boot(1M) System Administration Commands boot(1M)NAMEboot - 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 pro‐
gram. For the purpose of this discussion, bootstrapping means the
process of loading and executing the bootable operating system. Typi‐
cally, the standalone program is the operating system kernel (see ker‐
nel(1M)), but any standalone program can be booted instead. On a SPARC-
based system, the diagnostic monitor for a machine is a good example of
a standalone program other than the operating system that can be
booted.
If the standalone is identified as a dynamically-linked executable,
boot will load the interpreter (linker/loader) as indicated by the exe‐
cutable format and then transfer control to the interpreter. If the
standalone is statically-linked, it will jump directly to the stand‐
alone.
Once the kernel is loaded, it starts the UNIX system, mounts the neces‐
sary file systems (see vfstab(4)), and runs /sbin/init to bring the
system to the "initdefault" state specified in /etc/inittab. See init‐
tab(4).
SPARC Bootstrap Procedure
On SPARC based systems, the bootstrap procedure on most machines con‐
sists 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 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) command 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 ar‐
chive from the boot device.
An IP address can be obtained in one of three ways: RARP, DHCP, or man‐
ual configuration, depending on the functions available in and configu‐
ration of the PROM. Machines of the sun4u and sun4v kernel architec‐
tures have DHCP-capable PROMs.
The boot command syntax for specifying the two methods of network boot‐
ing are:
boot net:rarp
boot net:dhcp
The command:
boot net
without a rarp or dhcp specifier, invokes the default method for net‐
work booting over the network interface for which net is an alias.
The sequence of events for network booting using RARP/bootparams is
described in the following paragraphs. The sequence for DHCP follows
the RARP/bootparams description.
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 inetboot. Subsequent requests will be sent to the server
that initially answered the first block request. After loading, inet‐
boot will also use reverse ARP to fetch its IP address, then broadcast
bootparams RPC calls (see bootparams(4)) to locate configuration infor‐
mation 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 broadcasts the hard‐
ware address and kernel architecture and requests an IP address, boot
parameters, and network configuration 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 HTTP 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 fur‐
ther DHCP activities.
If the file to be loaded is an HTTP URL, the PROM will use HTTP 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 pro‐
ceeding 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 executing, it determines
whether sufficient information is available to it to allow it to pro‐
ceed. If any necessary information 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 neces‐
sary information, it loads the boot loader into memory by means of
HTTP. If an encryption key has been installed on the client, wanboot
will verify the boot 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
HTTP or secure HTTP. If the former, and if the client has been config‐
ured with an HMAC SHA-1 key, the boot loader will perform an integrity
check of the root file system. 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
boot_logger URL by means of the wanboot.conf(4) file, wanboot will
periodically log its progress.
Not all PROMs are capable of consuming URLs. You can determine 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.
<cmd>
One of the interpreter commands listed below.
...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-pro‐
gram-args of "-o prompt" when booting. Input consists of single com‐
mands or assignments, or a comma-separated list of commands or assign‐
ments. 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 ASCII string or hex ASCII)
hostname
hostname to request in DHCP transactions (ASCII)
http-proxy
HTTP proxy server specification (IPADDR[:PORT])
The key names are:
3des
the triple DES encryption key (48 hex ASCII characters)
aes
the AES encryption key (32 hex ASCII characters)
sha1
the HMAC SHA-1 signature key (40 hex ASCII 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.
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.
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 plat‐
form-dependent search path. This path is guaranteed to contain /plat‐
form/platform-name. Many SPARC platforms next search the platform-spe‐
cific path entry /platform/hardware-class-name. See filesystem(5). If
the pathname is absolute, boot will use the specified path. The 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 otherwise speci‐
fied, for example, by the boot-file NVRAM variable, boot chooses an
appropriate default file to load based on what software is installed on
the system and the capabilities 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 sys‐
tem. A storage pool can contain multiple bootable datasets (that is,
root file systems). Therefore, when booting from ZFS, it is not suffi‐
cient to specify a boot device. One must also identify a root file sys‐
tem within the pool that was identified by the boot device. By default,
the dataset selected for booting is the one identified 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 con‐
tained 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 previous section.
The initialization of the kernel continues by loading necessary 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 typ‐
ically 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 argu‐
ments. (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.
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 appropri‐
ate default based upon the system 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 circumstances.
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 kernel.
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 production 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 processed by the package:
[protocol,] [key=value,]*
All arguments are optional and can appear in any order. Commas 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 configuration information provided by a DHCP server
for those parameters.
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
http-proxy
HTTP proxy server specification (IPADDR[: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 pack‐
age 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-argu‐
ments.
Arguments specified in network-boot-arguments will be processed 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 argu‐
ments are specified in the positional parameter syntax currently sup‐
ported, 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 of the server pro‐
viding 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 nota‐
tion) 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 RRQ is unicast to the server if one is specified as an argu‐
ment or in the DHCP response. Otherwise, the TFTP RRQ is broadcast.
file specifies the file to be loaded by TFTP from the TFTP server, or
the URL if using HTTP. The use of HTTP is triggered 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 ASCII hexadeci‐
mal 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 constructed 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 HTTP server must be
specified as an IP address (in standard IPv4 dotted-decimal notation).
The optional port number is specified in decimal. If a port is not
specified, port 80 (decimal) is implied.
The URL presented must be "safe-encoded", that is, the package does not
apply escape encodings to the URL presented. URLs containing commas
must be presented as a quoted string. Quoting URLs is optional other‐
wise.
host-ip specifies the IP address (in standard IPv4 dotted-decimal nota‐
tion) 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 notation) is the
subnet mask on the client's network. If the subnet mask is not provided
(either by means of this argument 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 ASCII hexadecimal representation of the identifier, or
o a quoted string
Thus, client-id="openboot" and client-id=6f70656e626f6f74 both repre‐
sent a DHCP client identifier of 6F70656E626F6F74.
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 ASCII 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 subnet 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 precedence over
any other DHCP mechanism of specifying identifiers.
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 charac‐
ters.
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.
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 concep‐
tually distinct phases, kernel loading and kernel initialization. Ker‐
nel 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 network
adapter, the BIOS can also download the pxegrub binary from a network
boot server. Once GRUB is located, it executes a command in a menu to
load the unix kernel and a pre-constructed boot archive containing ker‐
nel 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 ar‐
chive 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 file
systems (see vfstab(4)), and starts various operating system services
(see smf(5)).
Enabling Automatic Rebooting (x86)
The Solaris operating system supports an smf(5) property that enables a
system to automatically reboot from the current boot device, to recover
from conditions such as an out-of-date boot archive.
The service svc:/system/boot-config:default contains the boolean prop‐
erty auto-reboot-safe, which is set to false by default. Setting it to
true communicates that both the system's BIOS and default GRUB menu
entry are set to boot from the current boot device. The value of this
property can be changed using svccfg(1M) and svcadm(1M). For example,
to set auto-reboot-safe to enable automatic rebooting, enter a command
such as:
example# svccfg -s svc:/system/boot-config:default \
setprop config/auto-reboot-safe = true
Most systems are configured for automatic reboot from the current boot
device. However, in some instances, automatic rebooting to an unknown
operating system might produce undesirable results. For these
instances, the auto-reboot-safe property allows you to specify the
behavior you want.
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 consis‐
tent. Otherwise, the proper operation and integrity of the machine can‐
not 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 con‐
tents. Since the boot strategy requires first reading and mounting the
boot archive as the first-stage root image, all unloadable kernel mod‐
ules and initialization derived from the contents of the boot archive
are required to match the real root filesystem. Without such consis‐
tency, 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 instability or data loss.
Once the root filesystem is mounted, and before relinquishing the in-
memory filesystem, Solaris performs a consistency verification against
the two file systems. If an inconsistency 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 recom‐
mended procedure is to reboot to the failsafe archive and rebuild the
boot archive. This ensures that a known kernel is booted and function‐
ing for the archive rebuild process. Alternatively, the administrator
can elect to clear the inconsistent boot archive service state and con‐
tinue 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 unload‐
able kernel drivers or other modules that are out-of-date with respect
to the root filesystem. As such, correct system operation may be com‐
promised.
To ensure that the boot archive is consistent, the normal system shut‐
down process, as initiated by reboot(1M) and shutdown(1M), checks for
and applies updates to the boot archive at the conclusion of the umoun‐
tall(1M) milestone.
An update to any kernel file, driver, module or driver configuration
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 umoun‐
tall 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 particular 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
...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 use‐
ful 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 exe‐
cutable or bootable object containing a boot block. The primary use
is to boot the failsafe or wanboot 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 instruc‐
tions 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 inter‐
preted by boot. See the kernel(1M) and kmdb(1) manual pages for
information about the options available 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 explic‐
itly 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. Multi‐
ple property-value pairs must be separated by a comma. Use of this
option is the equivalent of the command: eeprom prop=val. See eep‐
rom(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 $ZFS-BOOTFS
boot-args
The boot program passes all boot-args to file. They are not inter‐
preted by boot. See kernel(1M) and kmdb(1) for information about
the options available with the kernel.
/platform/i86pc/kernel/$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 BOOT 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, Boot‐
strap. The INT 19h handler typically performs the standard PC-compati‐
ble 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 BOOT
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 executes the menu file
/boot/grub/menu.lst. A similar sequence occurs for DVD or CD boot, but
the master boot block location and contents are dictated by the El
Torito specification. 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 master 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 partition regardless of the active par‐
tition.
An x86 FDISK partition for the Solaris software begins with a one-
cylinder boot slice, which contains GRUB stage1 in the 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 sub‐
sequent 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 partition, the master boot pro‐
gram (mboot) reads the partition boot program in the first sector into
memory and jumps to it. It in turn reads GRUB stage2 program into mem‐
ory and jumps to it. Once the GRUB menu is displayed, the user can
choose to boot an operating system on a different partition, a differ‐
ent 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 boot‐
strap program (pxegrub) on a boot server and reads it using Trivial
File Transfer Protocol (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 speci‐
fied by the console property.
When booting from UFS, the root device is specified by the bootpath
property, and the root file system type is specified by the fstype
property. These properties should be setup by the Solaris
Install/Upgrade process in /boot/solaris/bootenv.rc and can be overrid‐
den 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-BOOTFS parameter on either the kernel or mod‐
ule 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
Example 1 To Boot the Default Kernel In Single-User Interactive 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 pro‐
cessed 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 network boot sup‐
port package processes arguments in network-boot-arguments.
boot net:
The command below results in no device arguments. rarp is the only net‐
work boot support package argument. network-boot-arguments is ignored.
boot net:rarp
In the command below, the specified device arguments are honored. The
network boot support package processes arguments in network-boot-argu‐
ments.
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 nec‐
essary 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
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 ALSOkmdb(1), uname(1), bootadm(1M), eeprom(1M), init(1M), installboot(1M),
kernel(1M), monitor(1M), shutdown(1M), svcadm(1M), svccfg(1M), umoun‐
tall(1M), zpool(1M), uadmin(2), bootparams(4), inittab(4), vfstab(4),
wanboot.conf(4), attributes(5), filesystem(5), smf(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 BOOTP Vendor Extensions,
http://www.ietf.org/rfc/rfc2132.txt
RFC 2396, Uniform Resource Identifiers (URI): Generic Syntax,
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 5.10 16 May 2011 boot(1M)
