Now, you must be convinced of how wonderful Linux is and of all thegreat things that it can do for you. However, before you rush out andinstall the software, you need to be aware of its hardwarerequirements and limitations.
Keep in mind that Linux was developed by its users. This means, forthe most part, that the hardware supported by Linux isthat which users and developers actually have access to. As itturns out, most of the popular hardware and peripherals for 80x86systems are supported (in fact, Linux probably supports more hardwarethan any commercial implementation ofUnix). However, some of the more obscure andesoteric devices, as well as those with proprietary drivers for whichthe manufacturers do not easily make the specifications available,aren’t supported yet. As time goes on, a wider rangeof hardware will be supported, so if your favorite devices aren’t listedhere, chances are that support for them is forthcoming.
Another drawback for hardware support under Linux is that manycompanies have decided to keep the hardware interface proprietary. Theupshot of this is that volunteer Linux developers simply can’t writedrivers for those devices (if they could, those drivers would be ownedby the company that owned the interface, which would violate theGPL). The companies that maintain proprietaryinterfaces write their own drivers for operating systems, such as Microsoft Windows; the end user (that’syou) never needs to know about the interface. Unfortunately, this doesnot allow Linux developers to write drivers for those devices.
Little can be done about the situation. In some cases,programmers have attempted to write hackish drivers based on assumptionsabout the interface. In other cases, developers work with the companyin question and attempt to obtaininformation about the device interface,with varying degrees of success.
Linux includes a number of laptop-specific features, such as PCMCIA(or “PC Card”) support and APM. The PCMCIA Tools package for Linuxincludes drivers for many PCMCIA devices, including modems, Ethernetcards, and SCSI adaptors; the PCMCIA HOWTO is the documentthat you need to get started.
APM allows the kernel to keep track of the laptop’s battery power andperform certain actions (such as an automated shutdown) when power islow; it also allows the CPU to go into “low power” mode when not inuse. This is easy to configure as a kernel option. Various toolsinteract with APM, such as apm (which displaysinformation on battery status) and apmd (which logsbattery status and can be used to trigger power events). These shouldbe included with most Linux distributions.
In the following sections, we’ll attempt to summarize the hardwarerequirements for Linux. The Linux Hardware HOWTO(see Section 1.10 later in this chapter for an explanation ofHOWTOs) contains a more complete listing ofhardware supported by Linux.
Note
A good deal of hardwaresupport for Linux is currently in the development stage. Some distributionsmay or may not support these experimental features. This section primarilylists hardware that has been supported for some time and is known to bestable. When in doubt, consult the documentation for the distribution ofLinux you are using (see Section 2.1 in Chapter 2) for more information on Linux distributions).
Another caveat to watch out for: occasionally hardware supplierswill substitute the latest version of a system component (such as anetwork board) regardless of what you originally ordered. When indoubt, be sure to check the particular hardware that you have.
Linux currently supports systems with an Intel 80386, 80486, Pentium,Pentium Pro, Pentium II, and Pentium III CPU.This includes all variations onthis CPU type, such as the 386SX, 486SX, 486DX, and486DX2. Non-Intel “clones,” such as AMDand Cyrix processors, work with Linux as well.
Linux has been ported to a number of non-Intel architectures. Theseinclude the Alpha AXP, MIPS,PowerPC, SPARC, and Motorola 68K. At the time ofthis writing, some of these ports are more mature than others.Red Hat ships both SPARC and Alpha versions of its distributionin addition to the Intel x86 versions, as does Debian. SuSE has anAlpha version at well, and Debian even provides a Motorola 68Kdistribution.(See Appendix E.) In this book,we concentrate on the version of Linux for Intel x86 systems. Apartfrom hardware requirements and basicinstallation you should find that the majority of this book is just asrelevant to ports of Linux to other architectures.
If you have an older 80386 or 80486SX, you may also wish to use a mathcoprocessor, although one isn’t required (the Linux kernel can doFPU emulation if you do not have a mathcoprocessor). All standard FPU couplings aresupported, such as IIT, Cyrix FasMath, and Intel coprocessors.
The system motherboard must use ISA,EISA, PCI, orMicroChannel (MCA) busarchitecture. These terms define how the system interfaces withperipherals and other components on the main bus.
Systems that use a local bus architecture (for faster video and diskaccess) are supported as well. It’s suggested that you have a standardlocal bus architecture, such as the VESA Local Bus(VLB).
Linux requires very little memory to run compared to other advancedoperating systems. You should have at the very least 8 MB ofRAM; however, it’s strongly suggested that you haveat least 16 MB. The more memory you have, the faster the system will run.
Linux can support the full32-bit address range of the 80x86; in other words, it will utilizeall of your RAM automatically. Amounts of RAM greater than 64 MB need a boot-time parameter.
Linux will run happily with only 8 MB of RAM,including all of the bells and whistles such as the X Window System,Emacs, and so on. However, having more memory is almost as importantas havinga faster processor. Sixteen megabytes is just enough forpersonal use; 32 MB or more may be needed if you are expecting a heavyuser load on the system. Linux systems can, of course support systemswith very large amounts of memory—including 1 GB or more.
Most Linux users allocate a portion of their hard drive as swap space,which is used as virtual RAM. Even if you have agreat deal of physical RAM in your machine, you maywish to use swap space. While swap space is no replacement for actualphysical RAM, it allows your system to runlarger applications by swapping out inactive portions of code to disk.The amount of swap space you should allocate depends on severalfactors; we’ll come back to this question in Section 2.2.3 in Chapter 2.
You do not need a hard drive to run Linux, in fact; you can run a minimalsystem completely from floppy! However, using Linux with a hard disk isthe standard way of doing things.Linux should support allMFM, RLL, andIDE controllers. Most, but not all,ESDI controllers are supported—only thosewhich do ST506 hardware emulation.
The general rule for non-SCSI hard drive and floppycontrollers is that if you can access the drive fromWindows or another operating system, you should beable to access it from Linux.
Linux also supports a number of popular SCSI drivecontrollers, although support for SCSI is morelimited because of the wide range of controller interfacestandards. Supported SCSI controllers include theAdaptec AHA2940, AHA3940AHA1542B, AHA1542C,AHA1742A (BIOS Version 1.34),AHA1522, AHA1740(SCSI-2 controller, BIOS Version1.34 inEnhanced mode); Future Domain 1680, TMC-850,TMC-950; Seagate ST-02; UltraStorSCSI; and Western DigitalWD7000FASST. Clones that are based on these cardsshould work as well. This list is just a sampling; the number ofsupported SCSI drives is too great to enumeratehere.
Of course, to install Linux, you’ll needto have some free space on your hard drive. Linux willsupport multiple hard drives in the same machine; you can allocatespace for Linux across multiple drives if necessary.
The amount of hard drive space you will require depends greatly onyour needs and the amount of software you’re installing. Linux isrelatively small as Unix implementations go; youcould run a complete system in 10 to 20 MB of space on yourdrive. However, if you want to have room for expansion, and for largerpackages, such as the X Window System, you need more space. If you planto allow multiple users to use the machine, you need to allocatestorage for their files.
In addition, you’ll more than likely want toallocate swap space on your hard drive to be used as virtualRAM. We will discuss the details of installingand using swap space in Section 6.2 in Chapter 6.
Each distribution of Linux comes with some literature thatshould help you to gauge the precise amount of storage requireddepending on the amount of software you plan to install. You can run aminimal system with less than 20 MB; a complete system with all of thebells and whistles in 300 MB or less; and a very large system with roomfor many users and space for future expansion in 1 GB. Again,these figures are meant only as a ballparkapproximation; you must look at your own needs and goals in orderto determine your specific storage requirements.
Linux supports all standard Hercules, CGA,EGA, VGA, IBMmonochrome, and Super VGA video cards and monitorsfor the default text-based interface. In general, if the video cardand monitor coupling works under another operating system such asWindows, it should work fine with Linux. OriginalIBM CGA cards suffer from “snow” underLinux, which is unpleasant. (If you have one of these cards, you mightwant to donate it to a museum anyway.)
Graphical environments, such as the X Window System, have video hardwarerequirements of their own. Instead of listing these requirements here, we relegate the discussion to Section 10.2 in Chapter 10. In short, to run the X Window System onyour Linux machine, you need one of the video cards listed inthat section. The good news is that nearly all graphics boards (includinghigh-end ones) are supported.
The previous sections described the hardware required to run a Linuxsystem. However, most users have a number of “optional”devices such as tape and CD-ROM storage, soundboards, and so on, and are interested in whether or not this hardwareis supported by Linux. Read on.
For the most part, you will be using a mouse only under a graphicalenvironment, such as the X Window System. However, several Linuxapplications not associated with a graphics environment also use amouse.
Linux supports all standard serial mice, including Logitech, MMseries, Mouseman, Microsoft (two-button), and Mouse Systems(three-button). Linux also supports Microsoft, Logitech, andATIXL busmice. The PS/2 mouse interface issupported as well.
All other pointing devices, such as trackballs, which emulate themice just listed, should work as well.
Most CD-ROM drives sold today use the near-universalIDE/ATAPI CD-ROM standard, which is fully supportedunder Linux. Many CD-ROM drives usethe SCSI interface instead, and as long as youhave a SCSI adaptorsupported by Linux, your CD-ROM drive shouldwork.
Linux supports the standard ISO-9660 filesystem forCD-ROMs, including the Microsoft filename extensions.
In addition to the CD-ROM drives, Linuxsupports a number of CD-R andCD-RW drives that you can use to make your ownCD-ROMs.
Various DVD-ROM drives are supported in Linux kernel version 2.2; however,filesystems allowing direct access to the DVD contents are not yetincluded. By the time you read this, we expect them to be fully supported.
There areseveral types of tape drives available on the market. Many usethe SCSI interface, all of which should besupported by Linux. QIC-02 and so-called“floppy tape” devices (which hang off of the floppy controller)are well-supported, as are various kinds of removable storage media, such asDAT, and the Iomega ZIP drive.
Linux supports the complete range ofparallel printers. If you are able to access your printer via theparallel port from Windows or another operatingsystem, you should be able to access it from Linux as well. The Linuxprinting software consists of the Unix standardlp and lpr software. Thissoftware also allows you to print remotely via the network, if youhave one available.
As withprinter support, Linux supports the full range of serial modems, bothinternal and external. If your modem is accessible from anotheroperating system on the same machine, it is likely that you can accessit from Linux with no difficulty. However, Linux does not supportso-called “Winmodems,” a kludge where the operating system has totake over many of the modem’s tasks. In addition, some internal PCImodems are not supported.
Linux supports nearly every Ethernet and Fast Ethernet card availablefor the PC platform, and those that are not supported are more thanlikely being worked on as this is being written.Linux kernel Version 2.2 includes drivers for a number of high-performance networkinterfaces as well, including the Packet Engines G-NIC, Alteon AceNIC, and3Com 3C985 PCI Gigabit Ethernet adaptors. A number of token ring andATM interface cards are supported, as are various System Area Networks,such as Myricom’s Myrinet.
