I felt cursed for many months, but I finally got XFree86 configured properly. It was annoying enough that I thought I'd add my comments to the plethora of similar pages out there. I'm running Redhat Linux 5.2 on my Dell Latitude LM, which has a NeoMagic NM2070 video card. NeoMagic released drivers for this card about a year ago, so I'm no longer using a hideous kludge to get X running. However, even with the drivers, I ran into a few problems.
The first thing to note is that NeoMagic support is only in XFree86 versions 3.3.3 and higher. Redhat 5.2 probably comes with a higher version now, but if you're starting from SIPB's Redhat-Athena install (for MIT folks), you'll need to upgrade your version of XFree86. I had the most luck using version 3.3.3. You could get the RPMs from Redhat, or install tarballs directly from ftp://ftp.xfree86.org/pub/XFree86/3.3.3/binaries/Linux-ix86-glibc/. There are good instructions from the Linux Documentation Project.
I ran XF86Setup, which worked well for configuring my mouse, keyboard, and such, but the resulting config file didn't let me use resolutions higher than 640x480. That was sort of annoying, since the LCD is 800x600 and anything else looks stretched oddly. So, after a lot of playing with it, I managed to get this XF86Config file, which lets you get 800x600 resolution and 8 bits per pixel.
Unfortunately, I can't get 16bpp, since the computer has only 896K of video memory. Back when I used a kludged driver and config file, it ran out of video memory very nicely; I could use 16bpp but it wouldn't draw the bottom 30 lines of the screen. If anyone knows how to make the officially-supported NM2070 stuff do the same thing, I'm curious.
As usual, nothing I've recommended is guaranteed to work. It's better to play with this on your own for a while, instead of just copying the config file. You may want to change the keyboard, pointer, etc sections; I recommend running XF86Setup or the equivalent, and using the parts of that file other than the monitor/display related ones. Some of this may be useful for other NeoMagic chipsets, as well, with a few modifications.
Liana Lareau (fyfer@mit.edu)