MILO Installations

The ARC and AlphaBIOS consoles are designed to load the Windows NT operating system. Like many other things in the Linux world, they're being used to do a job that they were never intended to do. In this case, they're used to load Linux. When you power-on an ARC/AlphaBIOS console machine, you will see the firmware initialize the hardware, and you will see a boot menu. The initialization process varies greatly by machine.

The ARC and AlphaBIOS consoles operate in essentially the same way. Both use MILO and, aside from cosmetic changes, they are identical in functionality. The keystrokes described in each section have been tested against ARC and AlphaBIOS systems, and are known to work with on-site machines. However, small differences may exist for other ARC and AlphaBIOS systems.

The Windows NT ARC/AlphaBIOS firmware is an environment in which programs (for example, the Windows NT osloader) can run and make callbacks into the firmware to perform actions.

Linux's linload.exe is a much simpler program which does just enough to load and execute MILO. linload.exe loads the appropriate image file into memory at 0x00000000 and then makes a swap-PAL PALcall to the image file. The swap is necessary because MILO, like Linux, uses a different PALcode than Windows NT. MILO relocates itself to 0x200000 and continues on through the PALcode reset entry point as before.

Setting up ARC for Installation

If you're using MILO and ARC to boot the installation program from the CD-ROM, you'll only need a MILO image disk.

If you're using MILO and ARC, but you're not booting the installation program from the CD-ROM, you'll need to make three disks:

The correct MILO disk for the class of machine onto which you are installing Red Hat Linux. The MILO disk images are located in the milo/images directory on CD 1. See Table 3-1 for which MILO image you need.
The generic installation kernel disk, made from images/generic.img on CD 1.
The RAM disk made from images/ramdisk.img on CD 1.

Please refer to Appendix A for instructions on writing image files to disks.

Once you have created these disks, boot your Alpha machine into the ARC boot menu. The first step is to set up a boot menu entry to enable MILO to be loaded from floppy disk. At the boot menu, select the option Supplementary menu.

Next, select the command: Set up the system, which takes you to the Setup Menu. From here, select the command Manage boot selection menu, which takes you to the Boot Selections Menu.

You need to add a boot command to load MILO from the floppy disk you created. Choose the command Add a boot selection.

You should see several devices listed. To select the A: drive, choose Floppy Disk 0.

	Please Note
	If you do not see an entry for the floppy drive, consult your AlphaBIOS/ARC installation manual to determine the correct method for configuring your hardware in the console.

Next, enter the name of the OS loader to use. Enter \linload.exe as the OS loader directory and name. The MILO disk you created has the linload.exe file on it, and the correct MILO for your Alpha machine class. The MILO command is always named milo on the floppy, and both files should reside in the root directory of the floppy disk.

Select the yes option when you are asked if the operating system is on the same partition as the OS loader (it is, both are in the root directory), and enter \ as the operating system root directory. As the name of the boot selection, enter something descriptive like MILO Floppy to indicate that this entry boots MILO from the floppy drive.

If prompted, select no to indicate that you do not want to start the debugger at boot time.

You should now be back in the boot selections menu. Press Esc to get back to the Boot Selections Menu. Choose the option Supplementary menu, and save changes to commit the changes to NVRAM. Once you have saved your boot entry, Esc will get you back to the boot menu and you can now attempt to boot MILO.

You should have a boot selection that looks something like this:

LOADIDENTIFIER=Linux
SYSTEMPARTITION=multi(0)disk(0)fdisk(0)
OSLOADER=multi(0)disk(0)fdisk(0)\linload.exe
OSLOADPARTITION=multi(0)disk(0)fdisk(0)\
OSLOADOPTIONS=

This boot selection enables ARC to boot into MILO from the floppy using the linload.exe OS loader.

Setting up AlphaBIOS for Installation

First, you'll need to install the latest version of AlphaBIOS, which can be obtained from Compaq's Alpha Firmware update site at

http://ftp.digital.com/pub/DEC/Alpha/firmware/

As with ARC, if you can boot from the CD-ROM, you'll only need to make a MILO disk. If your machine can't boot from the CD-ROM, you will need three disks for the MILO installation process:

The correct MILO disk for the class of machine onto which you are installing Red Hat Linux. The MILO disk images are located in the milo/images directory on CD 1. See Table 3-1 for which MILO image you need.
The generic installation kernel disk, from images/generic.img on CD 1.
The RAM disk made from images/ramdisk.img on CD 1.

Please refer to Appendix A for instructions on writing image files to disks.

Once your AlphaBIOS is at the latest revision level, you can start the installation process. Turn on the system and insert the floppy. At the opening screen, press F2 to enter setup mode. You are going to add a boot selection that allows you to boot MILO from a floppy disk. Select the following command from the menu: Utilities -> OS Selection Setup..

Press Insert to add a new operating system selection. For the Boot Name parameter, enter something like: MILO Floppy to indicate that you are loading MILO from a floppy disk. Press Tab to get to the next field. Use the DOWN-ARROW key to move through the options until the selection for Boot File is A:. Then, Tab to the next field and enter: linload.exe as the name of the OS loader.

Tab past the OS Path Load Device option, since it's irrelevant and linload.exe ignores it. Tab to the OS Path Load File option. Enter: \ for the OS Path load file. Finally, press Enter to add the selection to the boot menu.

At this point, AlphaBIOS will probably put up a big, unfriendly dialog box labeled something like Warning: Operating System Selection not valid!

Ignore this error (AlphaBIOS considers it an error whenever your OS is not Windows NT). Press Enter to continue. Press F10 to save the changes you just made, and press Enter to confirm the changes.

Press Esc twice to get back to the opening screen. Use the UP-ARROW and DOWN-ARROW keys to select the boot selection you just added, and press Enter to boot it.

AlphaBIOS will load linload.exe, which will in turn load MILO.

The MILO User Interface

Once the Windows NT firmware is running and you have the correct MILO image for your system loaded, the rest of the installation details are completely generic.

Once you boot into MILO, you get a prompt that is very familiar to the standard bash# prompt in Linux. As mentioned earlier, MILO uses native Linux device drivers; therefore, all devices in MILO are referred to in the same manner as a running Linux system (/dev/scd0 for a SCSI CD-ROM 0, /dev/hda for the first IDE device, etc.).

MILO has a very simple interface that is designed to allow you to boot a Linux kernel image, and perform some basic diagnostic functions. Typing help is a good idea, since it provides a useful summary of the commands, as follows:

MILO> help
MILO command summary: ls [-t fs] [dev:[dir]]
                  - List files in directory on device 
boot [-t fs] [dev:file] [boot string]
                 - 
Boot Linux from the specified device and file 
run [-t fs] dev:file
                 - Run the standalone program dev:file 
show             - 
Display all known devices and file systems
set VAR VALUE    -
Set the variable VAR to the specified VALUE 
unset VAR        - Delete the specified variable 
reset            - Delete all variables 
print            - Display current variable settings 
help [var]       - Print this help text
Devices are specified as: fd0, hda1, hda2, sda1... 
Use the '-t filesystem-name' option if you want 
to use anything but the default filesystem  ('ext2'). 
Use the 'show' command to show known devices and file-
systems. 
Type 'help var' for a list of variables.

	Please Note
	The bootopt command only appears on AlphaPC64 (and similar) systems. Refer to the board's documentation to find out just what it means.

Devices

Until you use a command that needs to make use of a device, no device initialization will take place. The first time you issue the show, ls, or run command, the devices within MILO will be initialized. Devices are named exactly the same way that Linux names devices. So, the first IDE drive will be called hda and its first partition will be hda1. Use the show command to show what devices are available.

Filesystems

MILO supports three filesystems: MSDOS, ext2 and ISO9660. If a device is available to it, MILO can ls, boot or run an image stored on one of these filesystems. MILO will assume ext2 as the default filesystem, and so you have to explicitly tell MILO if the filesystem is something other than ext2. All of the commands that use filenames allow you to pass the file system using the -t [filesystem] option. So, if you wanted to list the contents of a SCSI CD-ROM, you might type the following:

MILO> ls -t iso9660 scd0:

Variables

MILO contains some settable variables that help the boot process. If you are loading via Windows NT ARC or AlphaBIOS firmwares, then MILO makes use of the boot option environment variables set up by that firmware. For some systems (for example, the AlphaPC64), MILO maintains its own set of environment variables that do not change from boot to boot. These variables can be displayed with the help var command:

MILO> help var
Variables that MILO cares about: 
MEMORY_SIZE  - System memory size in megabytes 
BOOT_DEV     - Specifies the default boot device 
BOOT_FILE    - Specifies the default boot file 
BOOT_STRING  - 
Specifies the boot string to pass to the kernel 
SCSIn_HOSTID - Specifies the host id of the 
n-th SCSI controller 
PCI_LATENCY  - Specifies the PCI master device latency 
AUTOBOOT     - If set, MILO attempts to boot on powerup 
and enters command loop only on failure. 
AUTOBOOT_TIMEOUT - Seconds to wait before auto-
booting on powerup.

	Please Note
	If you set AUTOBOOT, you need to set the timeout. Setting AUTOBOOT without setting the timeout can result in your machine automatically booting after a timeout of 0 seconds, which will not allow for any user intervention in the case of errors.

Booting with MILO

The primary function of MILO is to boot the Linux kernel. To boot the installation program to use the CD-ROM (assuming the CD-ROM drive is SCSI) the command would look similar to this:

MILO> boot scd0:/kernels/generic.gz root=/dev/scd0

Note that the above command may be different for your system, because it depends upon how your system and its CD-ROM drive are set up.

To boot from the floppy, put the generic.img floppy into the floppy drive and type in the following command:

MILO> boot fd0:

The installation program should boot, and you should be able to proceed as normal. IDE CD-ROM devices use the standard IDE device references. You'll see output like the following:

available configurations: linux
(or 'halt' to return back to MILO prompt)
boot:

Type in linux and press Enter.

If needed, you'll be prompted to place the RAM disk diskette in the floppy drive, and then the installation should begin.

Installation

See to Chapter 5 for instructions on the graphical installation process. Be aware that you'll need to install MILO to the hard drive during the installation. Instructions on how to do so are included at the appropriate point during the installation.