Опубликован: 06.08.2012 | Доступ: свободный | Студентов: 1330 / 47 | Оценка: 5.00 / 5.00 | Длительность: 53:41:00
Лекция 2:

Before you install

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Аннотация: Using old hardware; PC Hardware; How the system detects hardware; Configuring ISA cards; PCMCIA, PC Card and Card Bus; Universal Serial Bus; Disks; Disk data layout; Making the file systems; Disk size limitations; Display hardware; The hardware; Compaq/Digital Alpha machines; The CD-ROM distribution.
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FreeBSD runs on just about any modern PC, Alpha or 64 bit SPARC machine. You can skip this chapter and the next and move to chapter 3, and you'll have a very good chance of success. Nevertheless, it makes things easier to know the contents of this chapter before you start. If you do run into trouble, it will give you the background information you need to solve the trouble quickly and simply.

FreeBSD also runs on most Intel-based laptops; in general the considerations above apply for laptops as well. In the course of the book we'll see examples of where laptops require special treatment.

Most of the information here applies primarily to Intel platforms. We'll look at the Compaq Alpha architecture on page 42. The first release of FreeBSD to support the SPARC 64 architecture is 5.0, and support is still a little patchy. At the time of going to press, it's not worth describing, since it will change rapidly. The instructions on the CD-ROM distribution are currently the best source of information on running FreeBSD on SPARC 64.

Using old hardware

FreeBSD runs on all relatively recent machines. In addition, a lot of older hardware that is available for a nominal sum, or even for free, runs FreeBSD quite happily, though you may need to take more care in the installation.

FreeBSD does not support all PC hardware: the PC has been on the market for over 20 years, and it has changed a lot in that time. In particular:

  • FreeBSD does not support 8 bit and 16 bit processors. These include the 8086 anв 8088, which were used in the IBM PC and PC-XT and clones, and the 80286, used in the IBM PC-AT and clones.
  • The FreeBSD kernel no longer supports ST-506 and ESDI drives. You're unlikely to have any of these: they're now so old that most of them have failed. The wd driver still includes support for them, but it hasn't been tested, and if you want to use this kind of drive you might find it better to use FreeBSD Release 3. See page 32 to find out how to identify these drives. You can get Release 3 of FreeBSD from ftp://ftp.FreeBSD.org/pub/FreeBSD/releases/i386/3.x-STABLE. You'll have toper-form a network installation.
  • Memory requirements for FreeBSD have increased significantly in the last few years, and you should consider 16 MB a minimum size, though nobody has recently checked whether it wouldn't install in, say,12MB. FreeBSD Release 3 still runs in 4 MB, though you need 5 MB for installation.

If you're planning to install FreeBSD on an old machine, consider the following to be an absolute minimum:

  • PC with 80386 CPU, Alpha-based machine with SRM firmware.
  • 16 MB memory (Intel) or 24 MB (Alpha).
  • 80 MB free disk space (Intel). Nobody has tried an installation on an Alpha or SPARC machine with less than 500 MB, though you can probably reduce this value significantly.

You don't absolutely need a keyboard and display board: many FreeBSD machines run server tasks with neither keyboard nor display. Even then, though, you may find it convenient to put a display board in the machine to help in case you run into trouble.

When I say absolute minimum, I mean it. You can't do very much with such a minimal system, but for some purposes it might be adequate. You can improve the performance of such a minimal system significantly by adding memory. Before you go to the trouble to even try such a minimal installation, consider the cost of another 16 MB of memory. And you can pick up better machines than this second-hand for $50. Is the hassle worth it?

To get full benefits from a desktop or laptop FreeBSD system (but not from a machine used primarily as a server), you should be running the X Window system. This uses more memory. Consider 32 MB a usable minimum here, though thanks to FreeBSD's virtual memory system, this is not such a hard limit as it is with some other systems.

The speed of a virtual memory-based system such as FreeBSD depends at least as much on memory performance as on processor performance. If you have, say, a 486DX-33 and 16 MB of memory, upgrading memory to 32 MB will probably buy you more performance than upgrading the motherboard to a Pentium 100 and keeping the 16 MB memory. This applies for a usual mix of programs, in particular, programs that don't perform number crunching.

Any SPARC 64 machine runs FreeBSD acceptably, as the machines are relatively new. If you're running Intel or Alpha, consider the following the minimum for getting useful work done with FreeBSD and X:

  • PC with 80486DX/2-66, or Alpha-based machine
  • 32 MB memory (i386) or 64 MB (Alpha)
  • SVGA display board with 2 MB memory, 1024x768
  • Mouse
  • 200 MB free disk space
Your mileage may vary. During the review phase of an earlier edition of this book, one of the reviewers stated that he was very happy with his machine, which has a 486-33 processor, 16MB main memory, and 1 MB memory on his display board. He said that it ran a lot faster than his Pentium 100 at work, which ran Microsoft. The moral: if your hardware doesn't measure up to the recommended specifi cation, don't be discouraged. Try it out anyway.

Beyond this minimum, FreeBSD supports a large number of other hardware components.

Device drivers

The FreeBSD kernel is the only part of the system that can access the hardware. It includes device drivers, which control the function of peripheral devices such as disks, displays and network boards. When you install new hardware, you need a driver for it.

There are two ways to get a driver into the kernel: you can build a kernel that includes the driver code, or you can load a driver module (Kernel Loadable Module or kld) into the kernel at run time. Not all drivers are available as klds. If you need one of these drivers, and it's not included in the standard kernel, you have to build a new kernel. We look at building kernels in Chapter 33.

The kernel configuration supplied with FreeBSD distributions is called GENERIC after the name of the configuration file that describes it. It contains support for most common devices, though support for some older hardware is missing, usually because it conflicts with more modern drivers. For a full list of currently supported hardware, read the web page http://www.FreeBSD.org/releases/ and select the link Hardware Notes for the release you're interested in. This file is also available on installed FreeBSD systems as /usr/share/doc/en_US.ISO_8859-1/books/faq/hardware.html. It is also available in other languages; see the subdirectories of /usr/share/doc.

PC Hardware

This section looks at the information you need to understand to install FreeBSD on the i386 architecture. In particular, in the next section we'll look at how FreeBSD detects hardware, and what to do if your hardware doesn't correspond to the system's expectations. On page 32 we'll see how FreeBSD and other PC operating systems handle disk space, and how to set up your disk for FreeBSD.

Some of this information also applies to the Alpha and SPARC 64 architectures. We'll look at the differences for the Alpha architecture on page 42. Currently the SPARC 64 implementation is changing too fast to describe it in a meaningful manner.

Since the original PC, a number of hardware standards have come, and some have gone:

  • The original PC had an 8 bit bus. Very few of these cards are still available, but they are compatible with the ISA bus (see the next item).
  • The PC AT, introduced in 1984, had a 16 bit 80286 processor. To support this processor, the bus was widened to 16 bits. This bus came to be known as the Industry Standard Architecture, or ISA.This standard is still not completely dead, and many new mother boards support it. Most older motherboards have a number of ISA slots.
  • The ISA bus has a number of severe limitations, notably poor performance. This became a problem very early. In 1985, IBM introduced the PS/2 system, which addressed this issue with a new bus, the so-called Micro Channel Architecture or MCA. Although successful for IBM, MCA was not adopted by other manufacturers, and FreeBSD does not support it at all. IBM no longer produces products based on MCA
  • In parallel to MCA, other manufacturers introduced a bus called the Extended Industry Standard Architecture, or EISA. As the name suggests, it is a higher-performance extension of ISA, and FreeBSD supports it. Like MCA, it is obsolete.
  • EISA still proved to be not fast enough for good graphics performance. In the late 80s, a number of local bus solutions appeared. They had better performance, but some were very unreliable. FreeBSD supported most of them, but you can't rely on it. It's best to steer clear of them.
  • Finally, in the early 1990s, Intel brought out a new bus called Peripheral Component Interconnect, or PCI. PCI is now the dominant bus on a number of architectures. Most modern PC add-on boards are PCI.
  • Compared to earlier buses, PCI is much faster. Most boards have a 32bit wide data bus, but there is also a 64 bit PCI standard. PCI boards also contain enough intelligence to enable the system to configure them, which greatly simplifies installation of the system or of new boards.
  • Modern motherboards also have an AGP (Accelerated Graphics Port) slot specifically designed to support exactly one graphic card. As the name implies, it's faster even than PCI, but its optimized for graphics only. FreeBSD supports it, of course otherwise it couldn't run on modern hardware.
  • Most laptops have provision for external plug-in cards that conform to the PC Card (formerly called PCMCIA) or CardBus standards. These cards are designed to be inserted into and removed from a running system. FreeBSD has support for these cards; we'll look at them in more detail on page 30.
  • More and more, the basic serial and parallel ports installed on early PCs are being replaced by a Universal Serial Bus or USB. We’ll look at it on page 31.
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