[Q] DUAL BOOT UBUNTU And JELLY BEAN AND GUIDE

Check out http://forum.xda-developers.com/show....php?t=2011403
It's already working.

Finally my version of dual-booting Android and Ubuntu is working too! It seems I was almost there when I had the bootloops when trying to boot Android.

It's been a lot of trial-and-error, but as far as I see these were the important steps which made my Nexus 7 dual-boot Android/Ubuntu. Try them at you own risk:

Start with updating to 4.2 and unlocking. Maybe 4.2 isn't essential, but it should be something for which you have the boot image.
Flash a custom recovery using fastboot, boot it and mount /data
Extract rootfs.tar.gz from the Ubuntu rootfs.img (using simg2img to convert it to ext4 and mounting the ext4 image as a loop filesystem)
Copy rootfs.tar.gz to /data
Reboot to bootloader
Flash the Ubuntu boot.img to recovery using fastboot.
Start recovery. Ubuntu will now install.
(It seems the Ubuntu install touches the boot partition at this point, making it unable to boot Android.)
Reboot to bootloader.
Flash the original boot image (mine was 4.2) to boot using fastboot.

Now enjoy dual boot! Normal boot will start Android, recovery boot will start Ubuntu.

There may be an easier way to do this, but this is more or less what worked for me.

awesome! you mind making some kind of easier or video tutorial for those that arent reallysure about what you mean? also, with the both OS on the tab, is there any issues with it sharing the same user partition? thanks.

I think I know how to make this process more simple. Maybe both the custom recovery and the simg2img conversion can be avoided, if the remaining steps are rearranged a bit. Once I try it (and if it works) I'll try to make a more user-friendly tutorial.

I tried playing around with both OS'es today and everything seems to work like it would in single boot Android or Ubuntu, so they seem to co-exist quite well once installed. But I'd like to know why Android on boot breaks when installing Ubuntu to recovery, so boot has to be re-installed. If the Ubuntu installation is trying to write something to its own boot image I'd like to redirect it to the new location in recovery.

The Ubuntu installer carries out the following commands in this order:

fastboot erase boot
fastboot flash boot ./boot.img
fastboot erase userdata
fastboot flash userdata ./rootfs.img
fastboot reboot

I guess that changing the first one to replace boot with recovery might fix the issue.

What's the deal with userdata then? From Android does one see the Ubuntu filesystem? /me goes to read exactly what the partitions are used for.


Ah, what I've said above isn't so important, it's what the on-device setup does that's important. /me goes back to sleep

Right. I did a fresh install of Ubuntu now. It's boring to watch the screen as Ubuntu is installed - no fancy animated presentation of the blessings of this new OS, like we usually get at a time like this. But after maybe 10 minutes, right at the end of the install, I noticed it wrote something about flashing initrd to mmcblk0p2. When I was back in Android I checked /dev/block/platform/.../by-name/ and saw mmcblk0p2 is marked LNX, so at the end of the install Ubuntu flashes a new boot image! It doesn't seem to work, since I get bootloops when trying to boot normally afterwards, but still I'd like to find where in the Ubuntu install process this is done.

The installation boot image (which I flash to recovery instead) starts up Ubuntu just fine, so there's no need for flashing a new boot at that time, but maybe the new boot is better or I may break Android if updating the Ubuntu kernel?

---------- Post added at 02:22 AM ---------- Previous post was at 01:48 AM ----------

Here's a less complicated procedure for getting dual boot Android/Ubuntu. This will erase your data, void your warranty etc. It might even blow up your device and curdle the milk in your fridge. It worked OK for me, but now you've been warned!

Start with updating to 4.2.1 and unlocking. 4.2.1 isn't essential, but it should be something for which you have the boot image.

Download the Ubuntu boot and root files using the Ubuntu installer, but don't let it install.

Flash Ubuntu
Start recovery. Ubuntu will now install.
(The Ubuntu install flashes the boot partition at this point, making it unable to boot Android.)

Reboot to bootloader.

Flash the original boot image (mine was 4.2.1) to boot using fastboot.
As before, normal boot will start Android, recovery boot will start Ubuntu.

If the Ubuntu install should want to update its initrd at some later time, it will probably flash to boot instead of to recovery. That has to be looked into.
Edit: I found the culprit. In /usr/share/flash-kernel/functions the last partition with a working boot image is picked for flashing the new boot image. Since recovery is in mmcblk0p1 and boot is in mmcblk0p2 the latter is chosen.
And since the abootimg call only updates the boot image instead of creating a new one, a mix of Android and Ubuntu is created which explains why I got bootloops.
Now I just have to figure out how to modify the script so it picks the right partition. Maybe abootimg can determine if the existing image is Android or Ubuntu? But I'll save that fun for another night

Edit again: This procedure no longer works. I tried installing a new 13.04 Ubuntu but now the installation boot.img won't serve as an ordinary boot. It stops if the initial tarball has already been unpacked. So the script above must be modified and run so mmcblk0p1 is updated with an ordinary boot image.

Just discovered this, finished the entire process and am now just waiting for ubuntu to boot.

... But man its been several minute on the "Preparing the root filesystem, please, this will take a few minutes ...." will it always take this long or am i actually stuck on some boot loop thing?...

First Boot takes a while.

Yeah I figured that out thanks.
Does anyone else have trouble setting up a Bluetooth keyboard?
The Ubuntu build still seems pretty sketch, but awesome none the less.

Take a look at the ubuntu FAQ vor read in the multiboot post. Somwhere there is a solution.