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:
boot_file
- file name to bootstrap.
boot_osflags
- flags to pass to the secondary bootstrap program.
bootdef_dev
- default bootstrap device.
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.,
- show
*
- will display all SRM variables.
- show
b*
- will display all variables whose names begin with
b.
- show
config
- will display the complete system configuration.
- show
device
- will display all bootable devices.
- show
memory
- will display the system's memory configuration.
SRM Variables
-
-
auto_action
- What SRM will do at system startup or reset:
-
-
- boot
- automatically bootstrap the operating system.
-
-
- halt
- after POST, prompt the user on the console for commands
to execute.
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:
-
-
- a
- (automatic) multi-user mode bootstrap.
-
-
- c
- crash dump immediately after
autoconf(4), if the
NetBSD kernel is compiled with
DEBUG
; See
options(4).
-
-
- d
- break into the debugger ASAP, if the
NetBSD kernel is compiled with
DDB
or KGDB
; See
options(4).
-
-
- h
- on a reboot request from the
NetBSD kernel, halt the system instead of
rebooting.
-
-
- i
- the NetBSD secondary bootstrap
program will stop and prompt for the NetBSD
kernel file name to bootstrap.
-
-
- n
- the NetBSD kernel will ask for
the root file system's device, the kernel core dump device, and the
path to init(8).
-
-
- q
- bootstrap quietly.
-
-
- s
- single-user mode bootstrap.
-
-
- v
- bootstrap verbosely.
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:
-
-
- graphics
- use a video card for output, and a PC keyboard for
input.
-
-
- serial
- use the first serial port for console.
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
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
- /boot
- NetBSD secondary bootstrap program
(installed)
- /netbsd
- default NetBSD system kernel
- /usr/mdec/bootxx_cd9660
- primary bootstrap for “cd9660” (ISO 9660) file
system
- /usr/mdec/bootxx_ffs
- primary bootstrap for “ffs” file system
(Berkeley Fast File System)
- /usr/mdec/boot
- secondary bootstrap
- /usr/mdec/netboot
- network bootstrap
- /usr/mdec/ustarboot
- “ustar” disk and tape bootstrap
SEE ALSO
ddb(4),
alpha/mkbootimage(8),
alpha/setnetbootinfo(8),
diskless(8),
init(8),
installboot(8),
rc(8),
reboot(8),
savecore(8),
shutdown(8)
Alpha Architecture Reference Manual Third
Edition, Digital Press, Alpha
Architecture Committee, 1998.
BUGS
The device names used by
NetBSD/alpha and the SRM
Console often have no relation to each other.