System Administration Commands boot(1M)
NAME
boot - start the system kernel or a standalone program
SYNOPSIS
SPARC
boot [OBP names] [file] [-aLV] [-F object] [-D default-file]
[-Z dataset] [boot-flags] [--] [client-program-args]
x86
kernel$ /platform/i86pc/kernel/$ISADIR/unix [boot-args]
[-B prop=val [,val...]
DESCRIPTION
Bootstrapping is the process of loading and executing a
standalone program. For the purpose of this discussion,
bootstrapping means the process of loading and executing the
bootable operating system. Typically, the standalone program
is the operating system kernel (see kernel(1M)), but any
standalone program can be booted instead. On a SPARC-based
system, the diagnostic monitor for a machine is a good exam-
ple of a standalone program other than the operating system
that can be booted.
If the standalone is identified as a dynamically-linked exe-
cutable, boot will load the interpreter (linker/loader) as
indicated by the executable format and then transfer control
to the interpreter. If the standalone is statically-linked,
it will jump directly to the standalone.
Once the kernel is loaded, it starts the UNIX system, mounts
the necessary file systems (see vfstab(4)), and runs
/sbin/init to bring the system to the "initdefault" state
specified in /etc/inittab. See inittab(4).
SPARC Bootstrap Procedure
On SPARC based systems, the bootstrap procedure on most
machines consists of the following basic phases.
After the machine is turned on, the system firmware (in
PROM) executes power-on self-test (POST). The form and scope
of these tests depends on the version of the firmware in
your system.
After the tests have been completed successfully, the
firmware attempts to autoboot if the appropriate flag has
been set in the non-volatile storage area used by the
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System Administration Commands boot(1M)
firmware. The name of the file to load, and the device to
load it from can also be manipulated.
These flags and names can be set using the eeprom(1M) com-
mand from the shell, or by using PROM commands from the ok
prompt after the system has been halted.
The second level program is either a fileystem-specific boot
block (when booting from a disk), or inetboot or wanboot
(when booting across the network).
Network Booting
Network booting occurs in two steps: the client first
obtains an IP address and any other parameters necessary to
permit it to load the second-stage booter. The second-stage
booter in turn loads the boot archive from the boot device.
An IP address can be obtained in one of three ways: RARP,
DHCP, or manual configuration, depending on the functions
available in and configuration of the PROM. Machines of the
sun4u and sun4v kernel architectures have DHCP-capable
PROMs.
The boot command syntax for specifying the two methods of
network booting are:
boot net:rarp
boot net:dhcp
The command:
boot net
without a rarp or dhcp specifier, invokes the default method
for network booting over the network interface for which net
is an alias.
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The sequence of events for network booting using
RARP/bootparams is described in the following paragraphs.
The sequence for DHCP follows the RARP/bootparams descrip-
tion.
When booting over the network using RARP/bootparams, the
PROM begins by broadcasting a reverse ARP request until it
receives a reply. When a reply is received, the PROM then
broadcasts a TFTP request to fetch the first block of inet-
boot. Subsequent requests will be sent to the server that
initially answered the first block request. After loading,
inetboot will also use reverse ARP to fetch its IP address,
then broadcast bootparams RPC calls (see bootparams(4)) to
locate configuration information and its root file system.
inetboot then loads the boot archive by means of NFS and
transfers control to that archive.
When booting over the network using DHCP, the PROM broad-
casts the hardware address and kernel architecture and
requests an IP address, boot parameters, and network confi-
guration information. After a DHCP server responds and is
selected (from among potentially multiple servers), that
server sends to the client an IP address and all other
information needed to boot the client. After receipt of this
information, the client PROM examines the name of the file
to be loaded, and will behave in one of two ways, depending
on whether the file's name appears to be an HTP URL. If it
does not, the PROM downloads inetboot, loads that file into
memory, and executes it. inetboot loads the boot archive,
which takes over the machine and releases inetboot. Startup
scripts then initiate the DHCP agent (see dhcpagent(1M)),
which implements further DHCP activities.
If the file to be loaded is an HTP URL, the PROM will use
HTP to load the referenced file. If the client has been
configured with an HMAC SHA-1 key, it will check the
integrity of the loaded file before proceeding to execute
it. The file is expected to be the wanboot binary. The WAN
boot process can be configured to use either DHCP or NVRAM
properties to discover the install server and router and the
proxies needed to connect to it. When wanboot begins execut-
ing, it determines whether sufficient information is avail-
able to it to allow it to proceed. If any necessary informa-
tion is missing, it will either exit with an appropriate
error or bring up a command interpreter and prompt for
further configuration information. Once wanboot has obtained
the necessary information, it loads the boot loader into
memory by means of HTP. If an encryption key has been
installed on the client, wanboot will verify the boot
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loader's signature and its accompanying hash. Presence of an
encryption key but no hashing key is an error.
The wanboot boot loader can communicate with the client
using either HTP or secure HTP. If the former, and if the
client has been configured with an HMAC SHA-1 key, the boot
loader will perform an integrity check of the root file sys-
tem. Once the root file system has been loaded into memory
(and possibly had an integrity check performed), the boot
archive is transferred from the server. If provided with a
bootlogger URL by means of the wanboot.conf(4) file, wan-
boot will periodically log its progress.
Not all PROMs are capable of consuming URLs. You can deter-
mine whether a client is so capable using the list-
security-keys OBP command (see monitor(1M)).
WAN booting is not currently available on the x86 platform.
The wanboot Command Line
When the client program is wanboot, it accepts client-
program-args of the form:
boot ... -o opt1[,opt2[,...]
where each option may be an action:
dhcp
Require wanboot to obtain configuration parameters by
means of DHCP.
prompt
Cause wanboot to enter its command interpreter.
One of the interpreter commands listed below.
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...or an assignment, using the interpreter's parameter names
listed below.
The wanboot Command Interpreter
The wanboot command interpreter is invoked by supplying a
client-program-args of "-o prompt" when booting. Input con-
sists of single commands or assignments, or a comma-
separated list of commands or assignments. The configuration
parameters are:
host-ip
IP address of the client (in dotted-decimal notation)
router-ip
IP address of the default router (in dotted-decimal
notation)
subnet-mask
subnet mask (in dotted-decimal notation)
client-id
DHCP client identifier (a quoted ASCI string or hex
ASCI)
hostname
hostname to request in DHCP transactions (ASCI)
http-proxy
HTP proxy server specification (IPADR[:PORT])
The key names are:
3des
the triple DES encryption key (48 hex ASCI characters)
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aes
the AES encryption key (32 hex ASCI characters)
sha1
the HMAC SHA-1 signature key (40 hex ASCI characters)
Finally, the URL or the WAN boot CGI is referred to by means
of:
bootserver
URL of WAN boot's CGI (the equivalent of OBP's file
parameter)
The interpreter accepts the following commands:
help
Print a brief description of the available commands
var=val
Assign val to var, where var is one of the configuration
parameter names, the key names, or bootserver.
var=
Unset parameter var.
list
List all parameters and their values (key values
retrieved by means of OBP are never shown).
prompt
Prompt for values for unset parameters. The name of each
parameter and its current value (if any) is printed, and
the user can accept this value (press Return) or enter a
new value.
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go
Once the user is satisfied that all values have been
entered, leave the interpreter and continue booting.
exit
Quit the boot interpreter and return to OBP's ok prompt.
Any of these assignments or commands can be passed on the
command line as part of the -o options, subject to the OBP
limit of 128 bytes for boot arguments. For example, -o
list,go would simply list current (default) values of the
parameters and then continue booting.
iSCSI Boot
iSCSI boot is currently supported only on x86. The host
being booted must be equipped with NIC(s) capable of iBFT
(iSCSI Boot Firmware Table) or have the mainboard's BIOS be
iBFT-capable. iBFT, defined in the Advanced Configuration
and Power Interface (ACPI) 3.0b specification, specifies a
block of information that contains various parameters that
are useful to the iSCSI Boot process.
Firmware implementing iBFT presents an iSCSI disk in the
BIOS during startup as a bootable device by establishing the
connection to the iSCSI target. The rest of the process of
iSCSI booting is the same as booting from a local disk.
To configure the iBFT properly, users need to refer to the
documentation from their hardware vendors.
Booting from Disk
When booting from disk, the OpenBoot PROM firmware reads the
boot blocks from blocks 1 to 15 of the partition specified
as the boot device. This standalone booter usually contains
a file system-specific reader capable of reading the boot
archive.
If the pathname to the standalone is relative (does not
begin with a slash), the second level boot will look for the
standalone in a platform-dependent search path. This path is
guaranteed to contain /platform/platform-name. Many SPARC
platforms next search the platform-specific path entry
/platform/hardware-class-name. See filesystem(5). If the
pathname is absolute, boot will use the specified path. The
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boot program then loads the standalone at the appropriate
address, and then transfers control.
Once the boot archive has been transferred from the boot
device, Solaris can initialize and take over control of the
machine. This process is further described in the "Boot
Archive Phase," below, and is identical on all platforms.
If the filename is not given on the command line or other-
wise specified, for example, by the boot-file NVRAM vari-
able, boot chooses an appropriate default file to load based
on what software is installed on the system and the capabil-
ities of the hardware and firmware.
The path to the kernel must not contain any whitespace.
Booting from ZFS
Booting from ZFS differs from booting from UFS in that, with
ZFS, a device specifier identifies a storage pool, not a
single root file system. A storage pool can contain multiple
bootable datasets (that is, root file systems). Therefore,
when booting from ZFS, it is not sufficient to specify a
boot device. One must also identify a root file system
within the pool that was identified by the boot device. By
default, the dataset selected for booting is the one identi-
fied by the pool's bootfs property. This default selection
can be overridden by specifying an alternate bootable
dataset with the -Z option.
Boot Archive Phase
The boot archive contains a file system image that is
mounted using an in-memory disk. The image is self-
describing, specifically containing a file system reader in
the boot block. This file system reader mounts and opens the
RAM disk image, then reads and executes the kernel contained
within it. By default, this kernel is in:
/platform/`uname -i`/kernel/unix
If booting from ZFS, the pathnames of both the archive and
the kernel file are resolved in the root file system (that
is, dataset) selected for booting as described in the previ-
ous section.
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The initialization of the kernel continues by loading neces-
sary drivers and modules from the in-memory filesystem until
I/O can be turned on and the root filesystem mounted. Once
the root filesystem is mounted, the in-memory filesystem is
no longer needed and is discarded.
OpenBoot PROM boot Command Behavior
The OpenBoot boot command takes arguments of the following
form:
ok boot [device-specifier] [arguments]
The default boot command has no arguments:
ok boot
If no device-specifier is given on the boot command line,
OpenBoot typically uses the boot-device or diag-device NVRAM
variable. If no optional arguments are given on the command
line, OpenBoot typically uses the boot-file or diag-file
NVRAM variable as default boot arguments. (If the system is
in diagnostics mode, diag-device and diag-file are used
instead of boot-device and boot-file).
arguments may include more than one string. All argument
strings are passed to the secondary booter; they are not
interpreted by OpenBoot.
If any arguments are specified on the boot command line,
then neither the boot-file nor the diag-file NVRAM variable
is used. The contents of the NVRAM variables are not merged
with command line arguments. For example, the command:
ok boot -s
ignores the settings in both boot-file and diag-file; it
interprets the string "-s" as arguments. boot will not use
the contents of boot-file or diag-file.
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With older PROMs, the command:
ok boot net
took no arguments, using instead the settings in boot-file
or diag-file (if set) as the default file name and arguments
to pass to boot. In most cases, it is best to allow the boot
command to choose an appropriate default based upon the sys-
tem type, system hardware and firmware, and upon what is
installed on the root file system. Changing boot-file or
diag-file can generate unexpected results in certain cir-
cumstances.
This behavior is found on most OpenBoot 2.x and 3.x based
systems. Note that differences may occur on some platforms.
The command:
ok boot cdrom
...also normally takes no arguments. Accordingly, if boot-
file is set to the 64-bit kernel filename and you attempt to
boot the installation CD or DVD with boot cdrom, boot will
fail if the installation media contains only a 32-bit ker-
nel.
Because the contents of boot-file or diag-file can be
ignored depending on the form of the boot command used,
reliance upon boot-file should be discouraged for most pro-
duction systems.
When executing a WAN boot from a local (CD or DVD) copy of
wanboot, one must use:
ok boot cdrom -F wanboot - install
Modern PROMs have enhanced the network boot support package
to support the following syntax for arguments to be pro-
cessed by the package:
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[protocol,] [key=value,]*
All arguments are optional and can appear in any order. Com-
mas are required unless the argument is at the end of the
list. If specified, an argument takes precedence over any
default values, or, if booting using DHCP, over configura-
tion information provided by a DHCP server for those parame-
ters.
protocol, above, specifies the address discovery protocol to
be used.
Configuration parameters, listed below, are specified as
key=value attribute pairs.
tftp-server
IP address of the TFTP server
file
file to download using TFTP or URL for WAN boot
host-ip
IP address of the client (in dotted-decimal notation)
router-ip
IP address of the default router
subnet-mask
subnet mask (in dotted-decimal notation)
client-id
DHCP client identifier
hostname
hostname to use in DHCP transactions
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http-proxy
HTP proxy server specification (IPADR[:PORT])
tftp-retries
maximum number of TFTP retries
dhcp-retries
maximum number of DHCP retries
The list of arguments to be processed by the network boot
support package is specified in one of two ways:
o As arguments passed to the package's open method,
or
o arguments listed in the NVRAM variable network-
boot-arguments.
Arguments specified in network-boot-arguments will be pro-
cessed only if there are no arguments passed to the
package's open method.
Argument Values
protocol specifies the address discovery protocol to be
used. If present, the possible values are rarp or dhcp.
If other configuration parameters are specified in the new
syntax and style specified by this document, absence of the
protocol parameter implies manual configuration.
If no other configuration parameters are specified, or if
those arguments are specified in the positional parameter
syntax currently supported, the absence of the protocol
parameter causes the network boot support package to use the
platform-specific default address discovery protocol.
Manual configuration requires that the client be provided
its IP address, the name of the boot file, and the address
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of the server providing the boot file image. Depending on
the network configuration, it might be required that
subnet-mask and router-ip also be specified.
If the protocol argument is not specified, the network boot
support package uses the platform-specific default address
discovery protocol.
tftp-server is the IP address (in standard IPv4 dotted-
decimal notation) of the TFTP server that provides the file
to download if using TFTP.
When using DHCP, the value, if specified, overrides the
value of the TFTP server specified in the DHCP response.
The TFTP RQ is unicast to the server if one is specified as
an argument or in the DHCP response. Otherwise, the TFTP RQ
is broadcast.
file specifies the file to be loaded by TFTP from the TFTP
server, or the URL if using HTP. The use of HTP is trig-
gered if the file name is a URL, that is, the file name
starts with http: (case-insensitive).
When using RARP and TFTP, the default file name is the ASCI
hexadecimal representation of the IP address of the client,
as documented in a preceding section of this document.
When using DHCP, this argument, if specified, overrides the
name of the boot file specified in the DHCP response.
When using DHCP and TFTP, the default file name is con-
structed from the root node's name property, with commas (,)
replaced by periods (.).
When specified on the command line, the filename must not
contain slashes (/).
The format of URLs is described in RFC 2396. The HTP server
must be specified as an IP address (in standard IPv4
dotted-decimal notation). The optional port number is speci-
fied in decimal. If a port is not specified, port 80
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(decimal) is implied.
The URL presented must be "safe-encoded", that is, the pack-
age does not apply escape encodings to the URL presented.
URLs containing commas must be presented as a quoted string.
Quoting URLs is optional otherwise.
host-ip specifies the IP address (in standard IPv4 dotted-
decimal notation) of the client, the system being booted. If
using RARP as the address discovery protocol, specifying
this argument makes use of RARP unnecessary.
If DHCP is used, specifying the host-ip argument causes the
client to follow the steps required of a client with an
"Externally Configured Network Address", as specified in RFC
2131.
router-ip is the IP address (in standard IPv4 dotted-decimal
notation) of a router on a directly connected network. The
router will be used as the first hop for communications
spanning networks. If this argument is supplied, the router
specified here takes precedence over the preferred router
specified in the DHCP response.
subnet-mask (specified in standard IPv4 dotted-decimal nota-
tion) is the subnet mask on the client's network. If the
subnet mask is not provided (either by means of this argu-
ment or in the DHCP response), the default mask appropriate
to the network class (Class A, B, or C) of the address
assigned to the booting client will be assumed.
client-id specifies the unique identifier for the client.
The DHCP client identifier is derived from this value.
Client identifiers can be specified as:
o The ASCI hexadecimal representation of the iden-
tifier, or
o a quoted string
Thus, client-id="openboot" and client-id=6f70656e626f6f74
both represent a DHCP client identifier of 6F70656E626F6F74.
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Identifiers specified on the command line must must not
include slash (/) or spaces.
The maximum length of the DHCP client identifier is 32
bytes, or 64 characters representing 32 bytes if using the
ASCI hexadecimal form. If the latter form is used, the
number of characters in the identifier must be an even
number. Valid characters are 0-9, a-f, and A-F.
For correct identification of clients, the client identifier
must be unique among the client identifiers used on the sub-
net to which the client is attached. System administrators
are responsible for choosing identifiers that meet this
requirement.
Specifying a client identifier on a command line takes pre-
cedence over any other DHCP mechanism of specifying identif-
iers.
hostname (specified as a string) specifies the hostname to
be used in DHCP transactions. The name might or might not be
qualified with the local domain name. The maximum length of
the hostname is 255 characters.
Note -
The hostname parameter can be used in service environments
that require that the client provide the desired hostname
to the DHCP server. Clients provide the desired hostname
to the DHCP server, which can then register the hostname
and IP address assigned to the client with DNS.
http-proxy is specified in the following standard notation
for a host:
host [":"" port]
...where host is specified as an IP ddress (in standard IPv4
dotted-decimal notation) and the optional port is specified
in decimal. If a port is not specified, port 8080 (decimal)
is implied.
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tftp-retries is the maximum number of retries (specified in
decimal) attempted before the TFTP process is determined to
have failed. Defaults to using infinite retries.
dhcp-retries is the maximum number of retries (specified in
decimal) attempted before the DHCP process is determined to
have failed. Defaults to of using infinite retries.
x86 Bootstrap Procedure
On x86 based systems, the bootstrapping process consists of
two conceptually distinct phases, kernel loading and kernel
initialization. Kernel loading is implemented in GRUB (GRand
Unified Bootloader) using the BIOS ROM on the system board,
and BIOS extensions in ROMs on peripheral boards. The BIOS
loads GRUB, starting with the first physical sector from a
hard disk, DVD, or CD. If supported by the ROM on the net-
work adapter, the BIOS can also download the pxegrub binary
from a network boot server. Once GRUB is located, it exe-
cutes a command in a menu to load the unix kernel and a
pre-constructed boot archive containing kernel modules and
data.
If the device identified by GRUB as the boot device contains
a ZFS storage pool, the menu.lst file used to create the
GRUB menu will be found in the dataset at the root of the
pool's dataset hierarchy. This is the dataset with the same
name as the pool itself. There is always exactly one such
dataset in a pool, and so this dataset is well-suited for
pool-wide data such as the menu.lst file. After the system
is booted, this dataset is mounted at /poolname in the root
file system.
There can be multiple bootable datasets (that is, root file
systems) within a pool. By default, the file system in which
file name entries in a menu.lst file are resolved is the one
identified by the pool's bootfs property (see zpool(1M)).
However, a menu.lst entry can contain a bootfs command,
which specifies an alternate dataset in the pool. In this
way, the menu.lst file can contain entries for multiple root
file systems within the pool.
Kernel initialization starts when GRUB finishes loading the
boot archive and hands control over to the unix binary. At
this point, GRUB becomes inactive and no more I/O occurs
with the boot device. The Unix operating system initializes,
links in the necessary modules from the boot archive and
mounts the root file system on the real root device. At this
point, the kernel regains storage I/O, mounts additional
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file systems (see vfstab(4)), and starts various operating
system services (see smf(5)).
Failsafe Mode
A requirement of booting from a root filesystem image built
into a boot archive then remounting root onto the actual
root device is that the contents of the boot archive and the
root filesystem must be consistent. Otherwise, the proper
operation and integrity of the machine cannot be guaranteed.
The term "consistent" means that all files and modules in
the root filesystem are also present in the boot archive and
have identical contents. Since the boot strategy requires
first reading and mounting the boot archive as the first-
stage root image, all unloadable kernel modules and initial-
ization derived from the contents of the boot archive are
required to match the real root filesystem. Without such
consistency, it is possible that the system could be running
with a kernel module or parameter setting applied to the
root device before reboot, but not yet updated in the root
archive. This inconsistency could result in system instabil-
ity or data loss.
Once the root filesystem is mounted, and before relinquish-
ing the in-memory filesystem, Solaris performs a consistency
verification against the two file systems. If an incon-
sistency is detected, Solaris suspends the normal boot
sequence and falls back to failsafe mode. Correcting this
state requires the administrator take one of two steps. The
recommended procedure is to reboot to the failsafe archive
and rebuild the boot archive. This ensures that a known ker-
nel is booted and functioning for the archive rebuild pro-
cess. Alternatively, the administrator can elect to clear
the inconsistent boot archive service state and continue
system bring-up if the inconsistency is such that correct
system operation will not be impaired. See svcadm(1M).
If the boot archive service is cleared and system bring-up
is continued (the second alternative above), the system may
be running with unloadable kernel drivers or other modules
that are out-of-date with respect to the root filesystem. As
such, correct system operation may be compromised.
To ensure that the boot archive is consistent, the normal
system shutdown process, as initiated by reboot(1M) and
shutdown(1M), checks for and applies updates to the boot
archive at the conclusion of the umountall(1M) milestone.
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An update to any kernel file, driver, module or driver con-
figuration file that needs to be included in the boot
archive after the umountall service is complete will result
in a failed boot archive consistency check during the next
boot. To avoid this, it is recommended to always shut down a
machine cleanly.
If an update is required to the kernel after completion of
the umountall service, the administrator may elect to
rebuild the archive by invoking:
# bootadm update-archive
Failsafe Boot Archive
The failsafe archive can be used to boot the machine at any
time for maintenance or troubleshooting. The failsafe boot
archive is installed on the machine, sourced from the
miniroot archive. Booting the failsafe archive causes the
machine to boot using the in-memory filesystem as the root
device.
SPARC
The SPARC failsafe archive is:
/platform/`uname -i`/failsafe
...and can be booted as follows:
ok boot [device-specifier] -F failsafe
If a user wishes to boot a failsafe archive from a particu-
lar ZFS bootable dataset, this can be done as follows:
ok boot [device-specifier] -Z dataset -F failsafe
x86
The x86 failsafe archive is:
/boot/x86.miniroot-safe
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...and can be booted by selecting the Solaris failsafe item
from the GRUB menu.
OPTIONS
SPARC
The following SPARC options are supported:
-a
The boot program interprets this flag to mean ask me,
and so it prompts for the name of the standalone. The
'-a' flag is then passed to the standalone program.
-D default-file
Explicitly specify the default-file. On some systems,
boot chooses a dynamic default file, used when none is
otherwise specified. This option allows the default-file
to be explicitly set and can be useful when booting
kmdb(1) since, by default, kmdb loads the default-file
as exported by the boot program.
-F object
Boot using the named object. The object must be either
an ELF executable or bootable object containing a boot
block. The primary use is to boot the failsafe or wan-
boot boot archive.
-L
List the bootable datasets within a ZFS pool. You can
select one of the bootable datasets in the list, after
which detailed instructions for booting that dataset are
displayed. Boot the selected dataset by following the
instructions. This option is supported only when the
boot device contains a ZFS storage pool.
-V
Display verbose debugging information.
boot-flags
The boot program passes all boot-flags to file. They are
not interpreted by boot. See the kernel(1M) and kmdb(1)
manual pages for information about the options available
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with the default standalone program.
client-program-args
The boot program passes all client-program-args to file.
They are not interpreted by boot.
file
Name of a standalone program to boot. If a filename is
not explicitly specified, either on the boot command
line or in the boot-file NVRAM variable, boot chooses an
appropriate default filename.
OBP names
Specify the open boot prom designations. For example, on
Desktop SPARC based systems, the designation
/sbus/esp@0,800000/sd@3,0:a indicates a SCSI disk (sd)
at target 3, lun0 on the SCSI bus, with the esp host
adapter plugged into slot 0.
-Z dataset
Boot from the root file system in the specified ZFS
dataset.
x86
The following x86 options are supported:
-B prop=val...
One or more property-value pairs to be passed to the
kernel. Multiple property-value pairs must be separated
by a comma. Use of this option is the equivalent of the
command: eeprom prop=val. See eeprom(1M) for available
properties and valid values.
If the root file system corresponding to this menu entry
is a ZFS dataset, the menu entry needs the following
option added:
-B $ZFS-BOTFS
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System Administration Commands boot(1M)
boot-args
The boot program passes all boot-args to file. They are
not interpreted by boot. See kernel(1M) and kmdb(1) for
information about the options available with the kernel.
/platform/i86pc/kernel/$ISADIR/unix
Name of the kernel to boot. When using the kernel$
token, $ISADIR expands to amd64 on 64-bit machines, and
a null string on other machines. As a result of this
dereferencing, this path expands to the proper kernel
for the machine.
X86 BOT SEQUENCE DETAILS
After a PC-compatible machine is turned on, the system
firmware in the BIOS ROM executes a power-on self test
(POST), runs BIOS extensions in peripheral board ROMs, and
invokes software interrupt INT 19h, Bootstrap. The INT 19h
handler typically performs the standard PC-compatible boot,
which consists of trying to read the first physical sector
from the first diskette drive, or, if that fails, from the
first hard disk. The processor then jumps to the first byte
of the sector image in memory.
X86 PRIMARY BOT
The first sector on a floppy disk contains the master boot
block (GRUB stage1). The stage 1 is responsible for loading
GRUB stage2. Now GRUB is fully functional. It reads and exe-
cutes the menu file /boot/grub/menu.lst. A similar sequence
occurs for DVD or CD boot, but the master boot block loca-
tion and contents are dictated by the El Torito specifica-
tion. The El Torito boot also leads to strap.com, which in
turn loads boot.bin.
The first sector on a hard disk contains the master boot
block, which contains the master boot program and the FDISK
table, named for the PC program that maintains it. The mas-
ter boot finds the active partition in the FDISK table,
loads its first sector (GRUB stage1), and jumps to its first
byte in memory. This completes the standard PC-compatible
hard disk boot sequence. If GRUB stage1 is installed on the
master boot block (see the -m option of installgrub(1M)),
then stage2 is loaded directly from the Solaris FDISK parti-
tion regardless of the active partition.
An x86 FDISK partition for the Solaris software begins with
a one-cylinder boot slice, which contains GRUB stage1 in the
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System Administration Commands boot(1M)
first sector, the standard Solaris disk label and volume
table of contents (VTOC) in the second and third sectors,
and GRUB stage2 in the fiftieth and subsequent sectors. The
area from sector 4 to 49 might contain boot blocks for older
versions of Solaris. This makes it possible for multiple
Solaris releases on the same FDISK to coexist. When the
FDISK partition for the Solaris software is the active par-
tition, the master boot program (mboot) reads the partition
boot program in the first sector into memory and jumps to
it. It in turn reads GRUB stage2 program into memory and
jumps to it. Once the GRUB menu is displayed, the user can
choose to boot an operating system on a different partition,
a different disk, or possibly from the network.
For network booting, the supported method is Intel's Preboot
eXecution Environment (PXE) standard. When booting from the
network using PXE, the system or network adapter BIOS uses
DHCP to locate a network bootstrap program (pxegrub) on a
boot server and reads it using Trivial File Transfer Proto-
col (TFTP). The BIOS executes the pxegrub by jumping to its
first byte in memory. The pxegrub program downloads a menu
file and presents the entries to user.
X86 KERNEL STARTUP
The kernel startup process is independent of the kernel
loading process. During kernel startup, console I/O goes to
the device specified by the console property.
When booting from UFS, the root device is specified by the
bootpath property, and the root file system type is speci-
fied by the fstype property. These properties should be
setup by the Solaris Install/Upgrade process in
/boot/solaris/bootenv.rc and can be overridden with the -B
option, described above (see the eeprom(1M) man page).
When booting from ZFS, the root device is specified by a
boot parameter specified by the -B $ZFS-BOTFS parameter on
either the kernel or module line in the GRUB menu entry.
This value (as with all parameters specified by the -B
option) is passed by GRUB to the kernel.
If the console properties are not present, console I/O
defaults to screen and keyboard. The root device defaults to
ramdisk and the file system defaults to ufs.
EXAMPLES
SPARC
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System Administration Commands boot(1M)
Example 1 To Boot the Default Kernel In Single-User Interac-
tive Mode
To boot the default kernel in single-user interactive mode,
respond to the ok prompt with one of the following:
boot -as
boot disk3 -as
Example 2 Network Booting with WAN Boot-Capable PROMs
To illustrate some of the subtle repercussions of various
boot command line invocations, assume that the network-
boot-arguments are set and that net is devaliased as shown
in the commands below.
In the following command, device arguments in the device
alias are processed by the device driver. The network boot
support package processes arguments in network-boot-
arguments.
boot net
The command below results in no device arguments. The net-
work boot support package processes arguments in network-
boot-arguments.
boot net:
The command below results in no device arguments. rarp is
the only network boot support package argument. network-
boot-arguments is ignored.
boot net:rarp
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System Administration Commands boot(1M)
In the command below, the specified device arguments are
honored. The network boot support package processes argu-
ments in network-boot-arguments.
boot net:speed=100,duplex=full
Example 3 Using wanboot with Older PROMs
The command below results in the wanboot binary being loaded
from DVD or CD, at which time wanboot will perform DHCP and
then drop into its command interpreter to allow the user to
enter keys and any other necessary configuration.
boot cdrom -F wanboot -o dhcp,prompt
x86 (32-bit)
Example 4 To Boot the Default Kernel In 32-bit Single-User
Interactive Mode
To boot the default kernel in single-user interactive mode,
edit the GRUB kernel command line to read:
kernel /platform/i86pc/kernel/unix -as
x86 (64-bit Only)
Example 5 To Boot the Default Kernel In 64-bit Single-User
Interactive Mode
To boot the default kernel in single-user interactive mode,
edit the GRUB kernel command line to read:
kernel /platform/i86pc/kernel/amd64/unix -as
Example 6 Switching Between 32-bit and 64-bit Kernels on
64-bit x86 Platform
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System Administration Commands boot(1M)
To be able to boot both 32-bit and 64-bit kernels, add
entries for both kernels to /boot/grub/menu.lst, and use the
set-menu subcommand of bootadm(1M) to switch. See
bootadm(1M) for an example of the bootadm set-menu.
FILES
/platform/platform-name/ufsboot
Second-level program to boot from a disk, DVD, or CD
/etc/inittab
Table in which the initdefault state is specified
/sbin/init
Program that brings the system to the initdefault state
64-bit SPARC Only
/platform/platform-name/kernel/sparcv9/unix
Default program to boot system.
x86 Only
/boot
Directory containing boot-related files.
/boot/grub/menu.lst
Menu of bootable operating systems displayed by GRUB.
/platform/i86pc/kernel/unix
32-bit kernel.
64-bit x86 Only
/platform/i86pc/kernel/amd64/unix
64-bit kernel.
SEE ALSO
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System Administration Commands boot(1M)
kmdb(1), uname(1), bootadm(1M), eeprom(1M), init(1M),
installboot(1M), kernel(1M), monitor(1M), shutdown(1M),
svcadm(1M), umountall(1M), zpool(1M), uadmin(2), boot-
params(4), inittab(4), vfstab(4), wanboot.conf(4), filesys-
tem(5)
RFC 903, A Reverse Address Resolution Protocol,
http:/www.ietf.org/rfc/rfc903.txt
RFC 2131, Dynamic Host Configuration Protocol,
http:/www.ietf.org/rfc/rfc2131.txt
RFC 2132, DHCP Options and BOTP Vendor Extensions,
http:/www.ietf.org/rfc/rfc2132.txt
RFC 2396, Uniform Resource Identifiers (URI): Generic Syn-
tax, http:/www.ietf.org/rfc/rfc2396.txt
Sun Hardware Platform Guide
OpenBoot Command Reference Manual
WARNINGS
The boot utility is unable to determine which files can be
used as bootable programs. If the booting of a file that is
not bootable is requested, the boot utility loads it and
branches to it. What happens after that is unpredictable.
NOTES
platform-name can be found using the -i option of uname(1).
hardware-class-name can be found using the -m option of
uname(1).
The current release of the Solaris operating system does not
support machines running an UltraSPARC-I CPU.
SunOS 5.11 Last change: 2 Mar 2009 26
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