Disable 3D (dri) in Lucid?

Section "Module"
        Disable "dri"
EndSection

Add that to your xorg.conf

may help

Thanks for the reply. I have tried that and the same thing happens according to the xorg log. The system decides to switch dri on anyway, Here are the relevant lines for the module loading

(II) "extmod" will be loaded. This was enabled by default and also specified in the config file.
(II) "dbe" will be loaded. This was enabled by default and also specified in the config file.
(II) "glx" will be loaded. This was enabled by default and also specified in the config file.
(II) "record" will be loaded. This was enabled by default and also specified in the config file.
(II) "dri" will be loaded by default.
(II) "dri2" will be loaded by default.

Notice that all the other modules say "and also specified in the config file" while the dri ones do not.
What does loaded by default here mean I wonder?

you could blacklist the dri module, may help. Bit hacky but should work. If you run:

lsmod | less

Do you see dri there, if so, blacklist it good

Thanks for your replies. I mistyped the disable line before.
Now with both dri and dri2 disabled the X server does not start and an error message comes up regarding kernel modesetting. I tried restarting X in the fallback menu and it works but dri is enabled. Here are the relevant lines in the log:

(WW) "dri" will not be loaded unless you've specified it to be loaded elsewhere.
(WW) "dri2" will not be loaded unless you've specified it to be loaded elsewhere.
(II) "extmod" will be loaded. This was enabled by default and also specified in the config file.
(II) "dbe" will be loaded. This was enabled by default and also specified in the config file.
(II) "glx" will be loaded. This was enabled by default and also specified in the config file.
(II) "record" will be loaded. This was enabled by default and also specified in the config file.
(II) "dri" will be loaded even though the default is to disable it.
(II) "dri2" will be loaded even though the default is to disable it.

And: later

(EE) intel(0): No kernel modesetting driver detected.
(II) UnloadModule: "intel"
(EE) Screen(s) found, but none have a usable configuration.

Fatal server error:
no screens found

That last modesetting message is what comes up at the initial boot.

The lsmod reveals no dri modules. Is dri an xorg rather than kernel module?

According to Bug #317457
Option "DRI" "False"

https://wiki.ubuntu.com/X/Troubleshooting/IntelPerformance
https://wiki.ubuntu.com/X/KernelModeSetting

Workaround E: Disable DRI
"DRI" "off"
https://wiki.ubuntu.com/X/Bugs/Lucidi8xxFreezes

Thanks for the reply.
These option do not switch off dri. It may be that Kernelmodesetting is always switching dri on
no matter what is specified in xorg.conf. I switched Kernelmodesetting off but then X fails to start and I get a black screen. The error lines in the log say that no kernelmodesetting driver detected and then that the intel module has been unloaded.

Yep, as the freezes_page says,
<Workaround G: Re-enable KMS and disable DRI>
it's just a workaround and no final solution.
Remember to update initramfs and grub after any changes.
Another blank_screen_workaround.
http://ubuntu-tutorials.com/2010/05/06/ubuntu-10-04-lucid-blank-screen-at-startup-workaround/
Anyway I'd remove the quiet_splash_thing.

I removed the quiet and splash option on boot and inserted i915.modeset=0 . The system boots fine with much text visible (unlike with quiet and splash case) until X starts when it starts flashing and then goes to a blank screen. The only thing I can think of is that the xorg.conf file is faulty in some way. Is there a way of generating one guaranteed to work?

Sure, boot to root recovery mode and run:

mv /etc/x11/xorg.conf /etc/x11/xorg.conf_old; Xorg --configure

This will give you a vanilla xorg.conf file but will retain the original in the form of /etc/x11/xorg.conf_old

HTH

OK tried that and no go. When I ran Xorg -configure
there was an (EE) comment:

intel(0) no kernel modesetting driver available

I tried running X with this file and a blank screen occurred.
I also tried the reboot passing i915.modeset=0 and again an almost blank screen.
This time though there were a few dots on the screen.

Seems as if running with xorg.conf is really very difficult on this system....

A disabled dri doesn't prevent Xserver from working.
http://wiki.debian.org/XStrikeForce/FAQ#nodrinotfatal
http://wiki.debian.org/Xorg

Regarding KMS Wiki and if 'Workaround E' (Lucid freeze) doesn't solve the issue consider to report a bug against linux incl. tag "xorg-needs-kernel-fix".

## Background.
According to
http://wiki.x.org/wiki/XorgConfModulesSection
# direct rendering infrastructure which makes opengl go fast
   Load "dri"

#2 The DRM enforces the DRI security policy for access to the graphics hardware.
http://dri.sourceforge.net/doc/drm_low_level.html

Kernel module drm.
http://www.mjmwired.net/kernel/Documentation/kernel-parameters.txt#46
#46 DRM Direct Rendering Management support is enabled

lsmod
e.g. output:
drm 199204 5 video_driver,ttm,drm_kms_helper
drm_kms_helper 30742 1 video_driver

Dependencies for each kernel version are in:
/lib/module/<Kernel_version>/modules.dep

modinfo drm
## The relevant line is empty here.
depends:

## modprobe deals with dependencies, loads and unloads modules.
modprobe --show-depends drm
insmod /lib/modules/2.6.32-24-generic/kernel/drivers/gpu/drm/drm.ko

modprobe --show-depends drm_kms_helper
insmod /lib/modules/2.6.32-24-generic/kernel/drivers/gpu/drm/drm.ko
insmod /lib/modules/2.6.32-24-generic/kernel/drivers/gpu/drm/drm_kms_helper.ko

I found out that in Xorg version 2.10 and above that kms is mandatory. It appears that
options are passed to kms through the boot line i.e. like kernel options. Unfortunately
the possible options are not listed anywhere. I assume that a switch off 3d option
should be possible. Anyone know if there is such an option?

You could blacklist the intel driver and just use vesa which has no 3D