XF86Config - Part IX

XF86Config - Part IX

We’re into the third week of breaking apart the XF86Config file, far and away the longest we’ve spent on any single element of your Linux system. It is a critical element to most folks, so the time an detail is justified. Hopefully, it’s been useful. Today, we’ll look at the Monitor section of XF86Config.

Identifier subsection:
This subsection does more than merely identify your monitor (or monitors) in a way that’s easy to read. It establishes the name you’ll use for a particular monitor in the Screens section of XF86Config. The subsection contains an identification string, a VendorName sub and a ModelName sub. As I’ve noted earlier, XF86Config-4 has simplified this process quite a lot. The Identifier subsection is one of the areas that’s undergone a great change in recent months.

HorizSync subsection:
This subsection defines the horizontal sync rate of your monitor. If you have your monitor documentation handy, setting this section should be no problem. If you’ve lost the original documentation, a safe setting for most monitors is 31 - 38 Hz.

VertRefresh subsection:
This is the definition for the vertical refresh rate of your monitor. Put another way, this subsection defines how often your monitor refreshes from top to bottom. As with the NorizSync subsection, you should check your monitor documentation for the acceptable vertical refresh rates. If no documentation exists, you should be safe with a range of 50 - 90 Hz.

Modeline subsection:
Aside from being the most important Monitor subsection, the Modeline subsection is probably the most cluttered section of your XF86Config file. That’s actually a good thing. Most XF86Config files are installed with nearly all possible modes included in this subsection. A typical chunk of the Modeline subsection contains a commented summary of that particular mode (denoted with the # sign) in the first line. In the second line is a series of code blocks. The first is the selected resolution (”1280×1024″, for example). The second is a dot-clock setting. The next section of the line contains all the horizontal settings including, in order, the horizontal resolution, horizontal sync start, horizontal sync end, and horizontal total. The final block on the line contains the vertical settings, in a format mirroring the horizontal settings. As I’ve noted, these are pre-built into the XF86Config file, so you may never have to change them.

If you hadn’t given it much thought before now, you’re starting to understand the complexity of your X Window server. We’ll take a look tomorrow at another crucial piece of the GUI pie - the Device section in the XF86Config file.