I ususally give up on this but here is the cure (at least for my system). I am running lilo, however I expect it should work with grub also.
Add the following to your lilo.conf
append=”iommu=65534,noagp,soft”
Run lilo -L, and reboot. You should now be able to see 4gb memory and run xorg correctly!
I have installed Ubuntu 8.04 – amd64 version. Here are some of my impressions.
Easy installation, one cd/network install very quick. Debian based- If your familiar with Debian, Ubuntu is an evolved version. It is virtually identical to Debian with some eye candy and improved 3d setup. You also have the advantage of the latest kernel/libraries that are available to new distros. Firefox 3 (beta 5) is the default browser. I find it very stable. Openjava and flash work fine as well as all the mplayerplug-in’s necessary to play movie trailers, etc. Pulseaudio seems to be transparent. I have noticed no problem with either software compatablility or other issues. Repositories seem to be very complete. Nvidia support works out of the box. I opted to try the new Nvidia beta driver so I did a manual install which worked with no issues. Support forums are excellent. I found answers to all but a couple of questions there, including how to update the browser with the latest plugins (which worked).
Problems- I had few. One major problem that I also had with Debian was an annoying hard disk error message. I previously found the fix (while using Debian) for my hardware. I needed to add:noapic nolapic as a kernel boot parameter (lilo in my case) which eliminated the error. I did not like the xterm looks (compared to Fedora/Centos). After a little experimenting, I was able to use the Centos configuration by replacing the /etc/X11/Xresources folder with the Xresources file from my Centos installation. This produces the identical xterm look you have in Fedora/Centos. One other obvervation. I am using 2gb ram with this install. 4gb ram will not function correctly with this hardware. It will boot and bring up X however, the cursor is a large grainy block. There are several suggested cures for this however, I have not found one that works for my configuration. I can use the same hardware with 4gb ram and Centos 5.1 (64 bit) without problems. I am guessing Centos has patched the kernel to eliminate the bug. One other obversation. I like a large virtual screen. Apparently you cannot do this with gdm and Ubuntu (unlike Debian). Instead, I do not run gdm. I simply boot to a console terminal and use a runx script (startx — -depth 24 -dpi 96).
To get your best looking fonts while using the Nvidia driver under Xorg.. try this:
xdpyinfo | grep resol
If the result is not 96×96, then add the following line to xorg.conf in the “Device” section:
Option “DPI” “96 x 96″
Restart Xorg and check again with xdpyinfo. It should report 96×96 and your fonts should be improved!
After testing Ubuntu, Debian, Fedora 8, Centos 5.1, Slackware 12 and a few others, I have concluded that running more than 2gb memory on the desktop is very finicky. Centos and Fedora seem to do it well in the 64 bit mode. The Debian variants do not fare as well except for Debian “etch” which did function correctly in the i386 mode with the bigmem i686 kernel.
I conclude that the hardware detection mechanisms (udev, hot plug, etc) have a lot to do with your success. I have only experimented with a couple of motherboards. The chipset/bios is also a factor I am sure.
Truth is you do not really need 4gb memory on a desktop box. It is just an experiment since I had the memory on hand.
Seems my previous post is not always correct. The better and more reliable way to update nvidia drivers is to run the”official” nvidia driver script, compile and install the driver on your system. Their is one caveat, after you reboot, xorg will probably not start. The culprit is the /init.d/nvidia-glx script, you need to defeat this by either removing the script or chmod it so it won’t execute.
You newly installed nvidia drivers (installed the Nvidia way) should now survive a reboot .