NAME

boot — Alpha system bootstrapping procedures

DESCRIPTION

DEC Alpha systems can have either of two different firmware systems: ARC (a.k.a. AlphaBIOS), and SRM. Some Alpha systems have both in their flash RAM and can switch between them on command. ARC is used to bootstrap Microsoft Windows NT for Alpha. SRM is used to bootstrap OpenVMS and Ultrix. NetBSD requires SRM.

SRM can bootstrap from supported local storage devices, e.g., IDE disks or CD-ROM drives, SCSI disks or CD-ROM drives, and floppy drives. SRM can also network bootstrap via supported Ethernet interfaces, using BOOTP or MOP. The particular capabilities of SRM will vary from system to system.

When SRM boots the system, it performs a Power On Self Test (POST), probes the system busses to identify devices, and initializes them. SRM includes an x86 instruction emulator in order to run the BIOS initialization routines found in the PROM of any video cards found. In this way, most generic PCI video cards can work in Alpha systems that have PCI bus slots.

SRM then examines the state of one of several variables: auto_action. If the value of auto_action is “halt” then SRM will stop, print its prompt: “>>>” and wait for commands to be entered on the console. If the value of auto_action is “boot” then SRM will automatically bootstrap the operating system specified by various non-volatile environment variables.

SRM device names are not the same as in NetBSD, e.g., ewa0 is a DEC “tulip” Ethernet interface, dka0 is a SCSI disk on a recognized controller, dqa0 is an IDE disk on a recognized controller. The show device command will list all the devices that SRM can bootstrap from.

SRM Commands

SRM is somewhat UNIX-like in that it incorporates a simple pipe and I/O redirection, which allows command sequences like:

show config | more 
show * | more

An essential but incomplete list of SRM commands follows:

boot [-file filename] [-flags value] [device]

Boot an operating system. The default arguments for this command are taken from the SRM environment variables:

help [command]

Invoke the SRM help system.

init

Reset the SRM console, and take actions as specified by SRM variables.

set variable value [-default]

Set an SRM variable, e.g.,

set auto_action boot 
set bootdef_dev dka0 
set ewa0_mode auto

If the -default flag is used, the variable will be set to its default value.

show variable or subsystem

Show SRM variables and values, or show system state or configuration. If a wildcard is used, then all matching SRM variables are shown, e.g.,

SRM Variables

auto_action

What SRM will do at system startup or reset:

Some Alpha systems (e.g., AlphaServer 800) have a “halt” switch, which if set, will override the action of this variable, and cause SRM to stop after POST and prompt the user for commands to execute.

bootdef_dev

The default bootstrap device, e.g., dka0, dqa0, ewa0. The show device command will list the available and recognized bootable devices.

boot_file

The file to bootstrap from; this is a null string by default.

boot_osflags

The flag passed to the secondary bootstrap program, and the NetBSD kernel:

These may be used in combinations that are not mutually exclusive. These options are case-insensitive to be compatible with DEC operating systems.

console

What type of console device SRM and NetBSD will use:

Just as with Sun systems, Alpha systems will use the first serial port as a console if there is no keyboard plugged into the keyboard port, even if console is set to “graphics”.

ew*0_mode

The media and speed for DEC “tulip” Ethernet interfaces (e.g., DECchip 21040, 21140, 21143); possible values are: auto (IEEE 802.3u “Nway” negotiation), BNC, AUI, Twisted-Pair, FastFD (Fast Full Duplex).

ew*0_protocols

The protocol to use when netbooting, i.e., MOP (Maintenance Operations Protocol), or BOOTP (Bootstrap Protocol).

The Alpha SRM firmware is picky about BOOTP responses; the dhcpd.conf(5) on the server needs the

always-reply-rfc1048 on;

directive in the section for netbooting Alpha systems.

os_type

This determines which system firmware will be used after the next power-cycle, if both ARC and SRM are present in Flash RAM. This should be set to any of “UNIX”, “osf”, or “vms” to select the SRM console required for NetBSD. OSF refers to the Open Software Foundation.

After bootstrap

Once the NetBSD/alpha kernel is booted normally it initializes itself and proceeds to start the system. An automatic consistency check of the file systems takes place, and unless this fails, the system comes up to multi-user operation.

The proper way to shut the system down is with the shutdown(8) command.

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 bootstrap cycle), and after the dump is complete (successful or not) the kernel will attempt a reboot.

FILES

BUGS

The device names used by NetBSD/alpha and the SRM Console often have no relation to each other.