Re: [gentoo-user] Is starting xdm enough to see something in X?

[Alan McKinnon]

On Friday 22 May 2009 21:19:40 Mark Knecht wrote:
> On Fri, May 22, 2009 at 12:08 PM, Matt Harrison
>
> <iwasinnamuknow@×××××××××.com> wrote:
> > Mark Knecht wrote:
> >> On Fri, May 22, 2009 at 11:49 AM, bn <brullonulla@×××××.com> wrote:
> >>> Mark Knecht ha scritto:
> >>>> Title sort of says it. I have an old machine that I'm setting up as a
> >>>> Myth server. I didn't want X on the machine but I'm having trouble so
> >>>> I emerged xdm and start it using /etc/init.d/xdm start. The  drivers
> >>>> get loaded but I get a black screen. No error message in the X log
> >>>> file.
> >>>>
> >>>> I haven't messed with X at this level before. What's the minimum test
> >>>> of X that would display a terminal or something very basic?
> >>>
> >>> Have you tried
> >>>
> >>> startx /usr/bin/xterm
> >>
> >> Yes. Same black screen. Nothing else going on. The processes show up
> >> in ps aux, X as root, xterm as me.
> >
> > I've found before that if everything seems to be running (can list X
> > processes and logs look fine) but you still don't see anything, it's
> > possible it is your monitor. I used to use a really old 15" CRT for a
> > server but it just wouldn't run X at anything over 640x480. Modern
> > monitors will at least tell you if the resolution/refresh is out of
> > limits, but older ones don't often. Try with a different monitor if that
> > one is old or suspect.
> >
> > ~Matt
>
> Good point. I'll hook the machine up to a very good monitor later today.
> Thanks.

You need to run an X-server, not the one that is displaying xdm because that 
will only run xdm and once you authenticate will launch an entirely different 
session. Either launch the failsafe session, it gives you twm on gentoo with a 
single xterm, or ditch xdm and run startx.

You can also run xinit (startx is a wrapper script around xinit that launches 
user-defined apps) and that gives you plain X without a window manager so you 
need to put at least xterm into .xinitrc

> One question about this X stuff. Is there any difference at all at the
> application level if I run an app displaying on the monitor of that
> machine, or use ssh -X -Y -C and run the app displaying on a remote
> machine?

No difference whatsoever for basic apps. X is network transparent, meaning 
that the X client reads and writes a Unix socket, TCP socket, or whatever else 
you can dream up. However, I'm sure you will find that recent fancy stuff like 
compiz and OpenGL don't work as expected.

> If there is absolutely no difference then I don't need to bother with
> this. If there is then I do. The real issue here is that Myth doesn't
> work. If I can be certain that displaying Myth apps on a remote
> screen, such as mythtv-setup or mythfrontend, is really the same then
> I'll just do that. However those apps are currently failing so I'm
> trying to eliminate issues, and possibly creating one I don't care
> about in doing that!

Running X apps locally locally tests your X libs and your X server.
Running X apps remotely tests the X libs

:-)

-- 
alan dot mckinnon at gmail dot com