boot_sparc - sparc system bootstrapping procedures
System starts
When powered on, after a panic, or if the system is rebooted
via
reboot(8) or shutdown(8), the PROM will proceed to its initialization,
and will boot an operating system if autoboot is enabled.
Boot process description [Toc] [Back]
System boot blocks are installed near the start of the boot
disk using
the procedure described in installboot(8). The boot program
attempts to
load the kernel from the selected boot device, which must
currently be an
``sd'', ``xd'' or ``xy'' disk, or an SCSI cdrom (``cd'') or
tape drive
(``st'').
The SPARC boot ROM comes in two flavours: an ``old-style''
ROM is used in
sun4 machines, while a ``new-style'' ROM can be found on
sun4c and sun4m
models. The ``new-style'' SPARC boot ROM is a full-featured
Forth system
with emacs key bindings. It can be put in ``old-style'' user-interface
compatibility mode (in which case it shows a simple ``>''
prompt), but
this is essentially useless. However, by default the ROM
runs in oldmode;
to enter new-mode type ``n''. The ROM then shows a
Forth-style
``ok'' prompt. It is recommended to have the ROM always
start in its native
``new-style'' mode. Utter the following incantation in
new-mode to
force the ROM to always start in new-mode:
ok setenv sunmon-compat? false
Old-style PROM operation [Toc] [Back]
By default, the old ROM will poll for boot devices, unless
the eeprom
settings are set to specify a particular boot device. The
OpenBSD bootloader
will then look for a kernel named bsd by default, unless a different
filename has been specified in the boot command.
Refer to the ``PROM User's Manual'' for more information.
OpenBoot PROM version 1 operation [Toc] [Back]
Older OpenBOOT PROM, as well as hybrid (dual-mode) versions
operating in
compatibility mode (with the variable version2? set to
false) will look
for a bootloader and kernel filename as specified by the
boot-from variable.
To change the default so that OpenBSD will be loaded,
type the
following:
ok setenv boot-from sd(0,0,0)bsd
Replace ``sd(0,0,0)'' with the appropriate boot device if
necessary.
Autoboot is enabled by setting the auto-boot? variable to
``true'', and
is the factory default.
OpenBoot PROM version 2 operation [Toc] [Back]
Version 2 OpenBOOT PROM will look for a bootloader on the
device specified
by the boot-device variable. The OpenBSD bootloader
will then look
for a kernel named bsd by default, unless the boot-file
variable is set,
or a different filename has been specified in the boot command. To reset
this variable to its default, empty, value, type the following:
ok set-default boot-file
Autoboot is enabled by setting the auto-boot? variable to
``true'', and
is the factory default.
Boot process options [Toc] [Back]
The following options are recognized:
-a Prompt for the root filesystem and swap devices
after the devices
have been configured.
-c Enter the ``User Kernel Configuration'' mode upon startup
(see boot_config(8)).
-d Enter the debugger , ddb(4), as soon as the kernel console
has been initialized.
-s Boot the system single-user. The system will be
booted multi-user
unless this option is specified.
Abnormal system termination [Toc] [Back]
If the system crashes, it will enter the kernel debugger,
ddb(4), if it
is configured in the kernel. If the crash occurred during
initialization
and the debugger is not present or is exited, the kernel
will halt the
system. If the crash occurred during normal operation and
the debugger
is not present or is exited, the system will attempt a dump
to the configured
dump device (which will be automatically recovered
with
savecore(8) during the next multi-user boot cycle), and after the dump is
complete (successful or not) the kernel will attempt a reboot.
Accessing the PROM during runtime [Toc] [Back]
If the sysctl(8) variable ddb.console is enabled, at any
time you can
break back to the ROM by pressing the ``L1'' (also known as
the ``stop
key'') and ``a'' keys at the same time (if the console is a
serial port
the same is achieved by sending a ``break''), and entering
machine prom
at the prompt. If you do this accidentally you can continue
whatever was
in progress by typing go on an OpenBOOT PROM, or c on an
old-style PROM
to return to ddb, and then cont to return to the system.
/bsd default system kernel
/usr/mdec/bootxx primary bootstrap for ``ffs'' file system
/usr/mdec/boot secondary bootstrap (usually also installed as /boot)
ddb(4), boot_config(8), halt(8), init(8), installboot(8),
reboot(8),
savecore(8), shutdown(8)
OpenBSD 3.6 April 19, 1994
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