Lots of updates on the install process, detailing how to
install PicoBSD on hard disks and CDROM images, and on the bootstrap sequence and the places where you can customise a PicoBSD image. Now if some of the -doc guys want to put this stuff in a nice handbook page, that would be extremely useful!
This commit is contained in:
Luigi Rizzo
parent
1c1676edca
commit
27530a537c
@ -229,7 +229,29 @@ manpage for the syntax.
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.It Pa config
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shell variables, sourced by the
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.Pa picobsd
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script (optional). Again, look at the standard
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script (optional). The most important variables here are
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.Pa MY_DEVS
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which should be set to the list of device which should be
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created in the
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.Pa /dev
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directory of the image (it is really the argument passed to
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.Pa MAKEDEV ,
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so you can refer to that manpage for the names), and the
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.Pa fd_size
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which can override the default size (in kilobytes) of the image.
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By default,
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.Pa fd_size=1440
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which produces an image suitable for a standard floppy.
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.Pp
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If you plan to store the image on a CDROM (e.g. using
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the El Torito floppy emulation), you can set
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.Pa fd_size=2880 .
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Same if you are planning to dump the image onto a hard disk
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(either in a partition or on the whole disk), in which case you
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are not even restricted to use one of the standard floppy sizes.
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Using a large image size per se does not waste RAM at runtime,
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because only the files that are actually loaded from the image
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contribute to the memory usage.
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.Pp
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.It Pa floppy.tree.exclude
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files from the standard floppy tree which are not needed (optional).
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@ -288,17 +310,100 @@ you first need to update them e.g. by running first
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.Pp
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as you would normally do for any change of this kind.
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.Pp
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.Sh INSTALLING PicoBSD
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.Pp
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.Ss Floppy install
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Historically,
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.Nm
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is run from a floppy disk, where it can be installed with a simple
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.Bd -literal -offset indent
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dd if=picobsd.bin of=/dev/rfd0
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.Ed
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.Pp
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and the floppy is ready to run.
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.Pp
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.Ss Hard disk install
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The same process can be used to store the image on a hard disk
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(entire volume or one of the slices):
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.Bd -literal -offset indent
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dd if=picobsd.bin of=/dev/ad2
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dd if=picobsd.bin of=/dev/ad2s3
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dd if=picobsd.bin of=/dev/ad2 oseek=NN
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.Ed
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.Pp
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The first form will install the image on the entire disk, and it
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should work in the same way as from a floppy.
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.Pp
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The second form will install the
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on slice number 3 (which should be large enough to store the
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content of the image). However the process will only have success if the
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partition does not contain a valid disklabel, otherwise the kernel will
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likely prevent overwriting the label. In this case you can use the
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third form, replacing NN with the actual start of the partition
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(as you can tell from
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.Nm fdisk
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).
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Note that after saving the image to the slice, it will not be
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recognised yet, you have to use the disklabel command to
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properly initialize the label (don't ask why!).
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One way to do this is
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.Bd -literal -offset indent
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disklabel -w ad0s2 auto
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disklabel -e ad0s2
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.Ed
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.Pp
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and from the editor enter a line corresponding to the actual partition, e.g.
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if the image has 2.88MB (5760 sectors) you need to enter the following
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line for the partition:
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.Bd -literal -offset indent
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a: 5760 0 4.2BSD 512 4096
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.Ed
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.Pp
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At this point the partition is bootable.
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Note that the image size can be smaller than the slice size
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(indicated as partition c:).
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.Pp
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.Ss CDROM install
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Another option is to put the image on a CDROM. Assuming your image
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for disk type
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.Pa foo
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is in the directory
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.Pa build_dir-foo
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then you can produce a bootable El Torito image (and burn it) with the
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following command:
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.Bd -literal -offset indent
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mkisofs -b picobsd.bin -c boot.catalog -d -N -D -R -T \\
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-o cd.img build_dir-foo
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burncd -f /dev/acd0c -s 4 data cd.img fixate
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.Ed
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.Pp
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Note that the image size is restricted to 1.44MB or 2.88MB, other sizes
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most likely will not work.
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.Pp
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.Ss Booting from the network
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Yet another way to use
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.Nm
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is to boot the image off the network.
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For this purpose you should use the uncompressed kernel which is
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available as a byproduct of the compilation. Refer to the documentation
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for network booting for more details, the
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.Nm
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kernel is bootable as a standard
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.Fx
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kernel.
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.Pp
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.Sh BOOTING PicoBSD
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To boot
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.Nm ,
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insert the floppy and reset the machine. The boot procedure is similar to the
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standard
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.Fx
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boot, but proceeds at a snail's pace. From the end of the POST
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(BIOS Power On Self Test) until the system is up and running takes
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anywhere between 1 and 3 minutes.
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boot.
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Booting from a floppy is normally rather slow (in the order of 1-2
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minutes), things are much faster if you store your image on
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a hard disk, Compact Flash, or CDROM.
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.Pp
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To speed up booting, you can use
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You can also use
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.Xr etherboot
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to load the preloaded, uncompressed kernel image
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which is a byproduct of the
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@ -307,21 +412,170 @@ build.
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In this case
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the load time is a matter of a few seconds, even on a 10Mbit/s
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ethernet.
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.Ss Swap space
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.Pp
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After booting,
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.Nm
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runs entirely from the memory file system. The floppies are no longer used, and
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even if there are hard disk drivers in the
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.Nm
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kernel, it does not access the drives. In particular, there is no swap space,
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so if you run out of memory, unpredictable things can happen.
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loads the root filesystem from memory file system, starts
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.Pa /sbin/init ,
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and passes control to a first startup script,
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.Pa /etc/rc .
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The latter populates the
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.Pa /etc
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and
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.Pa /root
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directories with the default files, then tries to identify the boot
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device (floppy, hard disk partition) and possibly override the content
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of the root filesystem with files read from the boot device.
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This allows you to store local configuration on the same media.
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After this phase the boot device is no longer used, unless the
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user specifically does it.
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.Pp
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After this, control is transferred to a second script,
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.Pa /etc/rc1 ,
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(can be overridden from the boot device).
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This one tries to associate a hostname to the system by using
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the MAC address of the first ethernet interface as a key, and
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.Pa /etc/hosts
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as a lookup table.
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Then control is passed to the main user configuration script,
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.Pa /etc/rc.conf ,
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which is supposed to override the value of a number of configuration
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variables which have been pre-set in
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.Pa /etc/rc.conf.defaults .
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You can use the
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.Pa $hostname
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variable to create different configurations from the same file.
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.Pa
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After taking control back,
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.Pa /etc/rc1 completes the initializations, and as part of this
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it configures network interfaces and optionally calls the
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firewall configuration script,
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.Pa /etc/rc.firewall ,
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where the user can store his own firewall configuration.
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.Pp
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Note that by default
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.Nm
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runs entirely off main memory, and has no swap space, unless you
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explicitly request it.
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The boot device is also not used anymore after
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.Pa /etc/rc1
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takes control, again unless you explicitly request it.
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.Pp
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.Pp
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.Sh CONFIGURING a PicoBSD system
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The operation of a
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.Nm
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system can be configured through a few files which are read at boot
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time, very much like a standard
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.Fx
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system. There are, however, some minor differences to reduce the
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number of files to store and/or customize, thus saving space.
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Among the files to configure we have the following:
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.Pp
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.Bl -tag -width "xxxxx" -compact
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.It Pa /etc/hosts
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Traditionally, this file contains the IP-to-hostname mappings.
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In addition to this, the PicoBSD version of this file also contains
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a mapping between Ethernet (MAC) addresses and hostnames, as follows:
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.Pp
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.Bd -literal -offset indent
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#ethertable start of the ethernet->hostname mapping
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# mac_address hostname
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# 00:12:34:56:78:9a pinco
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# 12:34:56:* pallino
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# * this-matches-all
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.Ed
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.Pp
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where the line containing "#ethertable" marks the start of the table.
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.Pp
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If the MAC address is not found, the script will prompt you to
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enter a hostname and IP address for the system, and these
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informations will be stored in the
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.Pa /etc/hosts
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file (in memory) so you can simply store them on disk later.
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.Pp
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Note that you can use wildcards in the address part, so a line
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like the last one in the example will match any MAC address and
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avoid the request.
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.Et
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.Pp
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.It Pa /etc/rc.conf
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This file contains a number of variables which control the
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operation of the system, such as interface configuration,
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router setup, network service startup, etc. .
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For the exact list and meaning of these variables see
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.Pa /etc/rc.conf.defaults .
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.Pp
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It is worth mentioning that some of the variables let you
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overwrite the content of some files in
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.Pa /etc .
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This option is available at the moment for
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.Pa /etc/host.conf
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and
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.Pa /etc/resolv.conf
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whose content is generally very short and suitable for this
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type of updating.
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In case you use these variables, remember to use newlines
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as appropriate, e.g.
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.Pp
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.Bd -literal -offset indent
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host_conf="# this goes into /etc/host.conf
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hosts
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bind"
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.Ed
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.Pp
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Although not mandatory in this file you should only set the
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variables indicated in
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.Pa /etc/rc.conf.defaults ,
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and avoid starting services which depend on having the network running.
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This can be done at a later time: if you set
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.Pa firewall_enable="YES" ,
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the
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.Pa /etc/rc.firewall
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script will be run after configuring the network interfaces,
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so you can set up your firewall and safely start network services or enable
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things such as routing and bridging.
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.Et
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.Pp
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.It Pa /etc/rc.firewall
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This script can be used to configure the
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.Nm ipfw
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firewall.
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On entry, the
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.Pa $fwcmd
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variable is set to the pathname of the firewall command,
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.Pa $firewall_type
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contains the value set in
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.Pa /etc/rc.conf ,
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and
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.Pa $hostname
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contains the name assigned to the host.
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.El
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.Pp
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There is a small script called
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.Nm update
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which can be used to edit and/or save to disk a copy of the files
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that you have modified after booting.
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The script takes one or more absolute pathnames, runs the
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editor on the files passed as arguments, and then saves a
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compressed copy of the files on the disk (mounting and
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unmounting the latter around the operation).
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.Pp
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If invoked without arguments,
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.Nm update
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edits and saves
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.Pa rc.conf
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.Pa rc.firewall
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and
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.Pa master.passwd .
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.Pp
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If one of the arguments is
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.Pa /etc
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(the directory name alone),
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then the command saves to disk (without editing)
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all the files in the directory for which a copy
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already exists on disk (e.g. as a result of a previous update).
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.Pp
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If you have a disk driver and a disk with a swap partition on it, and the swap
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partition does not contain a dump you want to keep, you can use this swap with
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.Nm .
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Use the
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.Xr swapon 8
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command.
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.Sh SEE ALSO
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.Xr crunchgen 1 ,
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.Xr swapon 8 ,
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