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diff --git a/share/doc/handbook/booting.sgml b/share/doc/handbook/booting.sgml new file mode 100644 index 0000000..a4371d6 --- /dev/null +++ b/share/doc/handbook/booting.sgml @@ -0,0 +1,165 @@ +<!-- This is a SGML version of the text on FreeBSD boot procedures + made by Poul-Henning Kamp <phk@FreeBSD.ORG> + + This conversion has been made by Ollivier Robert. + + $Id: boot-overview.sgml,v 1.1 1995/04/27 08:50:46 roberto Exp $ +--> +<!DOCTYPE linuxdoc PUBLIC "-//Linux//DTD linuxdoc//EN"> + + <article> + + <title>Boot overview</title> + <author>Poul-Henning Kamp, <tt/<phk@login.dknet.dk>/</author> + <date>v1.1, April 26th</date> + <abstract> + Booting FreeBSD is essentially a three step: Load the kernel, + determine the root filesystem and initialize user-land things. This + leads to some interesting possibilities as shown below... + </abstract> + + <toc> + + <sect>Loading a kernel + <p> + We presently have three basic mechanisms for loading the kernel: + <enum> + <item>biosboot + <item>dosboot + <item>netboot + </enum> + Each will be described in detail below. They all pass some + information to the kernel to help the kernel decide what to do + next. + + <sect1>Biosboot + <p> + Biosboot is our ``bootblocks'', it consists of two files, which + will be installed in the first 8Kbytes of the floppy or hard-disk + slice to be booted from. + + Biosboot can load a kernel from a FreeBSD filesystem. + + <sect1>Dosboot + <p> + Dosboot was written by DI. Christian Gusenbauer, and is + unfortunately at this time one of the few pieces of code that + isn't compilable under FreeBSD itself because it is written for + MicroSoft compilers. + + Dosboot will boot the kernel from a MS-DOS file or from a FreeBSD + filesystem partition on the disk. It attempts to negotiate with + the various and strange kinds of memory manglers that lurk in + high memory on MS/DOS systems and usually wins them for it's + case. + + <sect1>Netboot + <p> + Netboot will try to find a supported ethernet card, and use + BOOTP, TFTP and NFS to find a kernel file to boot. + + <sect>Determine the root filesystem + <p> + Once the kernel is loaded and the boot-code jumps to it, the kernel + will initialize itself, trying to determine what hardware is + present and so on, and then it needs to find a root filesystem. + + Presently we support the following types of rootfilesystems: + <itemize> + <item>UFS + <item>MSDOS + <item>MFS + <item>CD9660 + <item>NFS + </itemize> + + <sect1>UFS + <p> + This is the most normal type of root filesystem. It can reside on + a floppy or on harddisk. + + <sect1>MSDOS + <p> + While this is technically possible, it isn't particular useful, + because of ``FAT'' filesystems inability to make links, device + nodes and such ``UNIXisms''. + + <sect1>MFS + <p> + This is actually a UFS filesystem which has been compiled into + the kernel. That means that the kernel does not really need any + disks/floppies or other HW to function. + + <sect1>CD9660 + <p> + This is for using a CD-ROM as root filesystem. + + <sect1>NFS + <p> + This is for using a fileserver as root filesystem, basically + making it a diskless machine. + + <sect>Initialize user-land things + <p> + To get the user-land going, when the kernel has finished + initialization, it will create a with ``<tt/pid == 1/'' and execute + a program on the rootfilesystem, this program is normally + ``<tt>/sbin/init</tt>''. + + You can substitute any program for /sbin/init, as long as you keep + in mind that: + + there is no stdin/out/err unless you open it yourself, if you exit, + the machine panics signal handling is special for ``<tt/pid == + 1/''. + + + <sect>Interesting combinations + <p> + Boot a kernel with a MFS in it with a special <tt>/sbin/init</tt> + which... + <descrip> + <tag/A -- Using DOS/ + <itemize> + <item>mounts your <tt/C:/ as <tt>/C:</tt> + <item>Attaches <tt>C:/freebsd.fs</tt> on <tt>/dev/vn0</tt> + <item>mounts <tt>/dev/vn0</tt> as <tt>/rootfs</tt> + <item>makes symlinks<newline> + <tt>/rootfs/bin -> /bin</tt><newline> + <tt>/rootfs/etc -> /etc</tt><newline> + <tt>/rootfs/sbin -> /sbin</tt><newline> + ...<newline> + </itemize> + + Now you run FreeBSD without repartitioning your hard disk... + + <tag/B -- Using NFS/ + + NFS mounts your <tt>server:˜you/FreeBSD</tt> as + <tt>/nfs</tt>, chroots to <tt>/nfs</tt> and executes + <tt>/sbin/init</tt> there + + Now you run FreeBSD diskless, even though you don't control + the NFS server... + + <tag/C -- Start an X-server/ + + Now you have an Xterminal, which is better than that dingy + X-under-windows-so-slow-you-can-see-what-it-does thing that + your boss insist is better than forking our money on HW. + + <tag/D -- Using a tape/ + Takes a copy of <tt>/dev/rwd0</tt> and writes it to a remote tape + station or fileserver. + + Now you finally got that backup you should have made a year + ago... + + <tag>E -- Acts as a firewall/web-server/what do I know...</tag> + + This is particular interesting since you can boot from a write- + protected floppy, but still write to your root filesystem... + </descrip> + </article> + + |
