Video driver falls back to VESA

[mecho]

Since yesterday when I boot knoppix 6.2 X starts with intel driver, show half black screen and half my desktop horizontally divided, then X restarts using vesa driver. No change has been done to the system.I only used the usb stick on another laptop and since then this occurs.
Does anyone have any idea what could have made this happen. I have booted successfully on other machines a few times before without any problems afterwards

[krishna.murphy]

Since yesterday when I boot knoppix 6.2 X starts with intel driver, show half black screen and half my desktop horizontally divided, then X restarts using vesa driver. No change has been done to the system.I only used the usb stick on another laptop and since then this occurs.
Does anyone have any idea what could have made this happen. I have booted successfully on other machines a few times before without any problems afterwards

That sounds like a video-detection issue. I've noticed that, with a persistent store, Knoppix will remember something of the setup from previous boots. I think the solution would be to use a boot code to force the driver back to what worked before, i.e. intel-whatever. Alternatively, you might use

knoppix xmodule=svga screen=1024x768

This should work on most systems, I think - and then perhaps it will auto-correct itself on reboot. FWIW...

Ciao!
Krishna

[mecho]

Thank you Krishna - that worked. I booted using knoppix xmodule=intel and the second boot was just fine with no codes. Thanks a lot, I am relieved . I did not back up lately and were going to loose a lot of changes if it wasn't for your help
It would be interesting to know, what exactly does knoppix remember, so it might be cleaned manually

[mecho]

Just to clarify the issue. Knoppix writes the last used video driver in /etc/sysconfig/xserver.
Any subsequent boot of Knoppix will be with the last successfully used video driver, unless a boot command xmodule= is specified or /etc/sysconfig/xserver is cleaned or deleted

[utu]

@mecho

Can you compare xorg.conf before & after the changes you observe?
Maybe changes are accumulated there. Just a thought.

[mecho]

If you manually set "device" section in xorg with say "intel" driver, /etc/sysconfig/xserver has XMODULE="fbdev" and you restart Knoppix will boot with fbdev driver. 6.2.1 has an option to preserve xorg.conf if you manually clear the first 2 lines, but I don't really like that option. I prefer to edit mkxorgconfig then preserving xorg.conf

[utu]

Is there a cheatcode that says probe for video, rather than use last configuration?

[mecho]

To make it more understandable. This is what happens. I used my Knoppix flash on another laptop with Radeon video. Knoppix did not manage to load the Radeon driver properly, so it loaded Vesa. Then when I went back to my laptop, Knoppix booted with Vesa driver - it didn't even make an effort to load the Intel driver even though it works flawlessly. It is because there was already an entry in /etc/sysconfig/xserver saying XMODULE="vesa" and vesa works well on any hardware, so it just started using Vesa on every boot, untill Krishna told me to use cheat code to force the Intel driver. Once you boot successfully with some driver it just sticks there untill you change it.

And yes, the code is to simply force your known working driver using xmodule= one time, after that every boot is good

[utu]

As a refinement, since you are satisfied with vesa as a universal driver after the framebuffer phase,
I suggest making the earlier phase just a scan to select a fb appropriate to the video hardware.
I've seen this in Ubuntu 10.04. Seems like one size doesn't fit all in frame buffers in Ubuntu, anyway.

In Ubuntu, one of the options is to suffer thru the framebuffer phase which doesn't last too long;
the subsequent X-session phase proceeds ok, then a brief fb phase on shut-down. I spent a month
on this because the initial Ubuntu 10.04 opted to not include SIS video's fb, which it turns out can
be made to work just as well as what those from what they call 'the big three' video suppliers.

[utu]

What I'm suggesting is a cheatcode, which may not now exist,
which allows you to retain most of your .img, but selectively
retest some of the hardware, not all of it.

If you always go from machine to machine you need something
like this. Krishna's work-around is ok if you know what video
to fall back on. If you didn't, you'd have to test somehow.

Promiscuity has its pitfalls.