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* Xen frame buffer related
@ 2008-04-03 13:57 Dushmanta Mohapatra
  2008-04-04 14:40 ` Samuel Thibault
  2008-04-04 15:59 ` Markus Armbruster
  0 siblings, 2 replies; 8+ messages in thread
From: Dushmanta Mohapatra @ 2008-04-03 13:57 UTC (permalink / raw)
  To: xen-devel


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Hi,

Thanks for the response. It really helps. I have a few more questions.

First of all I do not know what PVOPS means. I searched for it but did not
find any thing convincing. So is that only for the official linux tree? In
Xen website  we still get the linux 2.6.18 kernel which gets patched for
Xen.  So  for this 2.6.18 Xeno-Linux version do I need your patches for
correct operation. Can I use the PVOPS tree at present for my Dom0? As far
as I know only 2.6.18 version of Dom0 is currently available. I have read
that we can use recent kernels like 2.6.23 etc for DomU though I myself use
the same kernel for both Dom0 and DomU.

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.  I do not understand why originally the back-end was not made a
part of kernel like other devices? Also could you  please tell me how to use
this backend  userspace tool.  Any  pointer  will do.

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. Also I did not understand what you meant
by "to avoid having two VNC servers".
Is it related to one for FV and another for PV.

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. So our project tries to
dynamically configure the front end/ back-end so that the user does not
notice a difference. 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.  So  do you think  support for this  is already available in
Xen 3.2.  Are we  doing some  thing that  others have already done?  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)". So I am just wondering
what  these functions are for?

I am sorry that the mail is a bit long. I really appreciate all your help.

Thanks,
Dushmanta



Hello,
>
>
> I have been investigating about Xen Frame Buffer regarding a project that
I
> am involved with.

I'm curious, can you tell me about it?

> I am facing some problems. So while searching on the net I found your post
> at
http://lists.xensource.com/archives/html/xen-devel/2008-02/msg00717.html

This is the pvops para-virtual framebuffer (PVFB).  The patch is for
Linus's tree.

> Now browsing through the source I find xenfb frontend related files at
> linux-2.6.18-xen.hg/drivers/xen/fbfront/xenfb.c (also xenkbd.c).  (I use
Xen
> 3.2 compiled from source).

This is the old, non-pvops Xen Linux tree.

This tree is much too old (2.6.18) to be useful for our users.  We
used to extract the Xen patch from that tree and forward-port it to
less obsolete kernel versions, but that was not sustainable, so we
stopped.

The only future for Xen's Linux part, as far as I'm concerned, is
going upstream, into Linus's tree.  That means porting it to the pvops
interface.  Still a work in progress: domU is usable, but dom0 needs
more work.  The patch you quoted above is part of that work in
progress.

I recommend to base any new work on pvops kernels, if at all
practical.

> So what exactly are the files you are referring to in your post.
>
> Also could you please give me a brief idea about the interaction between
> QEMU and xenfb in Xen 3.2 and what exactly has changed from Xen 3.1.
>
>
> Thanks,
> Dushmanta

I don't remember exact timing of changes.  Peruse the Mercurial
repository.

PVFB consists of a frontend in domU (device driver in kernel space),
and a backend in dom0 user space.

The initial version implemented backend as a separate program (source
in xen-unstable.hg/tools/xenfb/).  Later on, we merged it into QEMU,
chiefly to avoid having two different VNC servers.

If you have more questions, consider asking on the mailing list, where
more people than just you can profit from my answers :)

Markus

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_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

^ permalink raw reply	[flat|nested] 8+ messages in thread
* Xen frame buffer related
@ 2008-04-03 14:21 Dushmanta Mohapatra
  0 siblings, 0 replies; 8+ messages in thread
From: Dushmanta Mohapatra @ 2008-04-03 14:21 UTC (permalink / raw)
  To: Xen-devel


[-- Attachment #1.1: Type: text/plain, Size: 4288 bytes --]

Hi,

Thanks for the response. It really helps. I have a few more questions.

First of all I do not know what PVOPS means. I searched for it but did not
find any thing convincing. So is that only for the official linux tree? In
Xen website  we still get the linux 2.6.18 kernel which gets patched for
Xen.  So  for this 2.6.18 Xeno-Linux version do I need your patches for
correct operation. Can I use the PVOPS tree at present for my Dom0? As far
as I know only 2.6.18 version of Dom0 is currently available. I have read
that we can use recent kernels like 2.6.23 etc for DomU though I myself use
the same kernel for both Dom0 and DomU.

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.  I do not understand why originally the back-end was not made a
part of kernel like other devices? Also could you  please tell me how to use
this backend  userspace tool.  Any  pointer  will do.

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. Also I did not understand what you meant
by "to avoid having two VNC servers".
Is it related to one for FV and another for PV.

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. So our project tries to
dynamically configure the front end/ back-end so that the user does not
notice a difference. 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.  So  do you think  support for this  is already available in
Xen 3.2.  Are we  doing some  thing that  others have already done?  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)". So I am just wondering
what  these functions are for?

I am sorry that the mail is a bit long. I really appreciate all your help.

Thanks,
Dushmanta



Hello,
>
>
> I have been investigating about Xen Frame Buffer regarding a project that
I
> am involved with.

I'm curious, can you tell me about it?

> I am facing some problems. So while searching on the net I found your post
> at
http://lists.xensource.com/archives/html/xen-devel/2008-02/msg00717.html

This is the pvops para-virtual framebuffer (PVFB).  The patch is for
Linus's tree.

> Now browsing through the source I find xenfb frontend related files at
> linux-2.6.18-xen.hg/drivers/xen/fbfront/xenfb.c (also xenkbd.c).  (I use
Xen
> 3.2 compiled from source).

This is the old, non-pvops Xen Linux tree.

This tree is much too old (2.6.18) to be useful for our users.  We
used to extract the Xen patch from that tree and forward-port it to
less obsolete kernel versions, but that was not sustainable, so we
stopped.

The only future for Xen's Linux part, as far as I'm concerned, is
going upstream, into Linus's tree.  That means porting it to the pvops
interface.  Still a work in progress: domU is usable, but dom0 needs
more work.  The patch you quoted above is part of that work in
progress.

I recommend to base any new work on pvops kernels, if at all
practical.

> So what exactly are the files you are referring to in your post.
>
> Also could you please give me a brief idea about the interaction between
> QEMU and xenfb in Xen 3.2 and what exactly has changed from Xen 3.1.
>
>
> Thanks,
> Dushmanta

I don't remember exact timing of changes.  Peruse the Mercurial
repository.

PVFB consists of a frontend in domU (device driver in kernel space),
and a backend in dom0 user space.

The initial version implemented backend as a separate program (source
in xen-unstable.hg/tools/xenfb/).  Later on, we merged it into QEMU,
chiefly to avoid having two different VNC servers.

If you have more questions, consider asking on the mailing list, where
more people than just you can profit from my answers :)

Markus

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_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2008-04-05  8:22 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2008-04-03 13:57 Xen frame buffer related Dushmanta Mohapatra
2008-04-04 14:40 ` Samuel Thibault
2008-04-04 15:59 ` Markus Armbruster
2008-04-04 19:20   ` Dushmanta Mohapatra
2008-04-05  8:22     ` Markus Armbruster
2008-04-04 19:59   ` Jeremy Fitzhardinge
2008-04-05  7:43     ` Markus Armbruster
  -- strict thread matches above, loose matches on Subject: below --
2008-04-03 14:21 Dushmanta Mohapatra

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