This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] Xen frame buffer related

To: Dushmanta Mohapatra <dushmanta.mohapatra@xxxxxxxxx>
Subject: Re: [Xen-devel] Xen frame buffer related
From: Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>
Date: Fri, 4 Apr 2008 16:40:53 +0200
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Delivery-date: Fri, 04 Apr 2008 07:42:04 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <46009afb0804030657rd1c2443jc3d4406235633417@xxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Mail-followup-to: Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>, Dushmanta Mohapatra <dushmanta.mohapatra@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
References: <46009afb0804030657rd1c2443jc3d4406235633417@xxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mutt/1.5.12-2006-07-14

Dushmanta Mohapatra, le Thu 03 Apr 2008 09:57:11 -0400, a écrit :
> I see two xenfb.c files in the Xen (3.2) source. One in tools/ioemu/hw/ and 
> the
> other in linux-2.6.18-xen.hg/drivers
> /xen/fbfront/. So I think the first one is the userspace-backend and the 
> second
> one is the kernel-space front-end.

That's it.

> I do not understand why originally the
> back-end was not made a part of kernel like other devices?

Why should it be?  In the case of PVFB, he backend is responsible for
actually showing the frame buffer.  A userspace X11 application or VNC
server is thus the logical way.

> Also could you please tell me how to use this backend userspace tool.

You just need to add

vfb = [ 'type=sdl' ]

if you want to have an SDL window showing up when you start your domain,

vfb = [ 'type=vnc' ]

if you want to have a VNC server started instead.

> If I have understood it correctly then in Xen 3.1, this  back end tool  uses
> VNCServer for displaying  the contents  of  Frontend  frambuffer.  So what has
> changed with the use of QEMU.

There is now the SDL choice.

> Finally just to give you an idea about my project:  Lets suppose a domU gets
> migrated from a Physical machine having a display of X1xY1 to another physical
> machine having a display of X2xY2.

In the unstable tree, there is an OpenGL rendering which can accomodate
with this by rescaling the frame buffer.

> Also a similar example can be a domU getting migrated from a machine
> having one type of keyboard to a machine having another type of
> keyboard.

Mmm, you may have a problem here, because PVFB uses Linux keycodes, not
keysyms.  I.e. whatever the configuration of the host machine, the guest
keyboard configuration will be used.

> If I see Xen
> 3.2 code in the user space backend framebuffer code (/tools/ioemu/hw/xenfb.c) 
> I
> see functions like "static int xenfb_read_frontend_fb_config(struct xenfb
> *xenfb)" and "static int xenfb_read_frontend_kbd_config(struct xenfb *xenfb)".

That's to get the initial size, but in the unstable tree we now have a
PVFB event that permits the guest to change the size dynamically.


Xen-devel mailing list

<Prev in Thread] Current Thread [Next in Thread>