Saturday, May 11, 2013

Installing Debian on Pogoplug Series V4

Here I'm basing the tools and instruction on Arch Linux. I'm using a PogoPlug Series V4 with a SamDisk Cruzer Fit 16GB flash drive which fits snuggly on the top USB 2.0 port, even with the lid closed.

I also followed the instructions by Moustafa Hassan to identify and solder the serial console pins, but chose a different connection method. I bought female-female jumper wires, extra long breakaway headers to couple the jumper wires, and USB to TTL serial cable which works out of box on Linux. Although it is possible to ssh into PogoPlug V4, having serial console access is a safety net in case I brick the Pogo.
  • Select black, green, and white wires. This will be used to make the external connection.
  • Pick a bundle of three other wires. I chose grey, purple and blue because that happen to come off next. Do not disband them. Cut these in two halves together, strip one half and save the other half for future use. Solder grey, purple, blue to GND, RX, TX respectively. You might want to glue them to the board since the solder joints come off easily.
    • Unfortunately you can't solder breakaway header to the board. The holes are not 1mm spaced, and the holes are too small.
  • Use the extra long breakaway to connect grey to black, purple to green, and blue to white. This connection will be inside the Pogo.
  • Carefully extend the black (GND), green (RX), white (TX) wires through the vent of the top cover, cap them with another set of breakaway header. These colors will be the same as the USB-TTL serial cable. Red is not used.
Hint: on Debian, adding your non-root user to the "dialout" group (logout, log back in) will allow you use the command "screen /dev/ttyUSB0 115200" without sudo. To find out exactly which group you need to add to on your distro, ls -l /dev/ttyUSB0 and look at the group of the file.

Installing Debian is significantly more work than Arch Linux, and generally requires another Linux machine to do the first stage bootstrapping.

I was going to use Multistrap to prepare a root filesystem but I changed that plan. Since I already have serial console and can TFTP boot anything I want, I can now TFTP boot and use the interactive Debian Installer. After interactively installing, the plan is to manually configure the bootloader using Arch Linux's U-Boot which has USB support.

To boot the Debian Installer, I need to do this one time setup at the U-Boot prompt to make mainline kernel boot on PogoPlug which is an unrecognized device. I found this information at the Plug Computer Forum.
setenv mainlineLinux yes
setenv arcNumber 2097
saveenv
reset
Correction: When using arcNumber 2097 (SheevaPlug), USB3 is not working because PCIe is not initialized, but GigE is working. When using arcNumber 1681 (RD-88F6192-NAS), USB3 works but not GigE. For proper Pogoplug V4 support, one has to build a Debian kernel with the archlinuxarm.patch.
Unfortunately, setting mainlineLinux=yes will prevent the Pogo's built-in Linux kernel from booting, so you'll have to set mainlineLinux=no if you want it back.

And then, following Debian installer for plug computer instructions, after downloading the SheevaPlug installer files to TFTP as debian/uImage and debian/uInitrd, I could boot d-i over TFTP like this:
setenv bootargs console=ttyS0,115200n8 base-installer/initramfs-tools/driver-policy=most
tftp 0x00800000 debian/uImage
tftp 0x01100000 debian/uInitrd
bootm 0x00800000 0x01100000
I installed Debian. The installer finished without requring swap space which is impressive considering that there is only 128MB of main memory. However, to get Debian to boot, I had to boot into PogoPlug Linux first and run ppv4-install.sh. First boot into U-boot:
setenv mainlinuxLinux no
saveenv
reset
Boot into PogoPlug Linux, download ppv4-install.sh and run it. But I need to make more adjustments before Debian can boot. Boot into U-Boot again and run:
setenv mainlinuxLinux yes
setenv alarm_usb 'ext2load usb 0:1 0x800000 /boot/uImage; ext2load usb 0:1 0x1100000 /boot/uInitrd; run alarm_which; run alarm_args; bootm 0x800000 0x1100000'
saveenv
reset
The reason is that ArchLinux boot script only loads the kernel but not the initramfs. If you boot from SATA/IDE, then make the analogous change to alarm_ide also. Debian should now boot normally.
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