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BOOT_ALPHA(8) System Manager's Manual (alpha) BOOT_ALPHA(8)

boot_alpha
Alpha system bootstrapping procedures

When powered on, the SRM firmware will proceed to its initialization, and will boot an operating system if the auto_action variable is set to “boot” or “restart”, or will wait for interactive commands if set to “halt”.

After a panic, or if the system is rebooted via reboot(8) or shutdown(8), the SRM console will only restart the system if the auto_action variable is set to “boot”.

The SRM console will attempt to boot a kernel named from the boot_file environment variable, on the device listed in the bootdef_dev variable. A list of the recognized SRM devices can be obtained with the command show dev at the SRM prompt. If the boot_file variable is not set or empty, /bsd will be used by default.
The kernel will be passed the options listed in the boot_osflags variable. Option letters are case insensitive. The following option letters are recognized:
Boot the system multi-user. This is the default behaviour of the kernel if no flags are specified.
Enter the debugger, ddb(4), as soon as the kernel console has been initialized.
Enter the “User Kernel Configuration” mode upon startup (boot_config(8)).
Create a kernel crash dump immediately after the devices have been configured. This option is only available on kernels compiled with “option DEBUG”.
On the next system reboot, always halt the system, even if a reboot is required.
Prompt for the root filesystem device after the devices have been configured.
Boot the system single-user.

In case of system crashes, the kernel will usually enter the kernel debugger, ddb(4), unless it is not present in the kernel, or it is disabled via the ddb.panic sysctl. Upon leaving ddb, or if ddb was not entered, the kernel will halt the system if it was still in device configuration phase, or attempt a dump to the configured dump device, if possible. The crash dump will then be recovered by savecore(8) during the next multi-user boot cycle. It is also possible to force other behaviours from ddb.

/bsd
default system kernel
/bsd.rd
standalone installation kernel, suitable for disaster recovery
/usr/mdec/bootxx
primary bootstrap for “ffs” file system
/usr/mdec/boot
secondary bootstrap (usually also installed as /boot)
/usr/mdec/netboot
network bootstrap

ddb(4), boot_config(8), halt(8), init(8), installboot(8), reboot(8), savecore(8), setnetbootinfo(8), shutdown(8)
Alpha Architecture Reference Manual Third Edition, Digital Press, Alpha Architecture Committee, 1998.

The device names used by OpenBSD/alpha and the SRM Console often have no relation to each other.
January 3, 2010 OpenBSD-current