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.TH SILO 8 "11 February 2000" "Linux"
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\fBSILO\fP \- Sparc Improved boot LOader
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\fB/sbin/silo\fP [-r root_path] [-b secondary] [-i primary] [-C config-file]
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[-S backup-file] [-s backup-file] [-J flash-image ]
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\fBSILO\fP can be used to boot Linux, SunOS, and/or Solaris. It is a program
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that runs from the PROM on your SPARC machine and allows for loading of
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operating systems. It also has extended features like the ability to load
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Linux kernels arbitrarily from an \fIext2\fP, \fIext3\fP, \fIufs\fP,
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\fIromfs\fP or \fIiso9660\fP filesystem.
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The PROM in the SPARC at boot time loads a bootblock from a boot
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device. This bootblock is quite short, so a full featured boot loader does
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not fit into it, especially since filesystems like \fIext2\fP reserve only 1024
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bytes for it and the partition table itself takes 512 bytes.
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That's why SILO consists of a collection of first stage loaders which are
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just able to load a second stage loader which already understands all
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supported filesystems and handles the config file, input line editing and
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actual loading of operating systems.
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The program \fB/sbin/silo\fP is used to install the first stage loader by
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copying the right first stage loader into the bootblock (unless the correct
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first stage is already installed and the \fI-f\fP option is not used to
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force it), writes the block number of the first block of the second stage
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loader (usually \fB/boot/second.b\fP) into it and into the second stage
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loader it records all the block numbers of \fBsecond.b\fP and the name and
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location of the configuration file. The configuration file itself is parsed
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by the boot loader at boot time. See \fBsilo.conf(5)\fP for details.
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This means that the \fB/sbin/silo\fP program must be run only if you install
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a new version of \fISILO\fP or if you move the second stage loader on the
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disk. Unlike the \fILILO\fP bootloader on the Intel platform, you don't have
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to rerun it every time you make a change into \fB/etc/silo.conf\fP or when
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you install new kernels.
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\fB/sbin/silo\fP used to assist in creating SPARC bootable CDs, but this
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feature has been moved into the \fBmkisofs(8)\fP program and you only need
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to put \fBSILO\fP first and second stage loaders and the configuration on
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the CD before running it.
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.SH "COMMAND\-LINE OPTIONS"
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This does a chroot into \fIroot_path\fP before performing any actions.
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This tells SILO to use \fIsecondary\fP as the second stage loader instead
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of \fB/boot/second.b\fP
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Install \fIprimary\fP as the first stage loader instead of the default one
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(depending on other command line options and architecture of the machine
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\fB/sbin/silo\fP is being run on it is either \fB/boot/first.b\fP,
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\fB/boot/ultra.b\fP or \fB/boot/fd.b\fP).
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specify alternate config file instead of \fB/etc/silo.conf\fP. The config
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file must reside on the same physical disk (though it can be on
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different partitions) as the secondary loader (usually \fB/boot/second.b\fP).
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This forces saving your old bootblock into file \fIbackup-file\fP.
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This forces saving your old bootblock into file \fIbackup-file\fP
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if and only if \fIbackup-file\fP does not exist yet.
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force PROM version to be 0 or 2 (default is autodetection).
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force overwriting of bootblock.
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store bootblock into the same partition as second stage loader.
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By default SILO on SCSI/IDE disks writes bootblock into masterboot
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(bootblock of partition starting at cylinder 0), with
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you change this behaviour.
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Generate the bootblock for booting from the \fIromfs\fP filesystem.
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To create a bootable \fIromfs\fP filesystem, usually floppy, prepare the
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tree for that filesystem and run \fBgenromfs(8)\fP and make sure you pass it
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the \fB-a 512 -A 2048,/..\fP options. Then mount it and run \fB/sbin/silo\fP
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on it with the \fB-F\fP option. The procedure usually goes like this:
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\fBgenromfs -d \fP\fIdirectory\fP\fB/ -f \fP\fIdevice\fP\fB -a 512 -A 2048,/..\fP
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\fBmount -t romfs \fP\fIdevice mountpoint\fP
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\fBsilo -r \fP\fImountpoint\fP\fB -i /boot/fd.b -F\fP
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\fBumount \fP\fImountpoint\fP
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.BI "-J " flash-image
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Generate the bootblock for booting JavaStation off an flash image.
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To create it, prepare the tree for that filesystem and run \fBgenromfs(8)\fP
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and make sure you pass it the \fB-a512\fP option. You have to keep 1KB of
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space before the filesystem for the ELF bootblock. THe procedure usually
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\fBdd if=/dev/zero of=\fP\fIflash.img\fP\fB bs=1k count=1\fP
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\fBgenromfs -a 512 -f \fP\fIromfs.img\fP\fB -d \fP\fIflash/\fP
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\fBcat \fP\fIromfs.img\fP\fB >> \fP\fIflash.img\fP
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\fBrm -f \fP\fIromfs.img\fP
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\fBlosetup \fP\fI/dev/loop0\fP\fB -o 1024 \fP\fIflash.img\fP
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\fBmount -t romfs -o ro \fP\fI/dev/loop0\fP\fB \fP\fI/mnt\fP
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\fBsilo -J \fP\fIflash.img\fP\fB -i /boot/ieee32.b -r \fP\fI/mnt\fP
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\fBumount \fP\fI/mnt\fP
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\fBlosetup -d \fP\fI/dev/loop0\fP
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\fBjsflash \fP\fIflash.img\fP
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Assume the machine is an UltraSPARC (the default is obviously the machine
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\fB/sbin/silo\fP is running on). This can be useful e.g. if you plan to move
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a disk from a 32bit box to a 64bit box, you run \fB/sbin/silo -f -u\fP and
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then after the shutdown move the disk.
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Assume the machine is not an UltraSPARC.
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Print PROM version and exit.
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Usually, when silo is run, it reads and checks the syntax of the silo.conf
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that will be used when the system boots. This is generally good, but
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sometimes you may wish to create a boot block when no silo.conf is
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available yet. The \fB-a\fP option will allow this check to fail. USE WITH
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.SH "BOOT TIME OPERATION"
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When the PROM boots from a disk and partition on which SILO is installed, it
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will print the string \fBSILO\fP to the screen (if the second stage loader
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is moved away or is crippled it might actually print less letters from that
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string and die). If \fItimeout\fP is specified in \fBsilo.conf(5)\fP, it
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will wait like that until the user presses some key or until the timeout
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expires. If the timeout expires, the default image is booted, otherwise SILO
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continues normal operation, ie. prints the string \fBboot:\fP and waits for
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At the prompt, you can enter the \fIlabel\fP or
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\fIalias\fP of some image present in the config file, plus additional
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arguments you want to give it and \fBSILO\fP will boot such image, give it
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all the arguments specified in the config and all the arguments you gave on
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the command line. Entering an empty line will cause the default image to be
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boot: \fBlinux.old init=/bin/sh\fP
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The arguments you pass on the line after the name of the image to be loaded
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are basically kernel arguments which are normally specified in the
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\fIappend\fP variable in \fBsilo.conf(5)\fP. In addition to that, several
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special arguments are handled by \fBSILO\fP internally and are not passed to
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the kernel. These include \fIinitrd\fP, \fIinitrd-size=\fPnumber,
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\fIinitrd-prompt\fP, \fIpause-after\fP and \fIshow-arguments\fP.
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\fIshow-arguments\fP causes the arguments which will be passed to the kernel
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to be printed on the screen before the kernel is loaded, the other options
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ressemble flags and string variables of the same names from
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You can also enter one of the special keywords, \fBhalt\fP or \fBhelp\fP.
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\fBhalt\fP causes \fBSILO\fP to return PROM, \fBhelp\fP prints some short
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incomplete help message.
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If you want to load some image or other operating system not mentioned in
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the config file (or if the config file could not be loaded because it has
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not been found or had syntax errors in it - \fBSILO\fP will print a message
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about this in such a case), you can load arbitrary image from any local
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\fIext2\fP, \fIext3\fP, \fIufs\fP, \fIromfs\fP or \fIiso9660\fP filesystem
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and give it arbitrary arguments. \fBSILO\fP will handle transparent
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decompression of gzipped images. You type in the fully qualified \fBSILO\fP
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file name or partition name and arguments. For the syntax of the fully qualified
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\fBSILO\fP file names and partition names see \fBsilo.conf(5)\fP.
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boot: \fB/pci@1f,4000/ide/ata@0,0/cmdk@0,0;4/boot/vmlinux.new root=/dev/hda4\fP
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boot: \fB2/boot/vmlinux initrd=/boot/initrd.img\fP
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boot: \fBsd(0,2,0)2/boot/vmlinux.gz root=/dev/sdc2 init=/bin/sh ro\fP
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If there are \fIsingle-key\fP images in the config file, then they will be
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loaded as soon as you press that key at the beginning of the input line.
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If you want to give them arguments or load a different image which starts
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with that letter, you can type a space at the beginning of the input line so
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that the image is not autostarted.
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You can also view short files and see directory listings.
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Details are listed in \fBsilo.conf(5)\fP, here just a few examples:
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boot: \fBcat /etc/silo.conf\fP
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boot: \fBcat /sbus/espdma@1,280000/esp/sd@2,0;5/etc/inittab\fP
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boot: \fBls -lt /lib/modules/\fP
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boot: \fBls /pci@1f,4000/ide/ata@0,0/cmdk@0,0;2/lib/\fP
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\fBSILO\fP operation can be password protected in two different ways (in
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addition to no password protection at all). Either a password will be
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required to load any image, or password will be required to load any image
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not mentioned in \fBsilo.conf\fP or if the user gives some arguments to some
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image mentioned there.
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was written by Jakub Jelinek (jakub@redhat.com) and is released
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under the conditions of the GNU General Public License. See the file
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COPYING for details. This man page was written by Donald Barnes
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(djb@redhat.com) and updated by the author.
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\fBsilo.conf(5)\fP, \fBmkisofs(8)\fP, \fBgenromfs(8)\fP
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removed
man/silo.8
