Screen Resolution

Paul M. Bucalo ubuntuser at pmbservices.com
Tue May 31 01:42:06 UTC 2005


On Mon, 2005-05-30 at 18:39 -0400, Gimmie an A wrote:
> I've had the same problem, but when I try to run that commad, after it
> gets to the part where It asks something about DRI (I'm a complete
> newbie, so I have no idea what half the stuff asked to me meant in
> that. I left them as default), it quits Gnome, and goes to the command
> prompt. Please help!

I'll admit that it took me a long time to gather information and
experience in manually configuring my video cards under Linux. For a
newbie, I suppose it must be daunting when it never had to be done under
Windows. All I can do for you, without literally reproducing a summary
of every screen of information from the configuring wizard, is to give
you some pointers as to how I would do it for one of my boxes that had
the same problem. You will have to interpret what to do for your own
situation based on this information. Trial and error, or better yet, a
friend who knows more that you can have come over and take over for you,
is how many of have learned when the research is there but doesn't click
within our brains.

If you are not able to load X at all, it's easier. Login as root or use
sudo: 'dpkg-reconfigure xserver-xorg'. If already in X, switch to
another console (CTRL-ALT-F2).

When you come to the screen that asked what level of configuration you
wish to use, pick 'Advanced'. This will demand more knowledge of you,
but it allows you to precisely deal with your problem.

Here are the key areas that you must deal with:

1) When it asks for the name of the video card, it will default to
Generic Display Adapter. Change this to The name of your video card. It
helps to have the appropriate name so you can better track what you are
looking at in xorg.conf.

2) When the table of choices for your display adapter comes up, you need
to pick the 'best' one for your hardware. What's 'best' depends upon
your display adapter. For instance, I have one box that uses a generic
RIVA TNT2 and another that uses a NVidia GForce2 MX. The best choice for
either at this point is 'nv', for NVidia. If you don't see a good
choice, you will need to look at the chipset on the card or do some
research on the Web (or look at your card's manual, if you still have
it) to find out what drives it. You really can't go any further until
you know what drives your display card.

3) The next question deals with the display memory. Remember to take the
number of MBytes and multiply by 1,024. That will be the number of
Kilobytes your display uses. So, on the RIVA TNT2, it would be 32,768 KB
(32 MB). What I have found is that on this particular card, no Linux
distro I have ever tried (and I have tried many!) has ever detected more
than 2 MB. If this happened to you, that would account for the low
resolution. Ubuntu defaults to 24-bit color depth at the expense of
resolution when the memory isn't there to have both.

4) Next you pick the display resolution for X. I have nothing larger
than a 17" monitor and as small as 14", so I choose 1024x768
exclusively. If you want more, make sure that your display card and
monitor can actually do it. I uncheck '800x600' and '640x480' leaving
only '1024x768'. It's what I want and all that I will settle for. You
can leave the lower values in, but be aware that if you are successful,
you may get one of those lower values. I would rather have X fail and
notify me that I need to tweak it further to get what I want. Just me.

5) The monitor settings are extremely critical. If you mess this up, err
on the high side, you can fry your monitor. Make sure to have the
correct horizontal and vertical scan frequencies of your monitor. You
can get these off the Web (using elinks in your console or one another
PC with a GUI if yu are not in X) or from your monitor's manual. Chances
are your system has guessed wrong or wrong enough to foil success and
why you are either not able to get X running or too small a resolution.
Make sure to enter the correct numbers in the correct place. It's not
hard to mix up the numbers, horizontal for vertical, and vice versa.
Vertical refresh is the killer, if too high. The numbers need to be a
range, like '30-48' or '50-120'. 

6) The next setting asked for is color depth. Keep in mind that the
display values of resolution, color depth and vertical scan rate are all
on a side of a three-sided balance. If you increase one, the others have
to decrease accordingly to make up the difference. If you have at least
4 MB of VRAM, you can expect to be able to get 1024x768, 24-bit color
and at least 70 MHz refresh rate. Up any one and the others must go down
in value. More memory will give you better vales all around. I have been
able to get Ubuntu 5.04 to bring up a Gnome desktop with a Jaton TV-67
display adapter having only 2 MB of VRAM. I can get a max of 1024x768,
15-bit color and 70 MHz refresh rate. :0)

7) The next settings are on the mouse. If you have a two button PS/2
wheelmouse, your choice should be '/dev/psaux', 'ImPS2', and that you
don't want Emulate3Buttons activated. Change your settings according to
the type of mouse you have.

The rest is pretty much default stuff. If you are using the default
settings of whatever  keyboard and country settings is present, you just
keep pressing ENTER all the way through, otherwise adjust accordingly.
Don't worry about 'DRI', or anything you don't understand outside of
display adapter, monitor and mouse settings. When you are done, let it
overwrite your xorg.conf. As soon as you get X running, make sure to
make a backup copy of xorg.conf *even if everything is not totally
correct*. This is important, as it's really helpful to have something
that is partially working to look at if you are stuck with manual
tweaking. 

Run X from your console, 'startx', and see what happens. If you get an
error that no screens could be found, you have picked a default color
depth not possible for the screen resolution you picked, or your monitor
can't use the frequencies that X is trying to invoke. Once you have X
running from the console, you can try a reboot and see if gdm brings up
X.

Sorry for the long post. I do hope it helps you or someone else out. 

Paul





More information about the ubuntu-users mailing list