Опубликован: 06.08.2012 | Доступ: свободный | Студентов: 1189 / 25 | Оценка: 5.00 / 5.00 | Длительность: 53:41:00
Лекция 5:

Installing FreeBSD

Installing on an Alpha system

Installing FreeBSD on an Alpha (officially Compaq AXP) has a few minor differences due to the hardware itself. In principle, you perform the same steps to install FreeBSD on the Alpha architecture that you perform for the Intel architecture. See page 42 for some differences.

The easiest type of installation is from CD-ROM. If you have a supported CD-ROM drive and a FreeBSD installation CD for Alpha, you can start the installation by building a set of FreeBSD boot floppies from the files fbppies/kern.fp andfbppies/mfsroot.ftp as described for the Intel architecture on page 85. Use the CD-ROM marked "Alpha installation." From the SRM console prompt, insert the kern.flp floppy and type the following command to start the installation:

>>>boot dvaO

Insert the mfsroot.flp floppy when prompted and you will end up at the first screen of the install program. You can then continue as for the Intel architecture on page 59.

To install over the Net, fetch the floppy images from the ftp site, boot as above, then proceed as for the Intel architecture.

Once the install procedure has finished, you will be able to start FreeBSD/Alpha by typing something like this to the SRM prompt:

>>>boot dkcO

This instructs the firmware to boot the specified disk. To find the SRM names of disks in your machine, use the show device command:

>>>show device
dka0.       DKA0   TOSHIBA CD-ROM XM-57  3476
dkc0.0.0.1009.0    DKC0               RZ1BB-BS  0658
dkc100.1.0.1009.0  DKC100     SEAGATE ST34501W  0015
dva0.       DVA0
ewa0.       EWA0      00-00-F8-75-6D-01
pkc0.7.0.1009.0    PKC0          SCSI Bus ID 7  5.27
pqa0.       PQA0               PCI EIDE

This example comes from a Digital Personal Workstation 433au and shows three disks attached to the machine. The first is a CD-ROM called dka0 and the other two are disks and are called dkc0 and dkc100 respectively.

You can specify which kernel file to load and what boot options to use with the -file and -flags options to boot:

>>>boot -file kernel.old -flags s

To makeFreeBSD/Alpha boot automatically,use these commands:

>>>set boot_osflags a
>>>set bootdef_dev dkcO
>>>set auto_action BOOT

Upgrading an old version of FreeBSD

Paradoxically, upgrading an old version of FreeBSD is more complicated than installing from scratch. The reason is that you almost certainly want to keep your old configuration. There's enough material in this topic to fill a chapter, so that's what I've done: see "Keeping up to date" , for more details on how to upgrade a system.

How to uninstall FreeBSD

What, you want to remove FreeBSD? Why would you want to do that?

Seriously, if you decide you want to completely remove FreeBSD from the system, this is no longer a FreeBSD issue, it's an issue of whatever system you use to replace it. For example, on page 63 we saw how to remove a Microsoft partition and replace it with FreeBSD; no Microsoft software was needed to remove it. In the same way, you don't need any help from FreeBSD if you want to replace it with a different operating system.

If things go wrong

In this section, we'll look at the most common installation problems. Many of these are things that once used to happen and haven't been seen for some time: sysinstall has improved considerably, and modern hardware is much more reliable and easy to configure. You can find additional information on this topic in the section Known Hardware Problems in the file INSTALL.TXT on the first CD-ROM.

Problems with sysinstall

sysinstall is intended to be easy to use, but it is not very tolerant of errors. You may well find that you enter something by mistake and can’t get back to where you want to be. In case of doubt, if you haven't yet committed to the install, you can always just reboot.

Problems with CD-ROM installation

If you select to install from CD-ROM, you may get the message:

No CD-ROM device found

This might even happen if you have booted from CD-ROM! The most common reasons for this problem are:

  • You booted from floppy and forgot to put the CD-ROM in the drive before you booted. Sorry, this is a current limitation of the boot process. Restart the installation (press Ctrl-Alt-DEL or the reset button, or power cycle the computer).
  • You are using an ATAPI CD-ROM drive that doesn't quite fit the specification. In this case you need help from the FreeBSD developers. Send a message to FreeBSD-questions@FreeBSD.org and describe your CD-ROM as accurately as you can.
Can't boot

One of the most terrifying things after installing FreeBSD is if you find that the machine just won't boot. This is particularly bad if you have important data on the disk (either another operating system, or data from a previous installation of FreeBSD).

At this point, seasoned hackers tend to shrug their shoulders and point out that you still have the backup you made before you did do the installation. If you tell them you didn't do a backup, they tend to shrug again and move on to something else.

Still, all is probably not lost. The most frequent causes of boot failure are an incorrect boot installation or geometry problems. In addition, it's possible that the system might hang and never complete the boot process. All of these problems are much less common than they used to be, and a lot of the information about how to address them is a few years old, as they haven't been seen since.

Incorrect boot installation

It's possible to forget to install the bootstrap, or even to wipe it the existing bootstrap. That sounds like a big problem, but in fact it's easy enough to recover from. Refer to the description of the boot process on page 529, and boot from floppy disk or CD-ROM. Interrupt the boot process with the space bar. You might see:

BTX loader 1.00   BTX version is 1.01
BIOS drive A: is diskO
BIOS drive C: is diskl
BIOS drive D: is disk1
BIOS 639kB/130048kB available memory

FreeBSD/i386 bootstrap loader, Revision 0.8
(grog@freebie.example.com, Thu Jun 13 13:06:03 CST 2002)
Loading /boot/defaults/loader.conf

Hit [Enter] to boot immediately, or any other key for command prompt.
Booting [kernel] in 6 seconds...    press space bar here
ok unload                           unload the current kernel
ok set currdev=disk1s1a             and set the location of the newone
ok load /boot/kernel/kernel         load the kernel
ok boot                             then start it

This boots from the drive /dev/ad0s1a, assuming that you are using IDE drives. The correspondence between the name /dev/ad0s1a and disklsla goes via the information at the top of the example: BTX only knows the BIOS names, so you'd normally be looking for the first partition on drive C. After booting, install the correct bootstrap with bsdlabel -B or boot0cfg, and you should be able to boot from hard disk again.

Geometry problems

Things might continue a bit further: you elect to install booteasy, and when you boot, you get the Boot Manager prompt, but it just prints F? at the boot menu and won't accept any input. In this case, you may have set the hard disk geometry incorrectly in the partition editor when you installed FreeBSD. Go back into the partition editor and specify the correct geometry for your hard disk. You may need to reinstall FreeBSD from the beginning if this happens.

It used to be relatively common that sysinstall couldn't calculate the correct geometry for a disk, and that as a result you could install a system, but it wouldn't boot. Since those days, sysinstall has become a lot smarter, but it's still barely possible that you'll run into this problem.

If you can’t figure out the correct geometry for your machine, and even if you don't want to run Microsoft on your machine, try installing a small Microsoft partition at the beginning of the disk and install FreeBSD after that. The install program sees the Microsoft partition and tries to infer the correct geometry from it, which usually works. After the partition editor has accepted the geometry, you can remove the Microsoft partition again. If you are sharing your machine with Microsoft, make sure that the Microsoft partition is before the FreeBSD partition.

Alternatively, if you don't want to share your disk with any other operating system, select the option to use the entire disk (a in the partition editor). You're less likely to have problems with this option.

System hangs during boot

A number of problems may lead to the system hanging during the boot process. All the known problems have been eliminated, but there's always the chance that something new will crop up. In general, the problems are related to hardware probes, and the most important indication is the point at which the boot failed. It's worth repeating the boot with the verbose fag: again, refer to the description of the boot process on page 529. Interrupt the boot process with the space bar and enter:

Hit [Enter] to boot immediately,  or any other key for command prompt.
Booting [kernel] in 6 seconds...     press space bar here
ok set boot_verbose                  set a verbose boot
ok boot                              then continue

This fag gives you additional information that might help diagnose the problem. See "Starting and stopping the system" for more details of what the output means.

If you're using ISA cards, you may need to reconfigure the card to match the kernel, or change the file /boot/device.hints to match the card settings. See the example on page 609. Older versions of FreeBSD used to have a program called UserConfig to perform this function, but it is no longer supported.