Linux FAQ - Section 1
Introduction and General Information

• Q1.1. What is Linux ?
• Q1.2. What software does it support ?
• Q1.3. Does it run on my computer ? What hardware is supported ?
• Q1.4. What ports to other processors are there ?
• Q1.5. How much hard disk space does Linux need ?
• Q1.6. Is Linux PD ? Copyrighted ?

It has all the features you would expect in a modern fully-fledged Unix, including true multitasking, virtual memory, shared libraries, demand loading, shared copy-on-write executables, proper memory management and TCP/IP networking.

It runs mainly on 386/486/586-based PCs, using the hardware facilities of the 386 processor family (TSS segments et al) to implement these features. Ports to other architectures are underway [Q1.4 `What ports to other processors are there ?'].

See the Linux INFO-SHEET [Q2.1 `Where can I get the HOWTOs and other documentation ?'] for more details.

The Linux kernel is distributed under the GNU General Public License - see Q1.6 `Is Linux PD ? Copyrighted ?' for more details.

Question 1.2. What software does it support ?

There is a DOS emulator (look on tsx-11.mit.edu in /pub/linux/ALPHA/dosemu) which can run DOS itself and some (but not all) DOS applications. I'm told that it can now run Windows 3.1 in Enhanced Mode.

An iBCS2 (Intel Binary Compatibility Standard) emulator for SVR4 ELF and SVR3.2 COFF binaries is at a fairly advanced stage of development. See the file /pub/linux/BETA/ibcs2/README on tsx-11.mit.edu.

Work is progressing on an emulator for Microsoft Windows binaries [Q3.6 `Can I run Microsoft Windows programs under Linux ?']; alternatively, I'm told that the DOS emulator team have been having some success getting MS Windows to run inside dosemu - there will be an announcement if and when they get it working.

For more information see the INFO-SHEET, which is one of the the HOWTOs [Q2.1 `Where can I get the HOWTOs and other documentation ?']. See also Q5.1 `How do I port XXX to Linux ?'.

Some companies have commercial software available, including Motif. They announce their availability in comp.os.linux.announce --- try searching the archives [Q2.9 `Are the newsgroups archived anywhere ?'].

Question 1.3. Does it run on my computer ? What hardware is supported ?

VESA local bus and PCI are both supported.

There are problems with machines using MCA (IBM's proprietary bus), mainly to do with the hard disk controller. There is a developers' release for PS/2 ESDI drives on invaders.dcrl.nd.edu in /pub/misc/linux. Certain kinds of SCSI controllers also work, I understand. Work is in progress to create a suitable version of the Slackware distribution. I'm afraid I don't have any further details; you could try asking Arindam Banerji axb@defender.dcrl.nd.edu.

Linux runs on 386 family based laptops, with X on most of them. There is a relevant Web page at http://www.cs.utexas.edu/users/kharker/linux-laptop/.

For details of exactly which PC's, video cards, disk controllers, etc. work see the INFO-SHEET and the Hardware HOWTO [Q2.1 `Where can I get the HOWTOs and other documentation ?'].

There is a port of Linux to the 8086, known as the Embeddable Linux Kernel Subset (ELKS). This is a 16-bit subset of the Linux kernel which will mainly be used for embedded systems. See http://www.linux.org.uk/Linux8086.html for more information. Linux will never run fully on an 8086 or '286, because it requires task-switching and memory management facilities not found on these processors.

Recent versions of Linux (1.3.35 and later) do support multiprocessor machines, though this is still rather less stable than one would hope.

Question 1.4. What ports to other processors are there ?

There used to be a project to port Linux too 68K-based Macintoshes, but its FTP site disappeared recently and the project appears to be dead.

There is a port to the PowerPC. As of the 7th of July it is rather fragmentary and cannot recompile itself, and only supports Motorola 1603 boards. Work on Motorola Ultra, PowerStack, RS/6000 and NuBus machines continues. If you wish to contribute to the project join the linux-ppc mailing list [Q2.8 `What mailing lists are there ?']. There is a FAQ on liber.stanford.edu in /pub/linuxppc/linux-ppc-FAQ or on the WWW at http://liber.stanford.edu/linuxppc/linux-ppc-FAQ.html.

Apple and the OSF are working on a PowerPC port of Linux based on the OSF Mach microkernel. See http://mklinux.apple.com/.

There is a port to the 64-bit DEC Alpha/AXP. See http://www.azstarnet.com/~axplinux/. Again, there is a mailing list at vger.rutgers.edu.

Ralf Baechle is working on a port to the MIPS, initially for the R4600 on Deskstation Tyne machines. The Linux/MIPS FAQ is available on the WWW and in the MIPS port area on ftp.waldorf-gmbh.de in /pub/linux/mips. There is also a MIPS channel on the Linux Activists mailserver and a linux-mips mailing list [Q2.8 `What mailing lists are there ?']. Interested people may mail their questions and offers of assistance to linux@waldorf-gmbh.de.

There are currently two ports of Linux to the ARM family of processors ongoing; one of these is to the ARM3 as fitted to the Acorn A5000, and includes I/O drivers for the 82710/11 as appropriate, and the other is to the ARM610 as fitted to the Acorn Risc PC. The Risc PC port is currently in its early to middle stages, owing to the need to rewrite much of the memory handling. The A5000 port is in restricted beta testing; a release is likely fairly soon. For more up to date information watch the newsgroup comp.sys.acorn.misc, or look on the WWW at http://whirligig.ecs.soton.ac.uk/~rmk92/armlinux.html; if you want to volunteer you should contact Martin Ebourne mje@soton.ac.uk.

David Miller is working on a port to the Sparc. It is at a very early stage; people who are willing to dedicate lots of time and have access to Sparc boxes for testing should get in touch with davem@caip.rutgers.edu.

None of the above ports will be capable of running Linux/386 binaries.

Linux port to the Aleph One 486 card (not the second processor card for the Risc PC yet, but the original PC-on-a-podule card) has been completed and appears stable. Full details on this version, and updates on general ports in progress, can be found on the WWW at http://www.ph.kcl.ac.uk/~amb/linux.html.

Question 1.5. How much hard disk space does Linux need ?

You can squeeze a more complete installation including X Windows into 80Mb. Installating almost all of Debian 0.93R6 takes around 500Mb, including some space for user files and spool areas.

Question 1.6. Is Linux PD ? Copyrighted ?

Full details are in the file COPYING in the Linux kernel sources (probably in /usr/src/linux on your system).

The licences of the utilities and programs which come with the installations vary; much of the code is from the GNU Project at the Free Software Foundation, and is also under the GPL.

Note that discussion about the merits or otherwise of the GPL should be posted to gnu.misc.discuss and not to the comp.os.linux groups.