Best of Technical Support

Our experts answer your technical questions.
New Dell Server Locks Up

At work we are about to deploy our first web site that will run under Linux, which I'm quite happy about. However, I'm having a problem with the servers and hope you can help. Our development servers are Dell 2550 machines, and our production servers are Dell 2650s. We are running Red Hat 8.0 on the equipment, which runs fine for the most part. We have had unexplained lockups, however, on all the servers, in which the console becomes locked and the machine has to be hard reset. No indication of what caused the lockup is reported in any of the log files. After searching the Dell and Red Hat forums I've found some help. Essentially, this help is to put the option noapic on the kernel command line in the grub.conf file. After doing this, the machines seem to run well. What does the noapic command option do on an SMP system? And has anyone else experienced this problem on Dell 2550/2650 machines?

—Doug Farrell,

The advanced programmable interrupt controller (APIC) replaces the standard, external interrupt controller with functionality inside the CPU itself. It supports some neat tricks such as performance counters and watchdog facilities. Normally, this support is not supposed to interfere with systems that do not have an APIC. However, in some instances this creates system lockups such as the ones you've experienced. The major implication of running in noapic mode is a performance hit, as interrupts are not handled as efficiently. For systems that are heavily interrupt-driven (this unfortunately includes those that do a lot of networking work, such as web servers) this might be measurable. Nonetheless, the benefits of SMP almost always outweigh this impact. Some load testing on your end should help you identify the maximum user loads that you can expect from your systems.

—Chad Robinson,

Belkin Wireless Card: Supported?

I am trying to get the Belkin wireless PCMCIA card to connect to a wireless access point from my laptop. I am wondering what module I should use for the PCMCIA card.

—Charles R. Fuller,

Another Linux user was kind enough to post the details of his own experience with Belkin's wireless components on his web site. This site may be helpful to you:

—Chad Robinson,

The Belkin card uses the same chipset as the Orinoco card. A simple solution is to alias the wireless device's Ethernet interface to orinoco_cs in /etc/modules.conf. If this does not work, you can find out more about the chipset with cardctl ident.

—Christopher Wingert,

Can't Boot New Install

When I attempt to boot Red Hat 7.3, I receive a message stating there is an invalid system disk. It also indicates I should replace the disk and press any key. What can I do to eliminate this problem short of reinstalling Linux?


This message typically indicates that your BIOS was unable to find a boot loader on your drive. If you installed LILO or another boot manager when you installed Linux, chances are it was not properly done, and you should double-check the parameters you used. If you didn't install a boot manager, your problem is a bit easier to identify. Either way, you should be able to use an emergency recovery disk or the original installation disk to boot your system. Then you can install the boot loader again.

—Chad Robinson,

If there is a floppy in the disk drive, remove it.

—Christopher Wingert,

How to Make XDM Come Up at Boot?

I cannot get Linux (Red Hat 7.2) to boot into the X GUI. Instead, I get a login prompt. Is there a way to edit the default init level? It also fails WINE on boot up.

—Keith Raposo,

To make sure X is correctly installed, type startx. If this works, you then can change the first non-comment line of /etc/inittab to


—Usman S. Ansari,

In your /etc/inittab there is a line that reads id:NUM:initdefault:. Change the number to your desired init level, which is 5 for an XDM login screen.

—Christopher Wingert,