Hey all,
I've seen a lot of people running linux on their android devices but chrooted under android and using a VNC client to make use of the chrooted install. quite messy and less than efficient IMHO, so I set out to install it natively on my Xoom
I've managed to get Debian installed on my Xoom with the only issues being no sound and no Bluetooth, this is due to the proprietary nature of the sound drivers for the Tegra, and the lack of documentation for the BCM4329 Bluetooth under linux. if anyone has any tips with these I'd love to hear them.
Anyway, since the Xoom is an android device with an unlockable bootloader from the factory this wasn't too difficult. the only issues were with the TegraFB and Touchscreen drivers. Thankfully Lilstevie from GalaxyLinux helped me out with the touchscreen driver and Robert Morell from NVidia provided a patch to Chromium for the FB which is here
http://codereview.chromium.org/6672056
(Todo: Add guide for using WIFI, upload prebuilt images)
(Update: Fixed the links)
Basically all you need to do is build a root fs and a kernel for your Debian install. this is actually quite easy. here's how..
Contents:
Requirements
Building the RootFS
Building the Kernel
Preparing the SDCard
Putting it all together
Rolling back to Android
Acknowledgements
Disclaimer
YOU DO THIS AT YOUR OWN RISK! I TAKE NO RESPONSIBILITY FOR ANY DAMAGES TO YOU, YOUR DEVICE,
YOUR COMPUTER, OR ANY OF YOUR PROPERTY OR SOMEONE ELSE'S PROPERTY
Requirements
- A Rooted Xoom with ClockWorkRecovery Installed
[*] Make sure you have a nandroid backup. you will need this to boot back into Android!
- A running install of Debian, Ubuntu might work too
- An SDCard with at least 4GB for the install, preferably separate from your main SDCard and an SDCard reader for your PC
- Android–SDK
- An Arm–linux toolchain to compile the kernel, if you're lazy like me you can just use the one that comes with the Android NDK
- This Xorg Config
- Kernel sources
- Fastboot tool
- mkbootimg
Building the RootFS
Before we do anything we'll need to get the Wifi Firmware off the default install of Android
To do this run the following commands
Code:
# adb pull /system/vendor/firmware/fw_bcm4329.bin
# adb pull /system/etc/firmware/bcm4329.hcd
MAKE A BACKUP OF YOUR SDCARD AND YOUR XOOM USING CLOCKWORK RECOVERY BEFORE CONTINUING AND KEEP IT SOMEWHERE SAFE!
Now lets install the tools you'll need to create the rootfs
Code:
# apt–get install binfmt–support qemu qemu–user–static debootstrap
Once that's done, make a directory for the rootfs to sit in until it's ready for the SDCard and start installing the debian base
Code:
# cd ~
# mkdir deb_arm
# mkdir deb_arm/boot
# sudo /usr/sbin/debootstrap ––foreign ––arch armel squeeze deb_arm/ [url]http://ftp.au.debian.org/debian[/url]
Once that's done you'll need to copy across some qemu files so you can chroot into the deb_arm folder and finish the installation of the base system
Code:
# sudo cp /usr/bin/qemu–arm–static deb_arm/usr/bin
# sudo chroot deb_arm
# export LC_ALL=C
# export LANGUAGE=C
# export LANG=C
# cd /debootstrap
# ./debootstrap ––second–stage
once that's done you'll need to edit your apt sources, to do so run the following
Code:
# echo debandroid > /etc/hostname
# echo "deb [url]http://ftp.debian.org/debian/[/url] squeeze main contrib non–free" > /etc/apt/sources.list
# apt–get update
And then install any of the apps you'll want to run on your xoom, I'd recommend at least xorg, gdm3 and gnome, so
Code:
# apt–get install xserver–xorg–video–fbdev xserver–xorg–input–evdev gdm3 gnome initramfs–tools wpa-supplicant
You may find that you get an error like the following
Errors were encountered while processing: bluez gnome–bluetooth gnome–user–share gnome–desktop–environment
If you do, it's safe to ignore this for now. you can always complete the installation of any non–critical packages on the device. it seems to be something weird with the chroot or the qemu emulation of ARM (if anyone knows a way to fix this I'd be glad to hear it!)
Once that's done, you'll not only want to set your root password but you'll want to add a standard user account too
Code:
# passwd root
# adduser liv2
# addgroup ––gid 3003 inet
# usermod –aG 3003 liv2
The addgroup and usermod are especially important, the android kernel doesn't normally allow network access to non–root accounts. so we have to add the special group then give the user access to that group (or you could compile the kernel to not use the android paranoid network settings)
Once that's done, exit out of the chroot by hitting CTRL+D and copy the xorg config to deb_arm/etc/X11/ and copy in the wireless firmware you copied at the start
Code:
# mkdir ~/deb_arm/lib/firmware
# cp ~/fw_bcm4329.bin ~/deb_arm/lib/firmware
# cp ~/bcm4329.cal ~/deb_arm/lib/firmware
Building the Kernel
For this part, make sure you've extracted the kernel sources, and the android–ndk to somewhere, in my case they've been extracted in ~/Downloads
Code:
# cd ~/Downloads/Tiamat–AOSP–Tiamat–Xoom–798572c/
# export CROSS_COMPILE=~/Downloads/android–ndk–r5b/toolchains/arm–eabi–4.4.0/prebuilt/linux–x86/bin/arm–eabi–
# export ARCH=arm
# export INSTALL_PATH=~/deb_arm/boot
# export INSTALL_MOD_PATH=~/deb_arm
# make tiamat_defconfig
# make menuconfig
Once you've got the menuconfig screen up, go to Device Drivers > Character Devices > and enable "Virtual Terminal"
go to Device Drivers > Graphics Support > Console Display Driver support > enable "Framebuffer Console Support"
once you've enabled that, exit out and save the changes
Build the kernel and prepare it for use
Code:
# make –j2
# sudo make modules_install
# sudo cp arch/arm/boot/zImage ~/deb_arm/boot
# cp System.map ~/deb_arm/boot/
# chroot ~/deb_arm
# mkinitramfs –o /boot/initrd.img.gz `ls /lib/modules`
mkinitramfs may show some warnings like "warning: can't open /etc/mtab:" and "pkg: version '2.6.36.4Tiamat_Xoom–v1.4.4–Full_Throttle' has bad syntax: invalid character in version number" but it doesn't seem to have caused any issues for me.
Preparing the SDCard
Plug your SDCard reader into your computer and insert the card, you'll then need to partition and format it so make sure you've backed up the content of the card.
Partition it so you have two partitions, the first one being a FAT32 Partition for CWR and for anything you might want to use it for under Android.
Your second partition will need to be EXT3 and big enough to fit your debian install with some room to breathe (about 4GB in my case), you can check how much space you'll need for this by running du -sh ~/deb_arm
Once you've partitioned it, format the first partition as FAT32 and the second partition as EXT3. once you've done that you should put the SDCard back in your Xoom and make a new nandroid backup just to be sure
Code:
# sudo mkfs.ext3 /dev/sdb2
# sudo mkfs.msdos /dev/sdb1
Putting it all together
First we'll mount the SDCard on your PC and copy across the Root FS
Go to the folder you unpacked mkbootimg to and copy in the boot.img from your CWR backup.
Once you've done that, follow the below steps to create the new boot.img for Debian to use
Code:
# cd ~/Downloads/mkbootimg
# cp ~/deb_arm/boot/zImage .
# cp ~/deb_arm/boot/initrd.img.gz .
# mkdir out
# ./unpackbootimg –i boot.img –o out/
# ./mkbootimg ––kernel zImage ––ramdisk initrd.img.gz ––base "`cat out/boot.img–base`" \
––cmdline "root=/dev/mmcblk0p2 console=tty0" –o newimg.img
Now reboot your Xoom into Fastboot mode and insert the SDCard, this can be done by holding power + volume up until the screen goes black, then power it back on and hold down the volume down key
Code:
# cp ~/Downloads/fastboot .
# ./fastboot flash boot newimg.img
# ./fastboot reboot
Your Xoom should now boot up into Debian, on the login screen select the accessibility options and enable on-screen keyboard to log in.
Alternatively, if you happen to have a USB-OTG adapter you can just use a keyboard and mouse to interact with the system.
Going Back to Android
To Roll back to Android, simply boot into Clockwork Recovery, go to Backup/Restore > Advanced Restore and restore boot.img only, reboot and you'll be back in Android
Acknowledgements
Lopi from the IX Project was a great help, and so was everyone from #IX
Lilstevie from @GalaxyLinux provided the Touchscreen patches
Framebuffer Patch was originally provided by Robert Morell for the Chromium Project
RootFS instructions are based on info at the Debian Wiki
