BOOT_SPARC(8) BSD System Manager's Manual BOOT_SPARC(8)
boot_sparc - sparc system bootstrapping procedures
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.
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 CD-ROM ("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 com-
patibility mode (in which case it shows a simple ">" prompt), but this is
essentially useless. However, by default the ROM runs in old-mode; 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 al-
ways start in new-mode:
ok setenv sunmon-compat? false
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.
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 vari-
able. To change the default so that OpenBSD will be loaded, type the fol-
lowing:
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.
Version 2 OpenBOOT PROM will look for a bootloader on the device speci-
fied 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.
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 Disable loading debugging symbols; use for example with too
large kernels.
-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.
Proper use of these options seems to be something along these lines:
ok boot disk /bsd -a
Boot device: /iommu/sbus/espdma@f,400000/esp@f,800000/sd@3,0
File and args: /bsd -a
>> MirBSD BOOT 2.2
device[/iommu@f,.../sd@3,0:a]: just press Enter
boot: /bsd
Booting /bsd @ 0x4000
Apparently, you merely need to acknowledge the boot device, while you
have to re-enter the kernel name without the boot flags (here -a).
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 config-
ured 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.
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 pro-
gress by typing go on an OpenBOOT PROM, or c on an old-style PROM to re-
turn to ddb, and then cont to return to the system.
/bsd default system kernel
/bsd.rd standalone installation kernel, suitable for disaster
recovery
/usr/mdec/bootxx primary bootstrap for "ffs" filesystem
/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)
MirBSD #10-current April 28, 2018 1