Enabling updates on a USB install of chromiumos / chrome osflex

Skip to first unread message

CqN on ChromiumOS v96

Aug 2, 2022, 6:24:03 PMAug 2
to ChromiumOS Discussion

Assume one can set up a usb install with same size partitions as in a hard disk install. USB has plenty of space, say 64MB. Is there a flag, or a boot up settings that can be added or modified so that one can check for and update to a new version from within the running USB chrome osflex?

I am guessing originally, the common usb sticks were very small, and the second set of boot areas, KERN-B, ROOT-B partitions were made minimal to save some space.

Would this not be a very useful feature if we can update a usb, without having to rebuild a new version and redo all the customizations?


Aug 3, 2022, 10:26:30 AMAug 3
to ChromiumOS Discussion, CqN on ChromiumOS v96

I think the new strategy is to do away with the need for USB recovery entirely.
The help page for using the Chromebook Recovery Utility, linked below, now includes language as the first option to use the internet:
I think this is currently only working on newer devices but it could eventually be available on all devices with a change to the disk layout that incorporates the MiniOS.


CqN on ChromiumOS v96

Aug 3, 2022, 3:30:43 PMAug 3
to ChromiumOS Discussion, DennisLfromGA, CqN on ChromiumOS v96
DennyL, Thanks for providing some entirely new to me info.

However, let me emphasize my use case above is not recovery.  Instead, using the usb based (so called live boot in linux parlance)  system instead of the internally installed one.  Do you know if there is any options as I mentioned above available in the current versions to enable such a functionality?

Harry Cutts

Aug 4, 2022, 11:14:24 AMAug 4
to ChromiumOS Discussion, CqN on ChromiumOSFlex, DennisLfromGA
I haven't tried it, but I suspect that you could achieve this by "installing" ChromeOS Flex onto one USB drive from another. Here's what I'm thinking:
  1. Disconnect the internal hard drive from the computer, so that it has no storage devices connected.
  2. Plug in your USB drive with Flex on it (let's call it drive A), and another (large) blank USB drive (drive B). Boot into drive A, then run the ChromeOS Flex installer.
I'm guessing this will result in Flex being installed on drive B with full size KERN-B, ROOT-B, etc., so it should be able to install updates in-place. As I say, though, I haven't done this, so try it at your own risk :-)


Aug 4, 2022, 12:42:17 PMAug 4
to ChromiumOS Discussion, hcu...@chromium.org, CqN on ChromiumOSFlex, DennisLfromGA

It may be possible but I don't know how feasible to use the A/B update method on the Flex live USB.
Partitions kern-B & root-B seem to be unused, also kern-C & root-C for that matter.
That may be what you were alluding to in your first comment.

chronos@localhost ~ $ sudo cgpt show /dev/sda
       start        size    part  contents
           0           1          PMBR (Boot GUID: D6E15EE5-B5C1-8F47-BA72-B44D0EE31152)
           1           1          Pri GPT header
           2          32          Pri GPT table
     5152768    26329055       1  Label: "STATE"
                                  Type: Linux data
                                  UUID: 1959D7C2-3522-2B4D-BBCC-02917125BD00
          69       32768       2  Label: "KERN-A"
                                  Type: ChromeOS kernel
                                  UUID: 44AE4720-4944-F443-9BC4-68B11F490BE7
                                  Attr: priority=1 tries=0 successful=1
      237568     4915200       3  Label: "ROOT-A"
                                  Type: ChromeOS rootfs
                                  UUID: 6D2E104F-1040-5740-A131-BB20C5646CD0
       32837       32768       4  Label: "KERN-B"
                                  Type: ChromeOS kernel
                                  UUID: 94B5B803-ACA8-6B49-97C1-61C90D97ADC2
                                  Attr: priority=0 tries=0 successful=0
      233472        4096       5  Label: "ROOT-B"
                                  Type: ChromeOS rootfs
                                  UUID: 9391952C-9030-364F-8AE0-26DE882C037A
          65           1       6  Label: "KERN-C"
                                  Type: ChromeOS kernel
                                  UUID: 6CB67EA2-B9F1-224B-A406-99C52954B1BE
                                  Attr: priority=0 tries=0 successful=0
          66           1       7  Label: "ROOT-C"
                                  Type: ChromeOS rootfs
                                  UUID: C7643033-32C3-D642-B928-B2C0528C6885


Ted Brandston

Aug 4, 2022, 2:53:36 PMAug 4
to hcu...@chromium.org, ChromiumOS Discussion, CqN on ChromiumOSFlex, DennisLfromGA
I was about to jump in and say "that won't work, it'll filter out removable storage" but looking at the code I think Harry has it right. 

If there's only removable storage to install to, the installer will choose that.

Chromium OS Discussion mailing list: chromium-...@chromium.org
View archives, change email options, or unsubscribe:
To unsubscribe from this group and stop receiving emails from it, send an email to chromium-os-dis...@chromium.org.

CqN on ChromiumOSFlex

Aug 7, 2022, 8:27:00 PMAug 7
to ChromiumOS Discussion, tbran...@google.com, ChromiumOS Discussion, CqN on ChromiumOSFlex, DennisLfromGA, hcu...@chromium.org
After a reading many posts on this in many different discussion groups, this is what I learned.  If you install to a usb flash disk (micro sd card thru apapters etc), the updater for gettting a new version will not work.  The updater is hard coded to detect the usb disks and exit.  This has been most likely the case for a very long time, perhaps from the very beginning of the chromebooks, and continues to be true with the current cromeosflex.

However, THIS WILL WORK.  If you install to an external ssd drive, then the resulting installation will run updater and get the next version when available just like the internal installation behaviour.  I haver tested this to be true on one ssd drive.  However my ssd drive, brand new inexpensive 264GB (Amazon Choice type),  while bootable, was very unreliable and crashed after relatively short periods of running.  When running from usb micro sdcards of name brands I rarely have seen a crash after very long  time (months, years).

Then I learned the ssd drives have different types of semiconductor, some less expensive drives use single storage cell position to indicate not just 2 values (a bit as in the original designs) but 3 or even 4 values.  These are less reliable, though have higher capacities and lower price / GB.  When storing data such as images, audios and videos, if there are errors when using, it will go undetected.  But an an OS may crash on a single bit error!   The majority of use of these disks are for data storage and not for bootable os.

Now  I would like to locate a reliable, bootable, external usb SSD drive, where the memory uses only one bit per cell.  Almost all the internally used SSD drives in laptops, I would expect to be this type, otherwise they would not be able to run any os.

Any suggestions, or opinions?

Reply all
Reply to author
0 new messages