suse.com>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
Subject: Re: [PATCH 3/3] libxl: add new pvusb backend "qusb" provided by qemu
Date: Thu, 17 Mar 2016 16:39:07 +0000 [thread overview]
Message-ID: <CAFLBxZa4YmiYLX9SG+Y6tzsbHQ6VzrCVdc=vrOj-APatrBTvqQ@mail.gmail.com> (raw)
In-Reply-To: <1457622051-30189-4-git-send-email-jgross@suse.com>
On Thu, Mar 10, 2016 at 3:00 PM, Juergen Gross <jgross@suse.com> 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 <jgross@suse.com>
It would be awesome if we could get a patch like this in for 4.7.
However...
> ---
> docs/man/xl.cfg.pod.5 | 11 +++-
> tools/libxl/libxl_device.c | 3 +-
> tools/libxl/libxl_dm.c | 8 +++
> tools/libxl/libxl_internal.h | 1 +
> tools/libxl/libxl_pvusb.c | 102 +++++++++++++++++++++++++++--------
> tools/libxl/libxl_types.idl | 1 +
> tools/libxl/libxl_types_internal.idl | 1 +
> 7 files changed, 101 insertions(+), 26 deletions(-)
>
> diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
> index 1dde66b..06eeb42 100644
> --- a/docs/man/xl.cfg.pod.5
> +++ b/docs/man/xl.cfg.pod.5
> @@ -737,8 +737,15 @@ Possible B<KEY>s are:
>
> =item B<type=TYPE>
>
> -Specifies the usb controller type. Currently only 'pv' and 'auto'
> -are supported.
> +Specifies the usb controller type.
> +
> +"pv" denotes a kernel based pvusb backend.
> +
> +"qusb" specifies a qemu base backend for pvusb.
> +
> +"auto" (the default) determines whether a kernel based backend is installed.
> +If this is the case, "pv" is selected, "qusb" will be selected if no kernel
> +backend is currently available.
I'm going back and forth a bit about whether having a "qusb" option
here makes the most sense, or whether it makes more sense to have a
separate option, like "backendtype" (as we have for disks).
The reason I suggested having "type" here at all is that libxl cannot
know ahead of time whether the guest has pvusbfront available. It
*can*, however, tell whether pvusbback is available (as your code
demonstrates).
On the other hand -- given that qemu will shortly have pvusbback, I'm
wondering if it's possible to make pvusbfront do something similar to
what the blkfront drivers do -- write a magic port that tell qemu,
"Actually, I have pvusb drivers; unplug the emulated controller."
From a UI point of view that would be the best, right? Just like
disks or network cards -- you can simply say you want a controller,
and you automatically get the most appropriate kind based on what the
kernel you run actually has available.
I think you've been working on the pvusbfront drivers for Linux, as
well as the qusb backend in qemu -- do you think that's workable?
If so, I think adding 'qusb' to this field is probably the right thing to do.
One technical question...
> @@ -1559,7 +1616,6 @@ int libxl_ctrlport_to_device_usbdev(libxl_ctx *ctx,
> dompath = libxl__xs_get_dompath(gc, domid);
>
> fe_path = GCSPRINTF("%s/device/vusb/%d", dompath, ctrl);
Did you miss a vusb -> %s here?
-George
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next prev parent reply other threads:[~2016-03-17 16:39 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 [this message]
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
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