en/handbook/hb-install-mips-bootloader.xml

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<sections>

<abstract>
On both Silicon Graphics machines, and on Cobalt servers, both require the use
of a bootloader to load the kernel.  This section covers setting up
arcboot/arcload (for SGI machines) and colo for Cobalt servers.
</abstract>

<version>11</version>
<date>2011-05-09</date>

<section id="sgi">
<title>Silicon Graphics Machines -- Setting Up arcload</title>
<subsection>
<title>Which one?</title>
<body>

<p>
On SGI machines, we use the <c>arcload</c> boot loader.  In previous releases,
we also provided <c>arcboot</c>, however it has been officially declared
obsolete, in favour of <c>arcload</c>.
</p>

<note>
The SGI volume header filenames are limited to 8 characters, and there may be
no more than 16 files contained in a single volume header.
</note>

</body>
</subsection>

<subsection>
<title>Installing arcload</title>
<body>

<p>
<c>arcload</c> was written for machines that require 64-bit kernels, and
therefore can't use <c>arcboot</c> (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. So, now you know what this is about, we can
proceed with the installation:
</p>

<pre caption="Merging arcload and dvhtool">
# <i>emerge arcload dvhtool</i>
</pre>

<p>
Once this has finished, you should find the <c>arcload</c> binary in
<path>/usr/lib/arcload</path>. Now, two files exist:
</p>

<ul>
  <li>
    <c>sashARCS</c>: The 32-bit binary for Indy, Indigo2 (R4k), Challenge S and
    O2 systems
  </li>
  <li>
    <c>sash64</c>: The 64-bit binary for Octane/Octane2, Origin 200/2000 and
    Indigo2 Impact systems
  </li>
</ul>

<p>
Use <c>dvhtool</c> to install the appropriate binary for your system into the
volume header:
</p>

<pre caption="Placing arcload in the volume header">
<comment>(Indy/Indigo2/Challenge S/O2 users)</comment>
# <i>dvhtool --unix-to-vh /usr/lib/arcload/sashARCS sashARCS</i>

<comment>(Indigo2 Impact/Octane/Octane2/Origin 200/Origin 2000 users)</comment>
# <i>dvhtool --unix-to-vh /usr/lib/arcload/sash64 sash64</i>
</pre>

<note>
You don't have to use the name <c>sashARCS</c> or <c>sash64</c>, unless you are
installing to the volume header of a bootable CD. For normal boot from
hard-disk, you may name them something else if you wish.
</note>

<p>
Now just use <c>dvhtool</c> to verify they are in the volume header.
</p>

<pre caption="Checking arcload is present in the volume header">
# <i>dvhtool --print-volume-directory</i>
----- directory entries -----
Entry #0, name "sash64", start 4, bytes 55859
#
</pre>

<p>
Now, the <c>arc.cf</c> file has a C-like syntax. For the full detail on how one
configures it, see the <uri
link="http://www.linux-mips.org/wiki/Arcload">arcload page on the Linux/MIPS
wiki</uri>. In short, you define a number of options, which you enable and
disable at boot time using the <c>OSLoadFilename</c> variable.
</p>

<pre caption="An example arc.cf">
<comment># ARCLoad Configuration</comment>

<comment># Some default settings...</comment>
append  "root=/dev/sda3";
append  "ro";
append  "console=ttyS0,9600";

<comment># Our main definition. ip28 may be changed if you wish.</comment>
ip28 {
        <comment># Definition for a "working" kernel</comment>
        <comment># Select this by setting OSLoadFilename="ip28(working)"</comment>
        working {
                description     "SGI Indigo2 Impact R10000\n\r";
                image system    "/working";
        }

        <comment># Definition for a "new" kernel</comment>
        <comment># Select this by setting OSLoadFilename="ip28(new)"</comment>
        new {
                description     "SGI Indigo2 Impact R10000 - Testing Kernel\n\r";
                image system    "/new";
        }

        <comment># For debugging a kernel</comment>
        <comment># Select this by setting OSLoadFilename="ip28(working,debug)"</comment>
        <comment># or OSLoadFilename="ip28(new,debug)"</comment>
        debug {
                description     "Debug console";
                append          "init=/bin/bash";
        }
}
</pre>

<p>
Starting with <c>arcload-0.5</c>, <path>arc.cf</path> and kernels may reside
either in the volume header, or on a partition. If you wish to utilise this
newer feature, you may instead place the files in your <path>/boot</path>
partition (or <path>/</path> if your boot partition is not separate).
<c>arcload</c> uses the filesystem driver code from the popular <c>grub</c>
bootloader, and thus supports the same range of filesystems.
</p>

<pre caption="Placing arc.cf and kernel in the volume header">
# <i>dvhtool --unix-to-vh arc.cf arc.cf</i>
# <i>dvhtool --unix-to-vh /usr/src/linux/vmlinux new</i>
</pre>

<p>
With this done, now all that's left is to set some options in the PROM. See the
section on <uri link="#reboot">Rebooting the System</uri>.
</p>

</body>
</subsection>

</section>

<section id="cobalt">
<title>Cobalt MicroServers -- Setting Up CoLo</title>
<subsection>
<title>Installing CoLo</title>
<body>

<p>
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.
</p>

<ul>
  <li>
    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 is
    totally out of the question.
  </li>
  <li>
    64-bit kernels are not supported by the stock firmware (although these are
    highly experimental on Cobalt machines at this time)
  </li>
  <li>
    The shell is basic at best
  </li>
</ul>

<p>
To overcome these limitations, an alternative firmware, called <uri
link="http://www.colonel-panic.org/cobalt-mips/">CoLo</uri> (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.
</p>

<note>
This guide will take you through setting up CoLo so that it is loaded by the
stock firmware. This is the only truly safe, and recommended way to set up
CoLo.
</note>

<warn>
You may, if you wish, flash it into the server, and totally replace the
original firmware -- however, you are entirely on your own in that endeavour.
Should anything go wrong, you will need to physically remove the BOOTROM and
reprogram it yourself with the stock firmware. If you are not sure how to do
this -- then <e>DO NOT</e> flash your machine. We take no responsibility for
whatever happens if you ignore this advice.
</warn>

<p>
Okay, with the warnings over now, we'll get on with installing CoLo. First,
start by emerging the package.
</p>

<pre caption="Emerging colo">
# <i>emerge colo</i>
</pre>

<p>
With that installed (I hope you read those messages ;-) you should be able to
look inside the <path>/usr/lib/colo</path> directory to find two files,
<path>colo-chain.elf</path>: the "kernel" for the stock firmware to load, and
<path>colo-rom-image.bin</path>: a ROM image for flashing into the BOOTROM. We
start by mounting /boot and dumping a compressed copy of
<path>colo-chain.elf</path> in <path>/boot</path> where the system expects it.
</p>

<pre caption="Putting CoLo in its place">
# <i>gzip -9vc /usr/lib/colo/colo-chain.elf &gt; /boot/vmlinux.gz</i>
</pre>

</body>
</subsection>

<subsection>
<title>Configuring CoLo</title>

<body>

<p>
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
<path>default.colo</path>. The syntax is fully documented in the CoLo
documentation (have a peek at
<path>/usr/share/doc/colo-X.YY/README.shell.gz</path> -- where X.YY is the
version installed), and is very simple.
</p>

<note>
Just a tip: when installing kernels, I usually create two kernel images,
<path>kernel.gz.working</path> -- a known working kernel, and
<path>kernel.gz.new</path> -- a kernel that's just been compiled. You can
either use symlinks to point to the curent "new" and "working" kernels, or just
rename the kernel images.
</note>

<pre caption="A basic default.colo">
<comment>#:CoLo:#</comment>
mount hda1
load /kernel.gz.working
execute root=/dev/sda3 ro console=ttyS0,115200
</pre>

<note>
CoLo will refuse to load a script that does not begin with the <c>#:CoLo:#</c>
line. Think of it as the equivalent of saying <c>#!/bin/sh</c> in shell
scripts.
</note>

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

<pre caption="Menu-based configuration">
<comment>#:CoLo:#</comment>

lcd "Mounting hda1"
mount hda1
select "Which Kernel?" 50 Working New

goto {menu-option}
var image-name vmlinux.gz.working
goto 3f
@var image-name vmlinux.gz.working
goto 2f
@var image-name vmlinux.gz.new

@lcd "Loading Linux" {image-name}
load /{image-name}
lcd "Booting..."
execute root=/dev/sda5 ro console=ttyS0,115200
boot
</pre>

<p>
See the documentation in <path>/usr/share/doc/colo-VERSION</path> for more
details.
</p>

</body>

</subsection>
</section>

<section>
<title>Setting up for Serial Console</title>

<subsection>
<body>

<p>
Okay, the Linux installation as it stands now, would boot fine, but assumes
you're going to be logged in at a physical terminal. On Cobalt machines, this
is particularly bad -- there's no such thing as a physical terminal.
</p>

<note>
Those who do have the luxury of a supported video chipset may skip this section
if they wish.
</note>

<p>
First, pull up an editor and hack away at <path>/etc/inittab</path>. Further
down in the file, you'll see something like this:
</p>

<pre caption="inittab Configuration">
<comment># SERIAL CONSOLE</comment>
<comment>#c0:12345:respawn:/sbin/agetty 9600 ttyS0 vt102</comment>

<comment># TERMINALS</comment>
c1:12345:respawn:/sbin/agetty 38400 tty1 linux
c2:12345:respawn:/sbin/agetty 38400 tty2 linux
c3:12345:respawn:/sbin/agetty 38400 tty3 linux
c4:12345:respawn:/sbin/agetty 38400 tty4 linux
c5:12345:respawn:/sbin/agetty 38400 tty5 linux
c6:12345:respawn:/sbin/agetty 38400 tty6 linux

<comment># What to do at the "Three Finger Salute".</comment>
ca:12345:ctrlaltdel:/sbin/shutdown -r now
</pre>

<p>
First, uncomment the <c>c0</c> line. By default, it's set to use a terminal
baud rate of 9600 bps. On Cobalt servers, you may want to change this to 115200
to match the baud rate decided by the BOOT ROM. This is how that section looks
on my machine. On a headless machine (e.g. Cobalt servers), I'll also recommend
commenting out the local terminal lines (<c>c1</c> through to <c>c6</c>) as
these have a habit of misbehaving when they can't open <path>/dev/ttyX</path>.
</p>

<pre caption="Example snippet from inittab">
<comment># SERIAL CONSOLE</comment>
c0:12345:respawn:/sbin/agetty 115200 ttyS0 vt102

<comment># TERMINALS -- These are useless on a headless qube</comment>
<comment>#c1:12345:respawn:/sbin/agetty 38400 tty1 linux</comment>
<comment>#c2:12345:respawn:/sbin/agetty 38400 tty2 linux</comment>
<comment>#c3:12345:respawn:/sbin/agetty 38400 tty3 linux</comment>
<comment>#c4:12345:respawn:/sbin/agetty 38400 tty4 linux</comment>
<comment>#c5:12345:respawn:/sbin/agetty 38400 tty5 linux</comment>
<comment>#c6:12345:respawn:/sbin/agetty 38400 tty6 linux</comment>
</pre>

<p>
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
<path>/etc/securetty</path>. 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 <c>root</c> logins.
</p>

<pre caption="Enabling root logins on serial console">
<comment>(/dev/ttyS0 -- the traditional name for the first serial port)</comment>
# <i>echo 'ttyS0' >> /etc/securetty</i>

<comment>(Lately, Linux also calls this /dev/tts/0 -- so we add this
too)</comment>
# <i>echo 'tts/0' >> /etc/securetty</i>
</pre>

</body>
</subsection>
</section>

<section id="reboot">
<title>Rebooting the System</title>
<subsection>
<body>

<p>
Exit the chrooted environment and unmount all mounted partitions. Then type in
that one magical command you have been waiting for: <c>reboot</c>.
</p>

<pre caption="Exiting the chroot, unmounting all partitions and rebooting">
# <i>exit</i>
cdimage ~# <i>cd</i>
cdimage ~# <i>umount -l /mnt/gentoo/dev{/shm,/pts,}</i>
cdimage ~# <i>umount -l /mnt/gentoo{/boot,/proc,}</i>
cdimage ~# <i>reboot</i>
</pre>

<note>
<e>Cobalt Users:</e> The rest of this section covers the setting up of the SGI
PROM so that it boots <c>arcload</c> off disk and loads
Linux.
This is not applicable to the setup of Cobalt servers. In fact, all your work
is done -- there is no configuration needed for the first boot up, you can skip
to the next section: <uri link="?part=1&amp;chap=11">Finalising your Gentoo
Installation</uri>
</note>

</body>
</subsection>
</section>
<section>
<title>Tweaking the SGI PROM</title>
<subsection>
<title>Setting generic PROM settings</title>
<body>

<p>
Now that you've installed the bootloader, you're ready to reboot the machine.
</p>

<pre caption="Rebooting">
<comment>(Exit the chroot environment)</comment>
# <i>exit</i>

<comment>(Unmount the drives)</comment>
cdimage ~# <i>umount -l /mnt/gentoo/dev{/shm,/pts,}</i>
cdimage ~# <i>umount -l /mnt/gentoo{/boot,/proc,}</i>

<comment>(Reboot)</comment>
# <i>reboot</i>
</pre>

<p>
When you are rebooted, go to the <e>System Maintenance Menu</e> and select
<e>Enter Command Monitor</e> (<c>5</c>) like you did when you netbooted the
machine.
</p>

<pre caption="Configuring the PROM to Boot Gentoo">
1) Start System
2) Install System Software
3) Run Diagnostics
4) Recover System
5) Enter Command Monitor

Option? <i>5</i>
Command Monitor. Type "exit" to return to the menu.

<comment>(Set some options for arcload)</comment>

<comment>(Provide the location of the Volume Header)</comment>
&gt;&gt; <i>setenv SystemPartition scsi(0)disk(1)rdisk(0)partition(8)</i>

<comment>(Automatically boot Gentoo)</comment>
&gt;&gt; <i>setenv AutoLoad Yes</i>

<comment>(Set the timezone)</comment>
&gt;&gt; <i>setenv TimeZone EST5EDT</i>

<comment>(Use the serial console - graphic adapter users should have "g" instead of "d1" (one))</comment>
&gt;&gt; <i>setenv console d1</i>

<comment>(Setting 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.  )</comment>
&gt;&gt; <i>setenv dbaud 9600</i>
</pre>

<p>
Now, the next settings depend on how you are booting the system.
</p>

</body>
</subsection>

<subsection>
<title>Settings for direct volume-header booting</title>
<body>

<p>
This is covered here for completeness. It's recommended that users look into
installing <c>arcload</c> instead.
</p>

<note>
This only works on the Indy, Indigo2 (R4k) and Challenge S.
</note>

<pre caption="PROM settings for booting off the volume header">
<comment>(&lt;root device&gt; = Gentoo's root partition, e.g. /dev/sda3)</comment>
&gt;&gt; <i>setenv OSLoadPartition &lt;root device&gt;</i>

<comment>(To list the available kernels, type "ls")</comment>
&gt;&gt; <i>setenv OSLoader &lt;kernel name&gt;</i>
&gt;&gt; <i>setenv OSLoadFilename &lt;kernel name&gt;</i>

<comment>(Declare the kernel parameters you want to pass)</comment>
&gt;&gt; <i>setenv OSLoadOptions &lt;kernel parameters&gt;</i>
</pre>

<p>
If you wish to try a kernel without messing with kernel parameters, you may do
so using the <c>boot -f</c> PROM command:
</p>

<pre caption="Booting without changing environment variables">
<comment>(Booting a kernel, "new", with additional options)</comment>
# <i>boot -f new root=/dev/sda3 ro</i>
</pre>

</body>
</subsection>

<subsection>
<title>Settings for arcload</title>
<body>

<p>
<c>arcload</c> uses the <c>OSLoadFilename</c> option to specify which options
to set from <path>arc.cf</path>. 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
<c>OSLoadFilename=mysys(serial)</c> pulls in the settings for the <c>mysys</c>
block, then sets further options overridden in <c>serial</c>.
</p>

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

<pre caption="PROM settings for using arcload">
<comment>(Select arcload as the bootloader:- sash64 or sashARCS)</comment>
&gt;&gt; <i>setenv OSLoader sash64</i>

<comment>(Use the "working" kernel image, defined in "ip28" section of arc.cf)</comment>
&gt;&gt; <i>setenv OSLoadFilename ip28(working)</i>
</pre>

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

<note>
Partitions are numbered starting at 0, not 1 as is the case in Linux.
</note>

<pre caption="Telling arcload where to find arc.cf">
<comment>(If you wish to load from the volume header -- use partition 8)</comment>
&gt;&gt; <i>setenv OSLoadPartition scsi(0)disk(1)rdisk(0)partition(8)</i>

<comment>(Otherwise, specify the partition and filesystem type)</comment>
&gt;&gt; <i>setenv OSLoadPartition scsi(0)disk(1)rdisk(0)partition(0)[ext2]</i>
</pre>

</body>
</subsection>

<subsection>
<title>All Done</title>
<body>

<p>
Now you're ready to enjoy Gentoo! Boot up your Gentoo installation and finish
up with <uri link="?part=1&amp;chap=11">Finalizing your Gentoo
Installation</uri>.
</p>

</body>
</subsection>
</section>
</sections>