Arch Linux

zoickx

Member

Registered: 2018-07-13

Posts: 1

[SOLVED] Chromebook partitioning

Hey everyone,

I have already asked pretty much the same question some time ago here on reddit, but that did not yield much result.
Basically, the question goes like this:

    (TLDR)
    My chromebook's SSD has 12 partitions, only one of which I understand the purpose of. Is wiping them all going to seriously break my device?

    [ANSWER]
    No, it is completely fine to wipe the entire disk (mmcblk0) and partition it however you please. I did not touch the boot drives and was completely fine booting from a USB stick. A full arch installation with GRUB worked like a charm.
    Even more than that, I was able to restore the device to factory defaults (that is, it installed ChromeOS with all updates automatically)
    by simply turning off Developer mode and using an official ChromeOS recovery image (which is a cleaner way than using an old dd image)
    (Once again, I did not touch boot drives, so I am not sure if it would be possible if those were wiped too)
   

Now a bit of explanation. I've got an Acer Chromebook 14 with a custom bootloader already flashed. It is currently running ChromeOS alongside Ubuntu 18.04, which I installed using chrx.
There are 3 drives: mmcblk0, mmcblk0boot0, mmcblk0boot1. Partitions on the first one (fdisk -l):

Device             Start      End  Sectors  Size Type
/dev/mmcblk0p1   8671232 12771327  4100096    2G Microsoft basic data 
/dev/mmcblk0p2     20480    53247    32768   16M ChromeOS kernel 
/dev/mmcblk0p3   4476928  8671231  4194304    2G ChromeOS root fs 
/dev/mmcblk0p4     53248    86015    32768   16M ChromeOS kernel 
/dev/mmcblk0p5    282624  4476927  4194304    2G ChromeOS root fs 
/dev/mmcblk0p6  12771328 12804095    32768   16M ChromeOS kernel 
/dev/mmcblk0p7  12804096 61038591 48234496   23G ChromeOS root fs 
/dev/mmcblk0p8     86016   118783    32768   16M Microsoft basic data 
/dev/mmcblk0p9     16450    16450        1  512B ChromeOS reserved 
/dev/mmcblk0p10    16451    16451        1  512B ChromeOS reserved 
/dev/mmcblk0p11       64    16447    16384    8M unknown 
/dev/mmcblk0p12   249856   282623    32768   16M EFI System

p7 (the biggest one) contains Ubuntu root and p12 is the ESP. Others I cannot easily mount or do not clearly understand the purpose of.

I am thinking of replacing ChromeOS with Arch altogether.
I would like to remove all the partitions on mmcblk0 and replace them with just 2 for / and the ESP,  however, not understanding how chromebooks work, I am scared to change anything by hand.
Installation, Partitioning, Chromebook or device pages on the Wiki do not seem to give any clear information on the matter.

Additionally, if it turns out to be fine to remove all the ChromeOS stuff, is there a humane way of resetting the laptop back to factory defaults?

Thanks!

P.S. Sorry if this is not the right place for the post. I do realise that the question is not strictly Arch-related, but for many other systems manual partitioning during installation is not a problem, their GUI installers "just work" on chromebooks.

Last edited by zoickx (2018-10-03 17:22:51)

flortsch

Member

From: Linz, Austria

Registered: 2015-07-21

Posts: 39

Website

Re: [SOLVED] Chromebook partitioning

After reading this disk-format specification I think that you can fully wipe the mmcblk0 disk.
The partitions you are mentioning all seem to be only ChromeOS specific.

In order to fully backup and restore your disk, you could use dd, as described by this wiki page.