557 lines
20 KiB
Plaintext
557 lines
20 KiB
Plaintext
The Linux+FreeBSD mini-HOWTO
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Niels Kristian Bech Jensen nkbj@image.dk
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v1.11, 30 March 2000
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This document describes how to use Linux and FreeBSD on the same sys
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tem. It introduces FreeBSD and discusses how the two operating systems
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can cooperate, e.g. by sharing swap space. You should probably have
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some experience with Linux or FreeBSD and hard drive partitioning
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(fdisk) before you read this document. The tips herein are tested
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using FreeBSD 2.2.2, but they should be valid for newer versions as
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well. Do not hesitate to mail me if you have comments, questions or
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suggestions about this document. I would also like to hear from people
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who have experience using Linux together with NetBSD or OpenBSD.
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______________________________________________________________________
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Table of Contents
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1. What is FreeBSD?
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2. The FreeBSD way of labelling hard drives
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2.1 FreeBSD ``slices'' and ``partitions''
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2.2 Drive and partition labelling in Linux and FreeBSD
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3. Sharing swap space between Linux and FreeBSD
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3.1 Installing and preparing Linux
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3.2 Installing FreeBSD
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3.3 Setting up the FreeBSD swap partition in Linux
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4. Booting FreeBSD using LILO
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5. Mounting filesystems
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5.1 Mounting UFS filesystems under Linux
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5.2 Mounting ext2fs filesystems under FreeBSD
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6. Running foreign binaries
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6.1 Running FreeBSD binaries under Linux
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6.2 Running Linux binaries under FreeBSD
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7. Information resources
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8. Credits and legal stuff
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8.1 Legal stuff
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______________________________________________________________________
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1. What is FreeBSD?
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FreeBSD <http://www.freebsd.org/> is a free Unix-like operating system
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much like Linux. The main difference is that, while the Linux kernel
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has been written from scratch, FreeBSD is based on the freely
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redistributable parts of 4.4BSD (Berkeley Software Distribution) known
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as 4.4BSD-lite. This fact might lead some people to suggest that
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FreeBSD is closer to being ``real'' UNIX® than Linux. FreeBSD runs
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only on the Intel PC platform (i386 and higher); ports to the DEC
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Alpha and Sun Sparc platforms are being worked on at the moment.
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NetBSD <http://www.netbsd.org/> and OpenBSD <http://www.openbsd.org/>
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are similar to FreeBSD, and both run on several platforms. Hardware
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requirements for all these *BSD systems are similar to those for
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Linux.
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The development of FreeBSD is managed in a different way than the
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Linux development. A core team of developers serve as arbitrators and
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provide leadership for the project. Big changes are discussed in
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advance on the mailing lists. The FreeBSD project has two development
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trees (just like Linux): ``-CURRENT'' and ``-STABLE''. The
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``-CURRENT'' development tree is where the development of new features
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happens. Development to the ``-STABLE'' tree are restricted to bug
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fixes and some thoroughly tested new features.
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FreeBSD can be used and (re-)distributed freely just as Linux. Most
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parts of the system are released under the BSD copyright; the rest is
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under the GNU GPL or other open-source <http://www.opensource.org/>
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licences.
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2. The FreeBSD way of labelling hard drives
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Linux and FreeBSD label hard drives and partitions after two
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differents schemes. This section explains the main differences between
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the two schemes. In fact the FreeBSD labelling scheme is an adaption
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of the traditional BSD labelling style ported to live within the PC's
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fdisk partitions. Thus it is very similar to other BSD-based Unix
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systems such as NetBSD, OpenBSD, Ultrix, Digital Unix, SunOS, and
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Solaris.
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2.1. FreeBSD ``slices'' and ``partitions''
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FreeBSD needs one of the four entries in the partition table on your
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PC's hard drive. This primary partition is called a ``slice'' in
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FreeBSD terminology. It then uses the disklabel program to make up to
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eight partitions in this primary partition. These logical partitions
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are called ``partitions'' in FreeBSD terminology. This concept is
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similar to the way Linux (and DOS) handles logical partitions in an
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extended partition. You cannot install FreeBSD in an extended
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partition made by Linux (or DOS). Note that the Linux fdisk program
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doesn't display the BSD partitions in a FreeBSD slice from the main
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menu, but it can display BSD disklabel information if you give the
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command `b'. The output is something like this (/dev/hda4 is the
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FreeBSD slice):
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bash# fdisk /dev/hda
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Command (m for help): p
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Disk /dev/hda: 64 heads, 63 sectors, 621 cylinders
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Units = cylinders of 4032 * 512 bytes
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Device Boot Begin Start End Blocks Id System
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/dev/hda1 * 1 1 27 54400+ 83 Linux native
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/dev/hda2 28 28 55 56448 83 Linux native
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/dev/hda3 56 56 403 701568 83 Linux native
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/dev/hda4 404 404 621 439488 a5 BSD/386
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Command (m for help): b
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Reading disklabel of /dev/hda4 at sector 1624897.
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BSD disklabel command (m for help): p
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8 partitions:
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# size offset fstype [fsize bsize cpg]
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a: 64512 1624896 4.2BSD 0 0 0 # (Cyl. 404 - 419)
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b: 104832 1689408 swap # (Cyl. 420 - 445)
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c: 878976 1624896 unused 0 0 # (Cyl. 404 - 621)
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e: 64512 1794240 4.2BSD 0 0 0 # (Cyl. 446 - 461)
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f: 645120 1858752 4.2BSD 0 0 0 # (Cyl. 462 - 621)
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BSD disklabel command (m for help): q
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bash#
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The letters `a'...`f' in the first column are the same labels as shown
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below in the example for a FreeBSD slice. There are three special
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partitions in BSD parlace. The letter `a' designates the root
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partition, `b' designates the swap partition, while `c' designates the
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whole slice. See the FreeBSD documentation for more information on the
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``standard'' way of assigning these letters to different partition
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types.
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2.2. Drive and partition labelling in Linux and FreeBSD
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The hard drives are labelled in the following way in Linux and
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FreeBSD:
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Linux FreeBSD
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First IDE drive /dev/hda /dev/wd0
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Second IDE drive /dev/hdb /dev/wd1
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First SCSI drive /dev/sda /dev/sd0
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Second SCSI drive /dev/sdb /dev/sd1
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The partitions (FreeBSD slices) on an IDE drive are labelled in the
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following way (/dev/hda is used as an example):
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Linux FreeBSD
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First primary partition /dev/hda1 /dev/wd0s1
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Second primary partition /dev/hda2 /dev/wd0s2
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Third primary partition /dev/hda3 /dev/wd0s3
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Fourth primary partition /dev/hda4 /dev/wd0s4
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The partitions in my FreeBSD slice is labelled in the following way.
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It is the labelling you get by default. It is possible to change the
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labelling if you do a custom installation of FreeBSD (/dev/hda4 is the
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FreeBSD slice in the example):
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Linux label FreeBSD label FreeBSD mount point
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/dev/hda5 /dev/wd0s4a /
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/dev/hda6 /dev/wd0s4b swap
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/dev/hda7 /dev/wd0s4e /var
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/dev/hda8 /dev/wd0s4f /usr
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If you run dmesg in Linux you will see this as (The linux kernel must
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be build with UFS filesystem support for this to work. See section
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``Installing and preparing Linux''):
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Partition check:
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hda: hda1 hda2 hda3 hda4 < hda5 hda6 hda7 hda8 >
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If you have installed FreeBSD in the /dev/sd1s3 slice (/dev/sdb3 in
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Linux parlace), and /dev/sdb2 is a Linux extended partition containing
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two logical partitions (/dev/sdb5 and /dev/sdb6), the previous example
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would look like this:
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Linux label FreeBSD label FreeBSD mount point
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/dev/sdb7 /dev/sd1s3a /
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/dev/sdb8 /dev/sd1s3b swap
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/dev/sdb9 /dev/sd1s3e /var
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/dev/sdb10 /dev/sd1s3f /usr
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This will be shown as
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Partition check:
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sdb: sdb1 sdb2 < sdb5 sdb6 > sdb3 < sdb7 sdb8 sdb9 sdb10 >
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in the output from dmesg.
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If you have a Linux extended partition after your FreeBSD slice you're
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in for trouble, because most Linux kernels installation floppies are
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build without UFS support, they will not recognise the FreeBSD
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partitions inside the slice. What should have have been seen as
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(/dev/hda3 is the FreeBSD slice and /dev/hda4 is the Linux extended
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partition)
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Partition check:
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hda: hda1 hda2 hda3 < hda5 hda6 hda7 hda8 > hda4 < hda9 hda10 >
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is seen as:
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Partition check:
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hda: hda1 hda2 hda3 hda4 < hda5 hda6 >
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This can give you the wrong device assignment and cause the loss of
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data. My advice is to always put your FreeBSD slice after any Linux
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extended partitions, and do not change any logical partitions in your
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Linux extended partitions after installing FreeBSD!
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3. Sharing swap space between Linux and FreeBSD
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This section describes how I got Linux and FreeBSD to share a swap
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partition. There may be other ways to get the same result. You can
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install FreeBSD before Linux if you want to, just pay attention to the
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order of the partitions in the FreeBSD slice.
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3.1. Installing and preparing Linux
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The first step is to install Linux as normal. You have to leave space
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for the FreeBSD slice at your hard drive. You don't have to make a
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Linux swap partition, but if you want one, put it in the space you
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want to allocate for FreeBSD. That way you can delete the Linux swap
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partition later and use the space for FreeBSD.
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When you have installed Linux you have to build a new kernel. Read The
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Linux Kernel HOWTO if this is new to you. You have to include both UFS
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filesystem support (read only) and BSD disklabel (FreeBSD partition
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tables) support:
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UFS filesystem support (read only) (CONFIG_UFS_FS) [N/y/m/?] y
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BSD disklabel (FreeBSD partition tables) support (CONFIG_BSD_DISKLABEL) [N/y/?]
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(NEW) y
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Install the new kernel and reboot. Remove any line including the word
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swap from your /etc/fstab file if you have made a Linux swap
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partition. Make sure you have a working Linux boot floppy with the
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new kernel. Now you are ready to install FreeBSD.
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3.2. Installing FreeBSD
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Install FreeBSD as described in the FreeBSD documentation. Remove the
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Linux swap partition if you have made one (you can use the FreeBSD
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fdisk program.) Pay attention to the order of the partitions in the
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FreeBSD slice. If you use the default labelling the second partition
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will be the swap partition. Complete the installation of FreeBSD and
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reboot into Linux using the new Linux boot floppy.
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3.3. Setting up the FreeBSD swap partition in Linux
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Run dmesg when you have booted into Linux. In the output you should
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see something like this:
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Partition check:
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hda: hda1 hda2 hda3 hda4 < hda5 hda6 hda7 hda8 >
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This means that /dev/hda4 is your FreeBSD slice, while /dev/hda5,
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/dev/hda6, /dev/hda7 and /dev/hda8 are the FreeBSD partitions. If your
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swap partition is the second partition in the slice, it will be
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/dev/hda6.
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You have to put the following line into your Linux /etc/fstab file to
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enable the swap partition:
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/dev/hda6 none swap sw 0 0
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While FreeBSD can use any type of partition as swap space, Linux needs
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a special signature in the swap partition. This signature is made by
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mkswap. FreeBSD ruins this signature when it uses the shared swap
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partition, so you will have to run mkswap each time you boot into
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Linux. To do this automagically you have to find the script that runs
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swapon at boot time. In Red Hat Linux it is /etc/rc.d/rc.sysinit. Put
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the following line into that file just before swapon -a:
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awk -- '/swap/ && ($1 !~ /#/) { system("mkswap "$1"") }' /etc/fstab
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This will run mkswap on any swap partitions in /etc/fstab every time
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you boot except if they are commented out (having ``#'' as the first
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character in the line.)
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Run free to check out the size of the swap space when you have
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rebooted into Linux. You should also reboot into FreeBSD to make sure
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everything works as expected. If it does not, you have probably used
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the wrong partition as swap partition. The only solution to that
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problem is to reinstall FreeBSD and try again. Experience is a great
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teacher. :-)
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4. Booting FreeBSD using LILO
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You can easily boot FreeBSD with LILO. Do not install the FreeBSD boot
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selector (Booteasy) if you want to use LILO. Append the following
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lines to your /etc/lilo.conf file and run lilo (assuming the FreeBSD
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slice is /dev/hda4):
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other=/dev/hda4
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table=/dev/hda
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label=FreeBSD
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If you have installed FreeBSD on the second SCSI drive, use something
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like this (the FreeBSD slice being /dev/sdb2):
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other=/dev/sdb2
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table=/dev/sdb
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loader=/boot/chain.b
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label=FreeBSD
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5. Mounting filesystems
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5.1. Mounting UFS filesystems under Linux
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Unfortunately the UFS driver in the Linux 2.0.xx kernels do not
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include support for FreeBSD. When you try to mount a FreeBSD
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filesystem, you just get some error messages (the filesystem actually
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gets mounted, but you cannot do anything with it.) This problem has
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been solved in the newer Linux kernels (version 2.1.87 and higher.)
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There is another version of the UFS driver for Linux 2.0.xx kernels
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(xx <= 30) on metalab.unc.edu (the former sunsite.unc.edu)
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<ftp://metalab.unc.edu/pub/Linux/ALPHA/ufs/>. It is called U2FS and
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the current version is u2fs-0.4.3.tar.gz. A version of U2FS
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(ufs-0.4.4.tar.gz) for Linux 2.0.31 and higher (2.0.xx; not 2.1.xx)
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can be found at this site <http://www.mathi.uni-
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heidelberg.de/~flight/projects/u2fs/> along with further information
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about U2FS (and UFS.)
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Now you have to build a new kernel with support for the U2FS
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filesystem and BSD disklabels. See section ``Installing and preparing
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Linux'' for more information on this. You can leave out UFS filesystem
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support from the kernel when you use U2FS.
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When you have installed the new kernel, you can mount your UFS
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filesystems (all the partitions in the FreeBSD slice except the swap
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partition) with a command like this:
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mount -t u2fs /dev/hda8 /mnt
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You should use a command like
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mount -t ufs /dev/hda8 /mnt
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if you use a Linux kernel version 2.1.87 or higher. From Linux kernel
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version 2.1.112 you must add -o ufstype=44bsd to the command like
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this:
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mount -t ufs -o ufstype=44bsd /dev/hda8 /mnt
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The UFS (and U2FS) driver is read-only. That is; you can read from the
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UFS filesystems but you cannot write to them. An experimental read-
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write UFS driver has replaced the read-only driver in Linux kernels
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version 2.1.112 and higher; writing to FreeBSD partitions is supported
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from version 2.1.127.
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5.2. Mounting ext2fs filesystems under FreeBSD
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To mount ext2fs filesystems under FreeBSD, you first have to build a
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new kernel with ext2fs support. Read the FreeBSD handbook
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<http://www.freebsd.org/handbook/> to learn how to do that. Put the
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line
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options "EXT2FS"
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in your kernel configuration file for the new kernel.
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When you have booted with the new kernel, you can mount an ext2fs
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filesystem by giving a command like:
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mount -t ext2fs /dev/wd0s3 /mnt
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Due to a bug in FreeBSD 2.2.8 and earlier you will have to unmount all
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ext2fs filesystems before you shut down FreeBSD if you are using these
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any of these versions. If you shut down FreeBSD with an ext2fs
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filesystem mounted, FreeBSD cannot sync the UFS filesystems. This
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results in fsck being run the next time FreeBSD is booted. You can
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work around this bug by putting the line:
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umount -a -t ext2fs
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in the /etc/rc.shutdown file. The bug has been fixed in FreeBSD 3.x.
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6. Running foreign binaries
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6.1. Running FreeBSD binaries under Linux
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The iBCS package has support for running FreeBSD binaries under Linux;
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but it's old and unmaintained. I cannot get it to work. Please let me
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know if you have had better luck with this.
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6.2. Running Linux binaries under FreeBSD
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FreeBSD has the ability to run Linux binaries, both in a.out and ELF
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formats. To do this you have to take the following three steps:
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1. You have to enable Linux compatibility. To do this (in FreeBSD
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2.2.2 --- details may vary in other versions) you have to edit your
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/etc/rc.conf file and change
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linux_enable="NO"
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to
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linux_enable="YES"
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and reboot. Another way to load the Linux binary support is to execute
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the command /usr/bin/linux. This way you don't have to reboot, and you
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don't always have the Linux binary support loaded (i.e. you save mem
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ory.) Remember to add the line
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options COMPAT_LINUX
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to the FreeBSD kernel config file if you build a new FreeBSD kernel.
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2. You have to install the Linux shared libraries if your Linux
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binaries are dynamically linked. The libraries are included in
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FreeBSD 2.2.{2,5,6} as the package linux_lib-2.4.tgz (newer
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versions might be available.) Run the following command to install
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the package:
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pkg_add <path_to_package>/linux_lib-2.4.tgz
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<path_to_package> is the directory where the package is stored. You
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may also load it off the net by:
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pkg_add ftp://ftp.freebsd.org/pub/FreeBSD/packages-stable/All/linux_lib-2.4.tgz
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or by re-running /stand/sysinstall. Enter ``Configure'', ``Packages''
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and use the menus. You should execute the following command if you are
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running statically linked Linux binaries:
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brandelf -t Linux <name_of_statically_linked_linux_binary>
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3. Install the Linux program(s) you want to run. The program(s) can be
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installed on either UFS or ext2fs filesystems. See section
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``Mounting ext2fs filesystems under FreeBSD'' for more information
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about using ext2fs filesystems under FreeBSD.
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I have successfully run the Linux versions of Applixware 4.3 and
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Netscape 3.01 (both ELF format) under FreeBSD 2.2.2 using this method
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(yes, I know there is a native FreeBSD version of Netscape 4.) The
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Linux versions of acroread and StarOffice 3 and 4 also work well under
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FreeBSD. StarOffice 5 depends on native Linux threads and currently do
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not work under FreeBSD. Read the FreeBSD documentation for more
|
||
information on this topic.
|
||
|
||
|
||
7. Information resources
|
||
|
||
The latest version of this mini-HOWTO can be downloaded from this site
|
||
<http://www.image.dk/~nkbj/> in several formats (including SGML and
|
||
PostScript.) The document has been translated into Japanese by Mr.
|
||
Teruyoshi Fujiwara as part of the JF project
|
||
<ftp://jf.linux.or.jp/pub/JF/other-formats/>.
|
||
|
||
You can find some articles about the difference between Linux and
|
||
FreeBSD here
|
||
<http://www.futuresouth.com/~fullermd/freebsd/bsdvlin.html>.
|
||
|
||
You can find more informations about FreeBSD (and download the whole
|
||
system) at this site <http://www.freebsd.org/>. You can also buy the
|
||
system on CDROMs from Walnut Creek CDROM <http://www.cdrom.com> (their
|
||
servers are running FreeBSD.)
|
||
|
||
The Linux Kernel HOWTO (and this mini-HOWTO) is released as part of
|
||
The Linux Documentation Project <http://www.linuxdoc.org/>.
|
||
|
||
|
||
8. Credits and legal stuff
|
||
|
||
Thanks to the members of the *BSD user group in Denmark
|
||
<http://www.bsd-dk.dk/> for answering the questions of a FreeBSD
|
||
newbie, to Mr. Takeshi Okazaki for bringing the existence of U2FS to
|
||
my attention, and to Mr. David O'Brien for valuable suggestions.
|
||
|
||
|
||
8.1. Legal stuff
|
||
|
||
Trademarks are owned by their owners.
|
||
|
||
Although the information given in this document is believed to be
|
||
correct, the author will accept no liability for the content of this
|
||
document. Use the tips and examples given herein at your own risk.
|
||
|
||
Copyright © 1997-2000 by Niels Kristian Bech Jensen. This document may
|
||
be distributed only subject to the terms and conditions set forth in
|
||
the LDP License at http://www.linuxdoc.org/COPYRIGHT.html
|
||
<http://www.linuxdoc.org/COPYRIGHT.html>.
|
||
|
||
|
||
|