Re: Newbie, struggling with graphics and qemu monitor

Re: Newbie, struggling with graphics and qemu monitor

[Avi Kivity]

On 06/30/2009 06:35 PM, Michael Jinks wrote:
> Hi List.
>
> I'm taking my first look at KVM, using version 85, on a Gentoo system
> with kernel release 2.6.29.
>
> The gist of my problem right now is that I can't figure out how to
> access the monitor, and I've tried various things with no luck so far.
>
> My first hitch was that apparently SDL isn't working properly on my
> system, because running a console with SDL enabled just prints garbage
> characters to my xterm.  It seems that the mistranslation works both
> ways, because in cases where I happen to know what the guest system is
> displaying and can type blindly on its console, it doesn't behave the
> way I expect given the input I (think I) gave it.
>    

I'd start fixing this first.  Do other SDL applications work?  Is SDL 
fully installed?

-- 
error compiling committee.c: too many arguments to function

Re: Newbie, struggling with graphics and qemu monitor

[Anthony Liguori]

Avi Kivity wrote:
> On 06/30/2009 06:35 PM, Michael Jinks wrote:
>> Hi List.
>>
>> I'm taking my first look at KVM, using version 85, on a Gentoo system
>> with kernel release 2.6.29.
>>
>> The gist of my problem right now is that I can't figure out how to
>> access the monitor, and I've tried various things with no luck so far.
>>
>> My first hitch was that apparently SDL isn't working properly on my
>> system, because running a console with SDL enabled just prints garbage
>> characters to my xterm.  It seems that the mistranslation works both
>> ways, because in cases where I happen to know what the guest system is
>> displaying and can type blindly on its console, it doesn't behave the
>> way I expect given the input I (think I) gave it.
>>    
>
> I'd start fixing this first.  Do other SDL applications work?  Is SDL 
> fully installed?

Sounds like you have SDL configured to use libaa and are running qemu 
without DISPLAY set.

Regards,

Anthony Liguori

Re: Newbie, struggling with graphics and qemu monitor

[Michael Jinks]

On Tue, Jun 30, 2009 at 11:44 AM, Anthony Liguori<anthony@codemonkey.ws> wrote:
> Avi Kivity wrote:
>>
>
> Sounds like you have SDL configured to use libaa and are running qemu
> without DISPLAY set.

Sure enough, libsdl was built with aalib support...

I could swear I'd tried SDL from a VNC session but when I tried again
just now, up pops a display.

It freezes at Grub's "boot:" prompt and I can't get it to release my
mouse, I think because my <Ctl-Alt> isn't reaching the SDL window, but
this is progress...

I'm rebuilding libsdl with aalib switched off now, will see what happens next.

Re: Newbie, struggling with graphics and qemu monitor

[Michael Jinks]

On Tue, Jun 30, 2009 at 12:11 PM, Michael Jinks<michael.jinks@gmail.com> wrote:

> I'm rebuilding libsdl with aalib switched off now, will see what happens next.

Small differences:

Over ssh, the console boots with an SDL display, and my xterm window
title set to "caca for ncurses", but it's printing garbage and my
keystrokes don't appear to be reaching the guest.

If I try the same thing from a VNC desktop, I get the same behavior as
before: console pops up in a new window, displays fine, but never gets
past Grub's "boot:" prompt, my keystrokes don't do anything, and it
won't release my mouse.

Re: Newbie, struggling with graphics and qemu monitor

[Michael Jinks]

In an attempt to get past unrelated interference I just set up an X
session with only an xterm, used that to launch VNC connecting to my
KVM test host, and tried to launch my test guest again.  Same
behavior: Ctl-Alt patterns are ignored, as are any other keystrokes I
try to send to the qemu console window, which won't release my mouse.

I've looked but haven't found any way to attach a monitor process to
an already-running guest.  Is this possible?  Or do we only get a
monitor as a child process of the initial kvm invocation?

Given the way qemu and screen interact, using the same keystrokes to
initiate commands, it would be really useful to have some other way to
detach and re-attach to a kvm guest on the fly.



On Tue, Jun 30, 2009 at 12:25 PM, Michael Jinks<michael.jinks@gmail.com> wrote:
> On Tue, Jun 30, 2009 at 12:11 PM, Michael Jinks<michael.jinks@gmail.com> wrote:
>
>> I'm rebuilding libsdl with aalib switched off now, will see what happens next.
>
> Small differences:
>
> Over ssh, the console boots with an SDL display, and my xterm window
> title set to "caca for ncurses", but it's printing garbage and my
> keystrokes don't appear to be reaching the guest.
>
> If I try the same thing from a VNC desktop, I get the same behavior as
> before: console pops up in a new window, displays fine, but never gets
> past Grub's "boot:" prompt, my keystrokes don't do anything, and it
> won't release my mouse.
>

Re: Newbie, struggling with graphics and qemu monitor

[Charles Duffy]

Michael Jinks wrote:
> Given the way qemu and screen interact, using the same keystrokes to
> initiate commands, it would be really useful to have some other way to
> detach and re-attach to a kvm guest on the fly.

It's pretty easy to configure screen to use a different set of 
keystrokes. I find that ctrl+` is easy to type, interferes with far 
fewer applications than ctrl+a, and also makes it easier to work with 
nested screen sessions running on remote systems.

 From my ~/.screenrc:

escape ^``

Re: Newbie, struggling with graphics and qemu monitor

[Avi Kivity]

On 06/30/2009 09:33 PM, Michael Jinks wrote:
> In an attempt to get past unrelated interference I just set up an X
> session with only an xterm, used that to launch VNC connecting to my
> KVM test host, and tried to launch my test guest again.  Same
> behavior: Ctl-Alt patterns are ignored, as are any other keystrokes I
> try to send to the qemu console window, which won't release my mouse.
>
> I've looked but haven't found any way to attach a monitor process to
> an already-running guest.  Is this possible?  Or do we only get a
> monitor as a child process of the initial kvm invocation?
>    

Look up the -monitor option.

> Given the way qemu and screen interact, using the same keystrokes to
> initiate commands, it would be really useful to have some other way to
> detach and re-attach to a kvm guest on the fly.
>
>    

If you run qemu in screen, use -vnc.  X and screen don't mix.

-- 
error compiling committee.c: too many arguments to function

Re: Newbie, struggling with graphics and qemu monitor

[Michael Jinks]

(Thanks Avi, and all.  Sorry if my questions are basic.  More of them below.)

On Wed, Jul 1, 2009 at 3:43 AM, Avi Kivity<avi@redhat.com> wrote:
> On 06/30/2009 09:33 PM, Michael Jinks wrote:
>>
>> I've looked but haven't found any way to attach a monitor process to
>> an already-running guest.  Is this possible?  Or do we only get a
>> monitor as a child process of the initial kvm invocation?
>
> Look up the -monitor option.

Aha: I'd been looking in the "kvm" man page, which on my system looks
a lot like, but isn't exactly like, the qemu man page.  The qemu one
has the -monitor option.  (Is that a bug?  Should I pester the package
maintainers for my distro?)

But now that I've read it I don't understand it.  Quoting:

       -monitor dev
           Redirect the monitor to host device dev (same devices as the serial
           port).  The default device is "vc" in graphical mode and "stdio" in
           non graphical mode.

On my KVM host machine, there's no /dev/vc, even though I do have one
guest running.  I have /dev/vcs, /dev/vcs(1-12) and /dev/vcsa(1-7),
all major number 7 and owned by the "tty" group so they look
promising, but fuser doesn't show any of them being in use.

At any rate assuming that I started up a guest with, say, "-monitor
/dev/vcs1", how would I attach to that device afterward?  Does the kvm
command provide a way to do it or would I use a serial port handler,
like minicom?  Is there a default baud rate?

Again sorry if these are dumb questions, maybe I'm just not searching
on the right strings.

> If you run qemu in screen, use -vnc.  X and screen don't mix.

Okay, good to know.  But I'm still having the problem where vnc
clients crash unless the guest is in text-only mode, and I assume
that's going to be a problem when I try to install Windows guests.

Here's my VNC client output from booting a Gentoo install CD,
attaching VNC, and letting the guest boot into framebuffer mode.
Attachment works fine but the client crashes when the framebuffer
initializes, with "Rect too large":

[...]
  True colour: max red 255 green 255 blue 255, shift red 16 green 8 blue 0
Using shared memory PutImage
Tunneling active: preferring tight encoding
Rect too large: 1024x1 at (0, 0)

...and here's the (trimmed) output from waiting until the system is
done booting before trying to attach VNC:

[...]
  True colour: max red 255 green 255 blue 255, shift red 16 green 8 blue 0
Using shared memory PutImage
Tunneling active: preferring tight encoding
Zero size rect - ignoring
Zero size rect - ignoring
Zero size rect - ignoring
Rect too large: 1x0 at (3, 1024)
ShmCleanup called


Any recommendations for clients or options to try?  Does the tightvnc
client have known issues when attaching to a qemu server?

Re: Newbie, struggling with graphics and qemu monitor

[Avi Kivity]

On 07/01/2009 04:56 PM, Michael Jinks wrote:
> (Thanks Avi, and all.  Sorry if my questions are basic.  More of them below.)
>
> On Wed, Jul 1, 2009 at 3:43 AM, Avi Kivity<avi@redhat.com>  wrote:
>    
>> On 06/30/2009 09:33 PM, Michael Jinks wrote:
>>      
>>> I've looked but haven't found any way to attach a monitor process to
>>> an already-running guest.  Is this possible?  Or do we only get a
>>> monitor as a child process of the initial kvm invocation?
>>>        
>> Look up the -monitor option.
>>      
>
> Aha: I'd been looking in the "kvm" man page, which on my system looks
> a lot like, but isn't exactly like, the qemu man page.  The qemu one
> has the -monitor option.  (Is that a bug?  Should I pester the package
> maintainers for my distro?)
>
>    

No idea, really.

> But now that I've read it I don't understand it.  Quoting:
>
>         -monitor dev
>             Redirect the monitor to host device dev (same devices as the serial
>             port).  The default device is "vc" in graphical mode and "stdio" in
>             non graphical mode.
>
> On my KVM host machine, there's no /dev/vc, even though I do have one
> guest running.  I have /dev/vcs, /dev/vcs(1-12) and /dev/vcsa(1-7),
> all major number 7 and owned by the "tty" group so they look
> promising, but fuser doesn't show any of them being in use.
>
> At any rate assuming that I started up a guest with, say, "-monitor
> /dev/vcs1", how would I attach to that device afterward?  Does the kvm
> command provide a way to do it or would I use a serial port handler,
> like minicom?  Is there a default baud rate?
>    

vc is something internal to qemu (can reach it using alt-ctrl-2).  Try 
-monitor stdio or -monitor tcp::4321 (and telnet to it).

>> If you run qemu in screen, use -vnc.  X and screen don't mix.
>>      
>
> Okay, good to know.  But I'm still having the problem where vnc
> clients crash unless the guest is in text-only mode, and I assume
> that's going to be a problem when I try to install Windows guests.
>
> Here's my VNC client output from booting a Gentoo install CD,
> attaching VNC, and letting the guest boot into framebuffer mode.
> Attachment works fine but the client crashes when the framebuffer
> initializes, with "Rect too large":
>
>
>    

vnc and broken vnc clients don't mix.

> Any recommendations for clients or options to try?  Does the tightvnc
> client have known issues when attaching to a qemu server?
>    

I use vinagre.

-- 
error compiling committee.c: too many arguments to function

Re: Newbie, struggling with graphics and qemu monitor

[Michael Jinks]

On Tue, Jun 30, 2009 at 11:18 AM, Avi Kivity<avi@redhat.com> wrote:
> On 06/30/2009 06:35 PM, Michael Jinks wrote:
>>
>> My first hitch was that apparently SDL isn't working properly on my
>> system, because running a console with SDL enabled just prints garbage
>> characters to my xterm.
<snip>

> I'd start fixing this first.

Okay, that's helpful all by itself, apparently I'm not just up against
known bad behavior.

> Do other SDL applications work?  Is SDL fully
> installed?

I honestly don't know.  Several SDL packages are present and intact
according to my system's package manager (libsdl, sdl-gfx, sdl-image
and others), and the same package manager knows that SDL is a
dependency for kvm, so, maybe.  But when I go looking for simple SDL
demo programs to test with, I have more trouble.  The SDL web site's
list of demo programs is mostly made up of broken links, and the demo
programs I have been able to track down and install are failing for
reasons that don't look SDL-related. (For instance, "ballfield" from
http://olofson.net/examples.html will run, pops up a window briefly,
then crashes with "Could not load balls!")

So, any tips on how to test my SDL in a way that comes close to what
KVM expects?

One package which appears to use SDL is links, which does work fine in
a terminal window but I don't know if I'm actually exercising the SDL
facility or not, mostly it just looks like a curses app.