HOWTO

hi guys!
finally we got a stable version of this hack.
follow this article for got any linux distro on your TF201 ;)
a special thanks to Smasher816, he help me so much with the "GUI" ;)

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prerequisites

This guide requires the Jelly Bean bootloader from ASUS, and will assume you already have installed it.
WARNING: if not, follow this guide before upgrading your TF201.
WARNING: for now only stock android works. custom "roms" kernels need to be patched. i'll post them here ASAP.
NOTE: in android /dev/mmcblk0p8 is /dev/block/mmcblk0p8 and it's mounted over /data
NOTE: your browser can add an extensions to the downloaded files, if yes remove them.
ERROR: sorry for my doggish english :( any suggestion/correction is appreciated
ERROR: ubuntu does not work now, we are debugging this.

downloads

• 3.1.10 kernel for 'any' distro - zImage
• root_chooser initrd -  root_chooser
• android stock kernel with kexec patch - android_kernel
• android stock initramfs - android_initrd
• files for any linux distro - root_patch.tar.gz
• gentoo specific config files - gentoo.tar.gz

step 1

install a linux distro somewhere

pick up an arm root FS of your prefered linux distro.
here you are some links:

the standard way is to extract the tarball to the root of the microsd or the USB stick.
ensure that the partition used is an ext2/ext3/ext4 filesystem.
thanks to root_choooser you can also have your distro inside a disk image or into a subdirectory of another device ( like the internal mmc ).
for extract a tarball you have to change the current directory to the root of your new linux system ( the USB stick for example ). then if the tarball ends with "gz":

tar -xzf /path/to/the/downloaded/tarball.tar.gz

else if ends with "bz" or "bz2":

tar -xjf /path/to/the/downloaded/tarball.tar.bz

now you have to configure it according to your chosen distro.

step 2

apply the root_patch

after you had set your distro you have to apply a root patch.

the root_patch is a distro-independent tarball that contains firmware, kernel modules and an alsa configuration file.

you have to change directory where you have extracted the previous tarball.

then extract the root_patch as follow:

tar -xzpf /path/to/root_patch.tar.gz

after this you should apply a distro-related patch. this is needed since any distro has it's own way to handle config files and modules options.
lets say that you have gentoo. always from the root of your distro you have to run this:

tar -xzpf /path/to/gentoo.tar.gz

step 3

configure kernel_chooser

you have to configure kernel_chooser before flashing it.
kernel_chooser read every file inside the /data/.kernel.d directory and parse it as follow:

NAME/DESCRIPTION
blkdev:kernel:initrd
CMDLINE

where:

• NAME/DESCRIPTION is an optional description for the boot entry
• blkdev is the device where other files are sotred
• kernel is the kernel to boot
• initrd is an optional initial ramdisk
• CMDLINE is an optional commandline for the new kernel

if no CMDLINE is found or it's length is 0, the default one will be used,

if it starts with a '+' sign the rest of the CMDLINE will be appended to the default one.

otherwise CMDLINE will be used as new command line for the booted kernel.

keep in mind that the TF201 stock kernel require at least this string for boot:

"mem=1022M@2048M mem=1022M@2048M tegra_fbmem=4098560@0xabe01000 gpt"

kernel_chooser support also an optional default entry. the /data/.kernel file.
if this file exist you have 10 seconds to stop the default boot.

WARNING: kernel_chooser don't have an android initrd built in like root_chooser. you have to create a config for boot android too.

if you want to be able to boot android you have to create the related entry in the kernel.d directory.
let's say that you have the android_kernel and android_initrd under the /data/boot directory.
your /data/.kernel.d/android file will be:

android
/dev/mmcblk0p8:/boot/android_kernel:/boot/android_initrd

ok, lets make some example.

if you have your linux distro on your microsd and you have the kernel in /data/boot/zImage you should have a file named /data/.kernel.d/mylinux with this content:

my linux distro from my microSD
/dev/mmcblk0p8:/boot/zImage
+root=/dev/mmcblk1p1 rootwait

if you have your linux distro on an usb stick with the kernel on the /folder directory of the same device, your file /data/.kernel.d/anyname should looks like:

my linux distro from my USB stick
/dev/sda1:/folder/zImage
+root=/dev/sda1 rootwait

explication of some terms:
the "rootwait" kernel parameter tell to the kernel to wait for the specified root device, this is required for booting from USB stick and microsd because they are recognized after the kernel tries to mount the root device.
the "root" kernel parameter tell to the kernel what is the root device. this should point to the device containing your linux distro.

note for ubuntu users: please read carefully the Step 4.

from v3 we support a background image :)
you have to put your background in /data/background.bmp.
it MUST be in bitmap format with size of 1280 x 800 and 24bit of depth.
here you are a screenshot. ( colors are inverted )

Step 4

configure root_chooser

if you have installed your linux distro in the root directory of a device ( usually usb stick or microsd ) you can skip to step 5, except if you use ubuntu, which refuse to start without root_chooser due to some extra-userfriendly-feature. ( thanks to Vanryu )

if you have extracted the tarball into a sub directory of a device or you have an ext4 dd image of a root FS you must use root_chooser as initramfs.

the trick is that kernel_chooser can optionally load an initial ramdisk beside your kernel.

i made root_chooser, which read configuration from the kernel command line.

the syntax is the following:

newroot=blkdev:root_directory_or_image:init_path,init_arg1,init_arg2

where:

• blkdev is the block device where your penguin lives
• root_directory_or_image is the path to the directory where you extracted the tarball or the path to the dd image of a ext4 partition.
• init_path is the path to the init process
• init_arg1,init_arg2,init_arg3... are optional parameters for the init_path program

let's do some example!

i have a gentoo chroot under /data/gentoo, a working kernel in /data/boot/zImage and the root_chooser initrd in /data/boot/root_chooser. my /data/.kernel.d/gentoo will be:

gentoo
/dev/mmcblk0p8:/boot/zImage:/boot/root_chooser
+newroot=/dev/mmcblk0p8:/gentoo:/sbin/init

if i want a rescue entry:

gentoo ( rescue )
/dev/mmcblk0p8:/boot/zImage:/boot/root_chooser
+newroot=/dev/mmcblk0p8:/gentoo:/sbin/init,single

i have an ext4 dd image of a working ubuntu in /data/media/ubuntu.img ( /data/media = /sdacrd on our TF201), the usual kernel in /data/boot/zImage and root_chooser v6 in /data/boot/root_chooser6.gz, my kernel_chooser config file will be:

ubuntu from dd image
/dev/mmcblk0p8:/boot/zImage:/boot/root_chooser
+newroot=/dev/mmcblk0p8:/media/ubuntu.img:/sbin/init

let's say that you have ubuntu on the root of your microSD, you must use root_chooser anyway, due to some ubuntu's extra-userfriendly-features. ( this is a workaround IMHO ).
you'll have:

 ubuntu from SD
/dev/mmcblk0p8:/boot/zImage:/boot/root_chooser
+newroot=/dev/mmcblk1p1:/:/sbin/init

step 5

flash kernel_chooser

WARNING: ensure to have created the android config and files.

first of all you have to choose what method to use for flash the image.

• fastboot - it's an open source program that uses an open source protocol
• nvflash - it's a closed source program that writes partitions using nvidia custom stuff

personally i prefer fastboot since i can look at his source code if i wish, while when you launch nvflash everything is a secret....
download the image :

• fastboot.blob if you choose fastboot
• nvflash.LNX if you choose nvflash

now connect you TF201 to your pc and shut it off. if you choose to use fastboot:

1. take your TF201
2. keep pressed the volume down button
3. press the power button until the tablet vibrates
4. release the volume down key after you see 4 icons
5. press volume down until the green USB icon being selected
6. press volume up
7. go to your pc
8. open a shell and type fastboot -i 0x0b05 flash boot /path/to/fastboot.blob
9. you should see a blue bar on your TF201

if you choose to use nvflash:

1. take your TF201
2. keep pressed the volume up button
3. press the power button until the tablet vibrates
4. release the volume up button after 5 seconds
5. go to your pc
6. open a shell and type wheelie --blob your_secter_blob_file.bin
7. then run nvflash -r --download 6 /path/to/nvflash.LNX

Step 6

reboot

reboot you TFP. we are done! ;)

TODO

notes for chroot into arch linux
tegra video drivers instructions
give a look to opentegra
ubuntu and arch_linux root_patches.

NO VIDEO AVAILABLE FOR v7, can someone make this ?