ubuntu-phone team mailing list archive

[Julia Palandri <julia.palandri@xxxxxxxxxxxxx>]

Hi Torsten,

do you have this published somewhere to link to?

Thanks,

On Tue, Jun 16, 2015 at 10:00 PM, Torsten Sachse <torsten.sachse@xxxxxxxxx>
wrote:

> On Tue, 16 Jun 2015, Oliver Grawert wrote:
>
>> Am Dienstag, den 16.06.2015, 13:35 -0400 schrieb Rodney Dawes:
>>
>>> You may have problems running chroot from within the Terminal app
>>> though, as it seems to be blocked from executing the shell in the chroot
>>> for some reason. It works perfectly fine over phablet-shell though.
>>>
>>
>> to work around this you can:
>>
>> android-gadget-service enable ssh
>> ssh localhost
>> chroot ~/debian-chroot
>>
>
> Some time ago, I wrote a little guide for someone on this list but
> apparently I forgot to send it to the entire list. Feel free to use it
> according to the GPL, if you like. The guide [1] is below. I hope it can
> be of help to people who are not yet perfectly familiar with the system.
> Apologies to those who already know all of the below and to Oliver, to
> whom I accidentally sent this twice.
>
> Torsten
>
> [1]:
> This is a simple guide describing how to set up a chroot on a Ubuntu
> touch device. It also explains how to set it up so that the chroot is
> located on the SD-card to save internal storage space and goes into some
> detail about why simply installing the chroot on an SD-card is not
> possible.
>
> The guide is structured as follows:
> 1) Comments on file systems and permissions
> 2) Using phone only
> 3) Using computer and phone (recommended)
> 4) Unsing an image file (recommended)
>
> 1) Comments on file systems and permissions
> Only some file system types support file permissions in a way the chroot
> needs them. An SD-card likely uses FAT32 which does not support any type
> of permissions and, hence, the chroot can't run on it.  The permissions
> reported by commands like "ls -l" do not have any significance on such
> file systems. Some Android handsets for instance support EXT3 or ECT4 on
> their SD-cards making installing a chroot a lot easier.
>
> 2) Using phone only (not recommended since it breaks over the air updates)
> It is possible to install debootstrap on the phone by remounting the
> system as read-write and executing the following commands. At least it
> worked on my BQ on r22. Imagine you want to install your chroot into the
> directory "jessie" which should reside in the current working directory:
>
> sudo mount / -o remount,rw
> sudo apt-get update
> sudo apt-get install debootstrap
> sudo debootstrap --arch=armhf jessie ./jessie
> http://http.debian.net/debian
>
> This only works on the internal storage without what's explained in
> section 4).
>
> 3) Using computer and phone
> The problem with this debootstrap-command failing your average computer
> is that your computer cannot execute binaries compiled for the ARM
> architechture. This is why you have to add the option --foreign to
> debootstrap which tells it to only download all packages and leave
> anything that needs executing of any of the installed binaries to
> another system. So do (sudo might not be needed):
>
> sudo debootstrap --arch=armhf --foreign jessie ./jessie
> http://http.debian.net/debian
>
> If you were to install an i386 architechture on a x86_64 system, you
> would not have to specify the --foreign flag as both should be able to
> run on an ordinary 64-bit processor although they're different
> architechrures.
>
> Now best create a tar archive from this which you then copy to your
> phone. It does not matter whether the archive is put on the SD-card or
> the internal storage. The second command is needed to turn on ssh
> support, which is reset upon every reboot.
>
> tar -cvzf jessie.tar.gz jessie
> sudo service ssh start
> scp jessie.tar.gz phablet@ubuntu-phablet:DIRECTORY_OF_YOUR_CHOICE
>
> Now you only have to extract the archive wherever you want the new
> directory "jessie" to reside. Without what's expained in section 4),
> this will only work on your internal storage.  Then, you only have to go
> into your chroot and finish the installation process. So do on the phone
> (the first command is needed since the terminal app is somehow
> restricted to execute binaries):
>
> ssh localhost
> tar -xvzf jessie.tar.gz
> sudo chroot jessie /bin/bash
> /debootstrap/debootstrap --second-stage
> exit
>
> Now, you should be able to chroot into your new system using the third
> of the above commands.
>
> 4) Using an image file
> First, create an image file on the system on which you execute the first
> debootstrap command. To create an 1GB image, do
>
> dd if=/dev/zero of=IMAGE.img bs=1G count=1
>
> Note that the B in GB is left out. "if" stands for "input file", "of"
> for "output file" and "bs" for "block size". There are more efficient
> commands out there, but those only work on certain types of file
> systems, AFAIK. This one also works on an SD-card or a tempfs. Please
> note the use of /dev/zero and not /dev/random or /dev/urandom as that
> would take a lot longer and make it take a lot longer to transfer the
> image between devices.
>
> Mount the image file to a loop-device and create a file system on it.
> Without a file system, you cannot yet mount the image to a directory,
> only to a block-device. So do
>
> sudo losetup -f
>
> and remember the output. Replace every "LOOP" in the following commands
> by the output of the above command. First, assign the image to a block
> device:
>
> sudo losetup LOOP IMAGE.img
>
> Next, create the file system on it:
>
> sudo mkfs -t ext4 LOOP
>
> Next, detach the image from the loop device:
>
> sudo losetup -d LOOP
>
> If you get command not found errors, just install the missing
> programmes. Now, create the directory and mount the image file to it:
>
> mkdir jessie
> sudo mount -o loop IMAGE.img $(pwd)/jessie
>
> The command "pwd" will make sure you give mount an absolute path to your
> current working directory. Now, use the directory "jessie" with
> debootstrap as explained above (the command including the --foreign
> flag). After you're finished, umount the image via
>
> sudo umount $(pwd)/jessie
>
> and create an archive of the image file (will compress all the zeroes in
> the archive to almost nothing) and transfer that to your phone. Both
> SD-card and internal storage are fine. On your phone, create the
> directory "jessie" somewhere on the internal storage, mount the image to
> it and perform the second stage.
>
> You should now have a nice chroot on your phone that does not waste
> internal storage space.
>
>
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-- 

Julia