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.\" Copyright (c) 1999 Jakub Jelinek <jakub@redhat.com>
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.\" Portions of this manual page from lilo.conf documentation
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.\" Copyright (c) 1992-1998 Werner Almesberger
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.\" This program is distributed according to the Gnu General Public License.
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.\" See the file COPYING in the SILO source distribution.
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.TH SILO.CONF 5 "20 September 1999" "SILO"
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silo.conf \- File format used by SILO.
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The \fBsilo.conf\fP file is a configuration file for \fBSILO\fP
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which is read during booting.
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\fBsilo.conf\fP provides instructions for \fBSILO\fP. This includes
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which kernels or other operating systems to load and what options pass to
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them. Unlike \fBLILO\fP bootloader on the Intel platform, \fBSILO\fP reads
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and parses the configuration file at boot time. This means any
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changes can be made to the configuration file and if the system is shut down
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properly or the config file makes it to the disk, \fBSILO\fP will use it on
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\fBSILO\fP is able to boot kernels even without this configuration file or
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if this file is crippled or contains syntax errors, but the user has to
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enter full PROM names and full path of the images to load and all options
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required for them manually.
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The file consists of comments and variable assignments.
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Start with a \fI#\fP character, and continue to
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Consist of a single keyword and are followed by whitespace
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or the end of the file.
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Consist of the variable name, optional architecture scope,
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optional whitespace, a \fI=\fP character, optional whitespace, the value
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and required whitespace, or the end of the file.
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Allowed only for variable names \fIimage\fP and \fIother\fP. Must directly
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follow variable name without any whitespace. Consists of the \fI[\fP character,
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a subset of case-insensitive tokens \fIsun4\fP, \fIsun4c\fP, \fIsun4d\fP,
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\fIsun4e\fP, \fIsun4m\fP, \fIsun4u\fP, separated by \fI,\fP characters
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(no whitespace allowed in between) and ends with the \fI]\fP character.
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Some string variables are expecting file names. A file name format in \fBSILO\fP
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[<devicename>][<part>]<absolute_pathname>
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[<devicename>][<part>][\fB[\fP<m>\fB-\fP<n>\fB]\fP]
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The first form refers to a file or directory on some supported filesystem
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(currently \fIext2\fP, \fIext3\fP, \fIufs\fP, \fIromfs\fP or \fIiso9660\fP),
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the latter refers to a range of 512B blocks on a device. For a device block
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range, either <devicename>, or <part>, or [<m>-<n>] must be given. If the last
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part is not given, it defaults to [1-16] (ie. 7680 bytes from offset 512 in
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the device - normal SPARC bootblock location).
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Optional <devicename> is the PROM name of the device the file or range
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is located on. See below for its syntax. For v2 and P1275 PROMs the device
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name must be immediately followed by the \fI;\fP character. The default is
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the boot device SILO was booted from.
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Optional <part> is the 1 based partition number on the device. First
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partition is 1 (e.g. on \fI/dev/sda\fP in Linux is this \fI/dev/sda1\fP).
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The default is the default partition (the value of the \fIpartition\fP
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variable in the config file).
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<absolute_pathname> must start with a \fI/\fP character and is the
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pathname from the root of the filesystem on that device (unless it is the
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root filesystem this is different to the pathname you will see in Linux).
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<m> is the first block number (in blocksize 512 bytes) of the range to
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be loaded and <n> is the last block number plus one.
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SILO will transparently uncompress files when loading them if they are
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gzipped, unless the file is an initial ramdisk.
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Depend on the PROM version of the machine used during bootup. For older
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PROMs (v0), the device name syntax is:
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<xx>\fB(\fP<m>\fB,\fP<n>\fB,\fP<o>\fB)\fP
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<xx> is one of \fIsd\fP, \fIst\fP, \fIxd\fP, \fIxy\fP, \fIfd\fP, \fIle\fP, \fIie\fP,
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<m> is controller number as decimal number,
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<n> is device id as decimal number,
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and <o> is zero based partition number.
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For newer PROMs (v2) and all PROMs in the 64bit SPARC machines the syntax
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<fully_qualified_prom_device_name>[\fB:\fP<part_letter>]
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where the fully qualified PROM device name starts with a \fI/\fP character
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for the root of the PROM device tree and contains all the nodes from the
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root in the tree up to the disk device node. If some node contains more than
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one child node with the same name and the path has to go through such node,
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a \fI@\fP character followed by hexadecimal address pair is desirable to
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resolve the ambiguity. Optional partition number is a \fI:\fP character
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followed by a letter \fIa\fP (for first partition) through \fIh\fP (for
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last, 8th, partition). v2 PROM device names might look like:
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/sbus@3,0/SUNW,fas@3,8800000/sd@0,0
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/iommu/sbus/espdma@5,8400000/esp@5,8800000/sd@6,0:d
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/pci@1f,0/pci@1,1/ide@3/disk@2,0
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/pci@1f,4000/ide/ata@0,0/cmdk@0,0
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v2 PROM device names if specified as part of the file name (see above)
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should be followed by the \fI;\fP character to separate the device name from
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the optional Linux partition number (note that there can be two partition
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numbers specified, the latter takes precedence) and from the required
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Variable names are case insensitive, values of string variables are case
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Blanks and equal signs may only be part of a variable name or a value if
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they are escaped by a backslash or if the value is embedded in double
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quotes. An equal sign may not be the only character in a name or value.
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An escaped tab is converted to an escaped blank. An escaped newline is
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removed from the input stream. An escaped backslash (i.e. two
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backslashes) is converted to a backslash. Inside quoted strings, only
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double quotes, backslashes and newlines can be escaped.
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image=/boot/vmlinux.old
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\fB/etc/silo.conf\fP begins with a possibly empty global options section.
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This section contains all variable assignments up to the first \fIimage\fP
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or \fIother\fP setting.
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The following global options are recognized:
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Uses the specified image as the default boot image. If `default' is omitted,
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the image appearing first in the configuration file is used.
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.BI "message=" message_filename
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Specifies a file containing a message that is displayed before the boot
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.BI "password=" password
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Protect booting by a password. The password is given in cleartext in the
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configuration file. Because of that the configuration file should be only
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readable by the super user and the password should differ if possible from
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other passwords on the system.
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A password is only required to boot the image specified in
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\fB/etc/silo.conf\fP if parameters are specified on the command line
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or if the image is not specified in the configuration file at all (ie.
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arbitrary file load).
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Sets a timeout (in tenths of a second) for keyboard input. If no key is
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pressed for the specified time, the first image is automatically booted.
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This flag causes the same functionality as the \fI-t\fP command line
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option for the silo program. It's useful for not having to manually add
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that option everytime.
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.BI "secondary=" filename
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Forces the second stage boot loader to be other than /boot/second.b. Same
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as the \fI-b\fP command line option. This can be overriden by the command
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In addition to these global options, per-image options
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\fIappend\fP, \fIdevice\fP, \fIfill-reboot-cmd\fP, \fIimage\fP,
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\fIinitrd-prompt\fP, \fIinitrd-size\fP, \fIinitrd\fP,
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\fIother\fP, \fIpartition\fP, \fIpause-after\fP, \fIpause-message\fP,
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\fIramdisk\fP, \fIread-only\fP, \fIread-write\fP and \fIroot\fP can be
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specified in the global section. They are used as defaults if they aren't
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specified in the configuration sections of the respective kernel images
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and will be used also for the arbitrary images specified on the input line
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and not mentioned in the configuration file (unless overridden by input line
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.SH "PER-IMAGE SECTIONS"
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A per-image section starts with either a line
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\fBimage=\fP\fIfilename\fP
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(for booting from files) or
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\fBother=\fP\fIpartition_name\fP
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(for booting from device ranges).
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The \fIimage\fP or \fIother\fP tokens can be directly followed by
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architecture scope (see above). In that case, the image declaration will be
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only available if the architecture of the booting machine is listed in the
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scope. If it is not listed, the whole \fIimage\fP or \fIother\fP line and
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the following related section will be treated as not present in the config
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image[sun4c,sun4d,sun4m]=/boot/vmlinux32.gz
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will declare image with the specified filename only on sun4c, sun4d or
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SILO will transparently decompress gzipped images.
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\fIpartition_name\fP in the \fBother\fP setting is a normal filename whose
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syntax is described above, but without the pathname part. So it is either a
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single partition number (starting with 1), or a device name (for v2 and
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P1275 PROMs followed by \fI;\fP character) followed by such partition
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bootblock=/boot/old.b
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# Example with device for v0 PROM:
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# Example with device for v2 or P1275 PROM:
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other=/iommu/sbus/espdma/esp/sd@3,0;3
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The \fIfilename\fP above can also include two special tokens: \fIcat\fP and
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\fIls\fP. Both have to be followed by whitespace and some filename (directory
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name in the \fIls\fP case). \fIls\fP can have options between the \fIls\fP
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token and the directory name. \fIcat\fP causes the filename to be loaded and
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printed to the screen instead of being executed, \fIls\fP causes a directory
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listing to be generated to the screen. \fIls\fP uses syntax:
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\fBls\fP [\fB-\fP[\fBl\fP][\fBt\fP][\fBr\fP]] <dirname>
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Option \fBl\fP generates long listing instead of listing only filenames,
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option \fBt\fP sorts by mtime instead of name and \fBr\fP reverses the
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sorting. As both \fIcat\fP and \fIls\fP require white space between the
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token and the filename, you should probably surround it into double quotes
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image="cat /etc/passwd"
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image="ls /lib/modules/"
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From the \fIimage\fP or \fIother\fP line on until next \fIimage\fP or
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\fIother\fP line are variable assignments and flags for this image's
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section. The following options and flags are recognized:
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The boot loader uses the main file name (without its path) of each image
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specification to identify that image. A different name can be used by
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setting the variable `label'.
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A second name for the same entry can be used by specifying an alias.
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.BI "partition=" part_no
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Specifies the default partition number (a digit between 1 and 8, sda1 is
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part_no 1) to be used if some filename does not specify a partition number
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.BI "device=" device_name
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Specifies the default device name to be used if some filename does not
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specify a partition number explicitely. This defaults to the device
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\fBSILO\fP has been booted from if you don't specify \fIdevice\fP in either
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the global section or per-image section of the config file.
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Appends the options specified to the parameter line
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passed to the kernel. This is typically used to
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specify parameters of hardware that can't be
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entirely auto-detected or for which probing may be
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append = "video=sbusfb:off"
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.BI "literal=" string
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Like `append', but removes all other options (e.g. setting of the root
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device). Because vital options can be removed unintentionally with
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`literal', this option cannot be set in the global options section.
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This specifies the size of the optional RAM disk. A value of zero indicates
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that no RAM disk should be created. If this variable is omitted, the RAM
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disk size configured into the boot image is used.
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This specifies that the root file system should be mounted read-only.
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Typically, the system startup procedure re-mounts the root file system
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read-write later (e.g. after fsck'ing it).
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This specifies that the root file system should be mounted read-write.
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.BI "root=" root-device
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This specifies the device that should be mounted as root.
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.BI "proll=" filename
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This should be only used for JavaStation flash installs. It specifies a file
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that will be loaded at boot time and executed in order to emulate old Sun v2
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PROM on top of IEEE P1275 PROM called PROLL.
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.BI "initrd=" filename
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Specifies the file that will be loaded at boot time as the initial RAM disk.
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initrd=/images/initrd.img
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SILO will not decompress the initial ramdisk, the Linux kernel will do that.
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If the initial ramdisk does not fit on one media (usually floppy), you can
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split it into several pieces and separate the filenames in the list by
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\fI|\fP characters. In this case, you have to provide a non-zero
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\fIinitrd-size\fP and, if the images reside on different medias,
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\fIinitrd-prompt\fP as well.
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Example (on the first floppy is initrd1.img, on the second initrd2.img
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always in the root directory and the sum of both image sizes is 1700000
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initrd=/initrd1.img|/initrd2.img
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.BI "initrd-size=" size
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When more than one initial ramdisk part is specified in the \fIinitrd\fP
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setting, this option is required to be the sum of sizes of all the images
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mentioned on that line, in bytes. It is required so that SILO can reserve
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space for the image, eventhough size of some parts has not been determined
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If more than one initial ramdisk part is specified, wait for user pressing a
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key between loading the different images, so that the user can exchange
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media. This flag is needed if some initrd parts reside on the same device,
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but different removable media. On the other side, if you e.g. load one part
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from a floppy and the second part from a hard disk, such option is not
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needed (the question is who'd write something like that into silo.conf).
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.BI "bootblock=" filename
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For the \fIother\fP image section, if booting from some partition is desired
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but the bootblock on that partition has been saved off to some file and the
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bootblock in that partition contains something else (e.g. SILO bootblock),
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this option specifies the name of the file where the bootblock has been
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saved to. SILO loads the image from that file, pretends as if it had
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loaded it from the specified partition and executes it. This is e.g. useful
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if you have Solaris installed on the first partition of the disk and want to
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install SILO into the master boot record (ie. bootblock of the first
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partition). Then you should first save the Solaris bootblock into some file,
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\fBdd if=/dev/sda of=/boot/old.b bs=512 count=15 skip=1\fP
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then install SILO and put this snippet into \fIsilo.conf\fP:
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bootblock=/boot/old.b
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Note that this does not work correctly on UltraSPARC boxes at the moment.
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.BI "fill-reboot-cmd"
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This flag should be used only with Linux kernels. If specified for an image,
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it causes the file \fI/proc/sys/kernel/reboot-cmd\fP to be initialized by
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the device SILO has been booted from, image name of the kernel beeing loaded
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and all arguments to it specified either in the configuration file, or on
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the input line. This means that if the user does not modify that file and
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reboots the system, it should load the same kernel as last time and pass it
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If this flag is specified, SILO will stop after loading the kernel (and
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initial ramdisks if specified) and ask the user to press a key before
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.BI "pause-message=" string
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If \fIpause-after\fP is specified, this variable specifies the string to
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print to the user when asking him to press a key. The default is:
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Press ENTER to continue.
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Enables booting the image by hitting a single key when the cursor is at the
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first character in the input line, without the need to press <ENTER>
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afterwards. \fIsingle-key\fP requires that either the image's label or its
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alias (or both) is a single character. If you need to specify parameters for
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such an image, or if you want to boot some other image which happens to
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start with the same letter, then you need to start the input line with at
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least one space which will be removed before processing but will disable
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this single-key feature.
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This flag tells SILO that the image to be loaded is a Solaris kernel. This
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has been implemented so that users don't have to save the old Solaris
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bootblock or in case it has been lost. SILO then tries to use the Solaris
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ufsboot second stage loader to load specified kernel image. The usual kernel
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name is \fI/kernel/unix\fP (SILO automatically prepends the
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\fI/platform/<platform>\fP path before it if needed). SILO recognizes the
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special pathname \fI/kernel/unix\fP (with any device and/or partition) though
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and assumes the \fIsolaris\fP flag for it by default. Note that this method
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of loading Solaris might not work for you, as it is quite error prone due to
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different versions of Solaris and different PROMs.
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The recommended solution for sharing Solaris and Linux on the same disk is
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to install SILO into the Linux's own partition bootblock (as opposed to the
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master bootblock) and add PROM aliases to boot from the devices. E.g. if
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Solaris is installed on Linux device sda1 and Linux on sda4, \fIsilo.conf\fP
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could look like this:
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one would invoke SILO as:
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and in PROM (this depends on the PROM version, lets assume P1275)
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\fBsetenv boot-device /sbus/espdma/esp/sd@0,0:d\fP
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(so that by default it boots from the 4th (ie. Linux) partition) or:
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\fBnvalias linux /sbus/espdma/esp/sd@0,0:d\fP
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\fBnvalias solaris /sbus/espdma/esp/sd@0,0:a\fP
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so that one could already in PROM boot either with \fBboot linux\fP or with
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\fBboot solaris\fP. For the former, there would still be possibility to type
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\fBsolaris\fP on the SILO prompt to boot Solaris.
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\fBSILO\fP has been written by Jakub Jelinek <jakub@redhat.com> and
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the SparcLinux team (see documentation on the list of contributors).
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The latest version of the sources may be obtained by ftp/http from
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http://www.sparc-boot.org/
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man/silo.conf.5
