Gentoo on the Marvell SheevaPlug

1.  Overview

Installing Gentoo in the SheevaPlug is pretty simple. You can either use an USB mass storage device, like an USB stick or an USB HDD, or you can use an SD card.

The SheevaPlug also has 512MB of NAND(flash) storage, but unless you want to install a very small system it won't be enough for running a Gentoo installation. This is due to the portage tree, which is ~499MB. You could install Gentoo on the NAND, but you'll need to mount the portage tree using NFS or other kind of storage. Therefore, since we want a standalone system, we'll just use one of the two options mentioned above.

2.  Requirements

To be able to install Gentoo, you'll need the following:

• A Marvell Sheevaplug
• One USB storage device/One SD card
• A network connection
• An USB cable where one end is an A-mini connection(to connect it to your plug)
• A TFTP server running and in the same network as the plug

3.  Preparing to boot your plug

Overview

Before we start the installation process, we need to set up our plug's serial and install a TFTP server on our computer.

Accessing the plug's serial

For accessing the plug's serial, we need an USB cable where one end is a B-mini USB connector, which we'll connect it to the connector of the same type near the SD slot, which is located on the left side of the plug, supposing the RJ-45 and the normal USB connector are at the top. Don't plug it to your computer yet.

For the serial to work, you need to have the needed kernel driver loaded on the computer. Make sure you have it either as built-in in your kernel or as a module, if the latter, load it.

Device Drivers --->
  <*> USB support  --->
    <*> USB Serial Converter support  --->
      <*> USB FTDI Single Port Serial Driver

If you built the driver as a module and you are unable to get the ttyUSB* devices(those devices should only show up if the plug is powered on), you need to pass a few parameters when loading it:

# modprobe usbserial vendor=0x9e88 product=0x9e8f
# modprobe ftdi_sio vendor=0x9e88 product=0x9e8f

After that, you need a serial terminal emulator. You can use, for example net-misc/minicom or net-misc/picocom, configured with the following parameters:

• Serial Device: /dev/ttyUSB1
• Baudrate: 115200bps
• Databits: 8
• Parity: None
• Stopbits: 1
• Hardware Flow Control: No
• Software Flow Control: No

That configuration is also known as 115200 8N1.

After configuring your favorite serial terminal emulator, plug your Sheevaplug and you should see some boot information.

Installing a TFTP server

Since we need a TFTP server so our plug can get the kernel and the initramfs of the installation environment, we'll install one. Remember that the TFTP server has to be in a computer that its in the same network as the plug. I used net-misc/tftp-hpa.

# emerge tftp-hpa

Specify the directory where the kernel and initramfs files are located:

# nano -w /etc/conf.d/in.tftpd

(Set the variable accordingly)
INTFTPD_PATH="/tftproot/"

Now, start the TFTP server:

# /etc/init.d/in.tftpd start

Now we have our TFTP server running, next, download the files needed for booting your plug

Getting the kernel and the initramfs

Now we'll download the kernel and the initramfs:

(Replace with your directory)
# cd /tftproot
# wget http://dev.gentoo.org/~armin76/arm/sheevaplug/install/uImage_kwplug
# wget http://dev.gentoo.org/~armin76/arm/sheevaplug/install/sheevaplug.initramfs

4.  Booting the installation environment

For booting our plug using the files from the TFTP server, we need to set up some variables on U-Boot.

Once you have your serial terminal emulator working, start or reboot your plug, so you can see the boot process and break into the U-Boot console.

[snip]
512 MB

CPU : Marvell Feroceon (Rev 1)

Streaming disabled
Write allocate disabled


USB 0: host mode
PEX 0: interface detected no Link.
Net:   egiga0 [PRIME], egiga1
Hit any key to stop autoboot:  3
(Hit any key before it gets to 0)

Marvell>>

Once we get the Marvell>> prompt, it means we're in U-Boot's console.

You need to give to the plug the IP address of the tftpserver and the IP for the device itself:

Marvell>> setenv ipaddr 192.168.0.3 (replace with the IP you want the plug to have)
Marvell>> setenv serverip 192.168.0.1 (replace with the TFTP server IP)

For booting kernels from the mainline kernel, we need the following variables set:

Marvell>> setenv arcNumber 2097
Marvell>> setenv mainlineLinux yes
Marvell>> saveenv
Saving Environment to NAND...
Erasing Nand...Writing to Nand... done
Marvell>> reset

Now we'll tftpboot our plug:

Marvell>> tftpboot 0x8000000 sheevaplug.initramfs
Marvell>> tftpboot 0x2000000 uImage_kwplug
Marvell>> setenv bootargs console=ttyS0,115200 root=/dev/ram rw
Marvell>> bootm 0x2000000 0x8000000

Once it has booted, you can now proceed to the installation chapter.

5.  Installing Gentoo

Overview

The installation on this device is more or less the same as any other kind of machine.

So please read and follow the ARM Handbook from the beginning, just skip the 10th chapter, as its irrelevant for our machine. I'll just explain what we have to do differently. Please read below first so you know when you have to go back to this document during the installation.

Partitions

As I already explained, we don't need a boot partition, although you can create it anyway if you want to have your kernels and initramfs separated from the main partition.

Stages information

Here's some information about the stages.

• Architecture: arm
• Subarchitecture: armv5tel
• CHOST: armv5tel-softfloat-linux-gnueabi
• Profile: default/linux/arm/10.0

We'll be using the new EABI, also called gnueabi, instead of the old ABI. That is armel on Debian. There's no exact reason for why we should use this EABI and not the old one, apart that this one is better than the old.

Therefore, we need an armv5tel-softfloat-linux-gnueabi stage3, available under the releases/arm/autobuilds directory in your favourite mirror

Configuring and installing the kernel

The SheevaPlug is supported in the mainline kernel since 2.6.30-rc1.

First, we need the following packages for compiling our own kernel:

# emerge u-boot-tools

Now, let's emerge vanilla-sources:

# emerge '>=sys-kernel/vanilla-sources-2.6.30_rc1'

After that we can start configuring our kernel:

# cd /usr/src/linux
# make kirkwood_defconfig menuconfig

Once you've configured it, you need to run the following command for creating an U-Boot kernel image and the kernel modules:

# make uImage && make modules_install

Now we flash the kernel to the flash partition, mtdblock1.

# cat arch/arm/boot/uImage > /dev/mtdblock1

Enabling SSH access

Now we add sshd to the startup of our system so we can access it when we boot into our new system.

# rc-update add sshd default

Enabling serial console access

By default the ttyS0 port is configured to 9600bps. Thats okay if you have your client configured to 9600bps, however, as you probably know, the serial port on the machine is configured at 115200bps. So probably you want to change the speed of the port in the ttyS0 line of the /etc/inittab file:

# nano -w /etc/inittab

(Uncomment the line and change 9600 with 115200)
s0:12345:respawn:/sbin/agetty 115200 ttyS0 vt100

Finishing the installation

This is pretty much all the installation, read all the recommendations of the handbook, and remember to change the root password and/or create some users.

6.  Booting to our new system

Once you've finished the installation of Gentoo into your SheevaPlug, there's still something you need to do so it boots to our new system. We need to break into U-Boot console again, have a look at the section explaining it to remember how to do it.

Once you're in, type the following commands:

(Change root=/dev/sda1 by your root device/partition)
(If you're using an SD Card, the root partition will be called /dev/mmcblk0p1)
(If you're using the NAND, the root partition will be called /dev/mtdblock2, for booting from jffs2 you must add rootfstype="jffs2" to bootargs)
Marvell>> setenv bootcmd nand read 0x01000000 0x00100000 0x00400000\;setenv bootargs $(console) root=/dev/sda1 rootdelay=5\; bootm 0x01000000
Marvell>> saveenv
Saving Environment to NAND...
Erasing Nand...Writing to Nand... done
Marvell>> reset

After doing that, your plug should reboot into your new system! Have fun!

7.  References

You may find more documentation about the device itself and Linux-related on the following links:

• Openplug.org
• Openplug.org wiki
• Marvell SheevaPlug development resources

8.  Thanks

I'd like to thank Marvell since they provided us some hardware to do this porting and they've been very helpful.

The contents of this document are licensed under the Creative Commons - Attribution / Share Alike license.