Section 5.1. Linux Won t Work with All My Hardware

5.1. Linux Won't Work with All My Hardware

One common "annoyance" is the literature that warns of dire consequences if you don't record every detail of your hardware before starting the installation process. You've probably installed Linux on a variety of computers. While you may never have had a problem with hardware, trouble does happen. For this reason, some Linux vendors, including Red Hat and Novell, do test and certify hardware components as well as entire systems. They offer more extensive support if you use such hardware. Even if you're using another distribution, their certified hardware is more likely to work reliably with Linux.

5.1.1. Classifying Hardware

Any A+ certified hardware technician can list the hardware components on a computer. A Linux geek can cite the compatible components, such as the chipsets associated with a specific wireless card. He can use this information to compile the most efficient kernel for his system.

The A+ certification was developed by CompTIA, primarily as an entry-level exam for Microsoft computer hardware technicians. As someone comfortable with Linux, you know so much more about computers. The entry-level CompTIA Linux+ exam (www.comptia.org/certification/linux/) includes a significant hardware component. Other Linux certifications include those released by the Linux Professional Institute (www.lpi.org), Novell (www.novell.com/training/certinfo/), and Red Hat (www.redhat.com/training/certification/).

If you're installing Linux at home, consider whether your system has any of the common components in Table 5-1, and ensure you know at least the make and model of each component. If time is limited, focus on the components that you configure during the installation process: the size of the hard drive(s), CPU(s) type, amount of RAM, and video card chipset.

Table 5-1. Common hardware components

Component	Key information to learn	Additional information
Motherboard/BIOS	Integrated support (e.g., video)	A BIOS upgrade may add useful options.
CPU	Type (x86 [e.g., i386, i586, i686], ia-64, Itanium)	Some distributions may be built for your CPU.
RAM	Amount	Minimums vary by distribution. Some BIOSes can detect only a limited amount of RAM.
Video card	Chipset	If Linux can't detect your chipset, get the Horizontal and Vertical refresh rates.
Hard drive controller	IDE, SCSI, SATA, RAID support	SCSI and SATA can support more than the standard 4 IDE drives.
Network adapters	Chipset, revision	If Linux doesn't detect your adapter, knowing the chipset and revision level can help you find alternative drivers.
Sound	Chipset	Most have MIDI/ALSA support.
Hard drive	Size	A few drives are not supported; avoid the same IDE cable for multiple drives.
Pointing device	Mouse protocol	Most two-button mice can imitate the middle (third) button.
Keyboard	Keyboard type	Usually associated with a language.
Modem	Connection (PCI/USB/ISA)	Microsoft-dependent hardware discussed later.
Printers	Parallel/USB	Microsoft-dependent hardware discussed later.

What follows are solutions to the most common hardware annoyances, with general guidance that you can follow for unspecified hardware problems. Ideally, you should classify your systems or hardware in the following categories:

• Certified hardware by a distribution company

• Compatible hardware, as classified in one of the Linux hardware databases

• Additional Linux-compatible hardware, which requires additional research, including the Linux Hardware HOWTO

• Linux hardware in the works, with pre-release drivers

• Incompatible hardware, awaiting development

5.1.2. Certified Hardware

The first thing to check is the web site for your Linux vendor. They maintain lists of hardware and systems that they've tested. You can find Red Hat's list at http://bugzilla.redhat.com/hwcert/; Novell/SUSE currently maintains their list (English version) at http://hardwaredb.suse.de/?LANG=en_UK. If you're lucky, you're working with complete hardware systems certified for a specific distribution. Red Hat and SUSE have tested a number of complete servers, workstations, notebooks, and more. If you are installing a Linux distribution on certified hardware, you should have no problems, and you may be able to get additional support for your systems.

One implied category of certified hardware consists of computers where Linux is already preinstalled. There are a number of vendors, including big names such as HP and Dell, who sell systems where they install a major Linux distribution for you. They support their systems with the originally installed operating system. All you need to do is keep it up-to-date. However, if you add hardware or a new Linux distribution, you may be on your own.

5.1.3. Compatible Hardware

Red Hat and SUSE, among others, maintain a database of compatible hardware. Such hardware has been tested, often by employees associated with that distribution. This is known by Red Hat as "compatible hardware" and by SUSE as "ready for SUSE Linux." While distributor companies may provide limited support for such hardware, there may be interactions such as IRQ conflicts beyond their control.

Red Hat has recently changed their hardware database to focus on compatible hardware systems. As of this writing, there are very few individual hardware component compatible with Red Hat Enterprise Linux 4.

As Debian is built by volunteers, they do not have a program of certified hardware. But as with any Linux distribution, you can start your hardware checks with the Linux Hardware HOWTO, available from http://www.tldp.org/HOWTO/Hardware-HOWTO.

5.1.4. Additional Linux-Compatible Hardware

The databases provided by the Linux distributors can't keep up with the torrent of new hardware. They may not have updated their databases for the latest Linux drivers. So if you don't see your hardware on a compatibility list, don't give up! I'd look in five areas:

• Check the web site associated with your hardware. You might just find a new set of Linux drivers, ready for download. If you're lucky, you may get an RPM or DEB package that you can install directly on your system. Alternatively, if you have to compile drivers from their source code, you may need to install the Linux kernel source code for your system. Watch the Makefile associated with such source code; you may need to modify its settings.

• At other times, Linux compatibility may be there where you least expect. The chipset associated with a component may be produced by a third company.

• Third, Linux drivers for earlier versions of a component may provide partial compatibility. For example, the drivers associated with a version 1000 scanner may provide sufficient functionality if you're working with a version 1100 scanner.

• Fourth, there are developers who enjoy cloning drivers for new hardware. Just as the original Linux developers cloned the functionality of Unix, the Linux hackers of today create new source code that emulates the functionality of proprietary drivers. Sometimes hackers build the functionality with original code; other times they may build wrappers that allow use of drivers built for other operating systems. As open source developers want to share their work, their progress is usually available online. Some are organized into SourceForge groups, which are listed at http://www.sourceforge.net.

• Finally, you sometimes may be able to extract the drivers by recompiling the kernel. I describe the recompiling process in "Recompiling the Kernel" in Chapter 7.

5.1.5. Linux Hardware in the Works

Linux hackers are constantly at work on incompatible hardware. They lobby hardware vendors to release their source code. They clone drivers for desirable peripherals. The open source nature of Linux means that the development work is transparent. If you have the time, there are a multitude of projects where you can help. SourceForge is the home of a number of Linux hardware projects.

The people behind Linux distributions are often cautious. Many won't include a developmental driver until it is tested and proven to work, without causing trouble with other systems. But if you absolutely need that wireless card, that scanner, that memory stick, etc., developmental drivers may be your only choice. And if you have to compile the driver into your kernel, that's another annoyance we'll work through in "I Need to Add a Custom Kernel Module" in Chapter 7.

Any developmental software that you install may be less than complete. For example, you may need to configure a script to load the appropriate drivers the next time you boot Linux. If you want to run the script during the boot process, you can make it part of the appropriate boot script from the following table:

Distribution	Script
Debian	/etc/init.d/local
Red Hat/Fedora	/etc/rc.local
SUSE	/etc/init.d/boot.local

These files are often empty; when you add the commands of your choice, they're run automatically during the boot process. You'll actually have to create /etc/init.d/local on Debian Linux; all you need is to start the script with the first line to use the bash shell interpreter, followed by the full path to the commands you need:

 #!/bin/sh /path/to/command switch 

You'll need to make sure the command starts in the appropriate runlevels, preferably after other scripts, with the following command:

 update-rc.d local defaults 99c 

5.1.6. Incompatible Hardware

The resources of the Linux community are limited. They may not be working on the hardware that you need. There are third parties who can help, for a fee. For example, Xi Graphics' DeXtop (http://www.xinside.com) and SciTech's SNAP graphics (http://www.scitechsoft.com) provide proprietary drivers for many otherwise incompatible graphics cards. Linuxant (http://www.linuxant.com) provides a wrapper that uses Microsoft Windows driver software for network cards.

If you're brave and dedicated, you can start your own Linux hardware project. A good place to start is SourceForge, where you may ask for help from those working on related projects. Alternatively, Linux Device Drivers by Jonathan Corbet et al. (O'Reilly) is also an excellent resource, as it can help you identify starting points from related hardware.