Handbook:MIPS/Blocks/Bootloader

arcload for Silicon Graphics machines
arcload was written for machines that require 64-bit kernels, and therefore can't use arcboot (which can't easily be compiled as a 64-bit binary). It also works around peculiarities that arise when loading kernels directly from the volume header. Let's proceed with the installation:

Once this has finished, find the arcload binary inside. Now, two files exist:
 * : The 32-bit binary for Indy, Indigo2 (R4k), Challenge S and O2 systems
 * : The 64-bit binary for Octane/Octane2, Origin 200/2000 and Indigo2 Impact systems

Use  to install the appropriate binary for the system into the volume header:

For Indy/Indigo2/Challenge S/O2 users:

For Indigo2 Impact/Octane/Octane2/Origin 200/Origin 2000 users:

Now just use  to verify they are in the volume header:

The file has a C-like syntax. For the full detail on how one configures it, see the arcload page on the Linux/MIPS wiki. In short, define a number of options, which are enabled and disabled at boot time using the OSLoadFilename variable.

Starting with arcload-0.5, arc.cf and kernels may reside either in the volume header, or on a partition. To utilize this newer feature, place the files in the partition (or  if the boot partition is not separate). arcload uses the filesystem driver code from the popular grub bootloader, and thus supports the same range of filesystems.

Installing CoLo
On Cobalt servers, these machines have a much less capable firmware installed on chip. The Cobalt BOOTROM is primitive, by comparison to the SGI PROM, and has a number of serious limitations.
 * There's a 675kB (approximate) limit on kernels. The current size of Linux 2.4 makes it nearly impossible to make a kernel this size. Linux 2.6 and 3.x is totally out of the question.
 * 64-bit kernels are not supported by the stock firmware (although these are highly experimental on Cobalt machines at this time)
 * The shell is basic at best

To overcome these limitations, an alternative firmware, called CoLo (Cobalt Loader) was developed. This is a BOOTROM image that can either be flashed into the chip inside the Cobalt server, or loaded from the existing firmware.

Let's get on with installing CoLo. First, start by emerging the package.

With that installed, take a look inside the directory to find two files:
 * (the "kernel" for the stock firmware to load), and
 * (a ROM image for flashing into the BOOTROM)

We start by mounting and dumping a compressed copy of  in  where the system expects it.

Configuring CoLo
Now, when the system first boots up, it'll load CoLo which will spit up a menu on the back LCD. The first option (and default that is assumed after roughly 5 seconds) is to boot to the hard disk. The system would then attempt to mount the first Linux partition it finds, and run the script default.colo. The syntax is fully documented in the CoLo documentation (have a peek at -- where X.YY is the version installed), and is very simple.

It is also possible to ask a question, such as which kernel & configuration to boot, with a default timeout. The following configuration does exactly this, asks the user which kernel they wish to use, and executes the chosen image. vmlinux.gz.new and vmlinux.gz.working may be actual kernel images, or just symlinks pointing to the kernel images on that disk. The 50 argument to select specifies that it should proceed with the first option ("Working") after 50/10 seconds.

See the documentation in for more details.

Setting up for serial console
Okay, the Linux installation as it stands now, would boot fine, but assumes the user will be logged in at a physical terminal. On Cobalt machines, this is particularly bad -- there's no such thing as a physical terminal.

First, pull up an editor and hack away at. Further down in the file, notice the following:

First, uncomment the c0 line. By default, it's set to use a terminal baud rate of 9600 bps. On Cobalt servers, this may be changed to 115200 to match the baud rate decided by the BOOT ROM. The following is how that section looks then. On a headless machine (e.g. Cobalt servers), we also recommend commenting out the local terminal lines (c1 through to c6) as these have a habit of misbehaving when they can't open.

Now, lastly... we have to tell the system, that the local serial port can be trusted as a secure terminal. The file we need to poke at is. It contains a list of terminals that the system trusts. We simply stick in two more lines, permitting the serial line to be used for root logins.

Lately, Linux also calls this /dev/tts/0 -- so we add this too:

Setting generic PROM settings
With the bootloader installed, after rebooting (which we will come to in a second), go to the System Maintenance Menu and select Command Monitor (5) like did initially when netbooting the system.

Provide the location of the Volume Header:

Automatically boot Gentoo:

Set the timezone:

Use the serial console - graphic adapter users should have "g" instead of "d1" (one):

Set the serial console baud rate. This is optional, 9600 is the default setting, although one may use rates up to 38400 if that is desired:

Now, the next settings depend on how the system is booted.

Settings for direct volume-header booting
Set the root device to Gentoo's root partition, such as :

To list the available kernels, type "ls".

Declare the kernel parameters to pass:

To try a kernel without messing with kernel parameters, use the boot -f PROM command:

Settings for arcload
arcload uses the OSLoadFilename option to specify which options to set from. The configuration file is essentially a script, with the top-level blocks defining boot images for different systems, and inside that, optional settings. Thus, setting OSLoadFilename=mysys(serial) pulls in the settings for the mysys block, then sets further options overridden in serial.

In the example file above, we have one system block defined, ip28 with working, new and debug options available. We define our PROM variables as so:

Select arcload as the bootloader:- sash64 or sashARCS:

Use the "working" kernel image, defined in "ip28" section of arc.cf:

Starting with arcload-0.5, files no longer need to be placed in the volume header -- they may be placed in a partition instead. To tell arcload where to look for its configuration file and kernels, one must set the OSLoadPartition PROM variable. The exact value here will depend on where the disk resides on the SCSI bus. Use the SystemPartition PROM variable as a guide -- only the partition number should need to change.

To load from the volume header -- use partition 8:

Otherwise, specify the partition and filesystem type: