Re: [Xen-users] Problem setting up VNC on SLES10 HVM DomU

[Jonathan Ervine <jervine@xxxxxxxxxx>]

On Sunday 27 January 2008 18:11:57 Evan Lavelle wrote:
> I've just uneventfully installed SLES10 as an HVM DomU (after finding
> out, the hard way, that OpenSUSE 10.3 won't install on Intel VT).

Echoing some of Jim's comments too. openSUSE 10.3 absolutely installs on 
Intel-VT and AMD-V hardware. It's not mentioned anywhere, but what is 
the Dom0? (I would guess SLES 10?)

> This almost went without a hitch, but I've been banging my head
> against a brick wall for a few hours trying to get VNC working. I can
> get a remote desktop, but a few seconds after I log in to the remote
> desktop, the screen goes blank (just after I get the "Suse linux
> enterprise 10" screen). Bizarrely, the SLES10 screen saver *does*
> appear on the remote desktop a few minutes later. Another odd thing
> is that the SDL window on my Dom0 has exactly the same behaviour:
> when I log in on the remote vnc client, I get some startup activity
> on the SDL window for a few seconds, and then it goes blank. The
> screensaver starts on the SDL window at the same time as on the vnc
> client. The only way I can talk to the DomU is on ssh.

When I first read this I thought you were trying to set up remote access 
to Dom0, but after a few subsequent reads it seems as though you want 
access via VNC to a DomU? A couple of questions:
1. Assuming SLES 10 is your Dom0, are you patched up to date, 
particularly with SP1? Generally, HVM installations with SP1 by default 
use a VNC session rather than SDL for viewing the DomU on Dom0.
2. Why are you using HVM for this instance rather than 
paravirtualisation?

> Any ideas? I'm pretty sure that the vnc setup is correct on the DomU.
> I've enabled it via 'remote administration' on YaST, xinetd is
> running, I can mod /etc/xinetd.d/vnc, etc (and I can log in anyway,
> so it must basically be working).

As Jim has mentioned previously, have you thought about using the 
qemu-vnc session itself? This is run on the Dom0 and is what 
virt-manager uses to connect to the DomU. I would suspect that a remote 
VNC connection to DomU should work without having to jump through all 
these hoops.

> I'm using a realVNC client, but SLES appears to use tightVNC. I don't
> think this is a problem. I can start a local tightVNC viewer on the
> DomU (with ssh -X), and it has exactly the same behaviour as the
> remote one (though possibly without the screensaver).

The different VNC packages won't matter - VNC is VNC... I know KDE has a 
desktop sharing option that allows you to temporarily share your 
desktop with another user via VNC. It would be interesting to see if 
this works. Do any of the usual logs (/var/log/messages etc.) provide 
any insights into what is going on?

> Another potential issue is that the relevant stuff on Google
> generally talks about using xdm, but SLES10 uses gdm by default,
> although I can't see how this could be relevant.
>
> Any thoughts? /etc/sysconfig/displaymanager currently contains (I've
> tried some variants):
>
> DISPLAYMANAGER="gdm"
> DISPLAYMANAGER_REMOTE_ACCESS="yes"
> DISPLAYMANAGER_ROOT_LOGIN_REMOTE="yes"
> DISPLAYMANAGER_STARTS_XSERVER="yes"
> DISPLAYMANAGER_XSERVER_TCP_PORT_6000_OPEN="yes"
> DISPLAYMANAGER_AUTOLOGIN="evan"
> DISPLAYMANAGER_PASSWORD_LESS_LOGIN="no"
> DISPLAYMANAGER_AD_INTEGRATION="no"
> DISPLAYMANAGER_SHUTDOWN="root"

Again, echoing Jim, this is all related to XDMCP rather than VNC. I 
guess you're just trying to get a remote login of any sort set up, 
hence it's inclusion here?

Just to satisfy my own curiousity - why is X forwarding via ssh not a 
viable solution for you?

Jon

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