Samsung ARM Chromebook: stuck in nv-u-boot and trying to recover to chromeos.

[mohit raju]

Hi, 

Current status, These are the only operations that I am able to perform on it.

1. When i boot my chromebook, it goes to SMDK5250# prompt. 

2. If I boot with a usb drive containing a Linux image it boots into linux.

Now I am guessing that the SMDK5250 prompt is from the nv-u-boot that I installed on the system. Now I am trying to recover the chromeos back.

When I boot by putting in a recovery image in the usb drive, this is what happens. I created the image using google's online utility tool.

1. Again the SMDK5250# prompt shows up.

2. Then I run vboot_twostop.

3. This goes into a screen showing options to enter 

      a. developer mode 

      b. enter normal mode. 

      When i press keys to enter any of these modes it fails and returns to the prompt.

4. Then when i run vboot_twostop again, it enters into the recovery mode and shows the message "Yuck" and complains that the image is not for the correct device or is not signed.

So, what changes do i need to make in order for the device to accept a image as signed.

Or is there any other approach here ?

Thanks

[Mike Frysinger]

did you disable write protect on your flash and update u-boot that way ?

-mike

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[Sonny Rao]

On Wed, Sep 17, 2014 at 4:44 AM, mohit raju <mohi...@gmail.com> wrote:

So, I'm guessing you've either flashed your own firmware onto the SPI
flash (you disabled write protect) or you're using a chained nv_uboot loaded
from emmc by the stock firmware.

In the former case, I think you can try just booting the recovery
stick like a normal USB stick, which you mentioned works, and it
should at least begin recovery, though I'm not sure if it will succeed
without the TPM being in the correct state. You can look at the logs
on the vt2 and vt3 while it's recoverign or mount the 1st partition of
the recovery stick and look for the logs there afterward.

In the latter case, you should boot the original firmware into
recovery mode by using escape-refresh-power and then inserting the
recovery stick and it should "just-work".

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[mohit raju]

1. I did not flash my own firmware, i am not even remotely intelligent enough to write my own firmware.

2. I am using a chained nv_uboot loaded from emmc, as i have to write nv_boot-snow.kpart to first partition of the linux installations that i make on the usb stick. I use this tutorial to create these usb sticks http://archlinuxarm.org/platforms/armv7/samsung/samsung-chromebook#qt-platform_tabs-ui-tabs2. I am able to boot my chr

omebbok into linux using usb sticks created with the help of this tutorial.

3. Now usb sticks using only the above tutorial are working. As in these sticks boot and I can start installin

g archlinux oto the disk. The recovery stick that I prepare usig recovery chromebook utility is detected BUT c

hromebook complains that it is incorrect image or is not signed.

4. ESC+refresh+power mode reboots the machine and takes me to SMDK5250# prompt.

5. Also, my /dev/mmcblk0p13 is empty. EMPTY.

> email to chromium-os-discuss+unsub...@chromium.org.

[Sonny Rao]

On Wed, Sep 17, 2014 at 12:32 PM, mohit raju <mohi...@gmail.com> wrote:
> 1. I did not flash my own firmware, i am not even remotely intelligent
> enough to write my own firmware.
> 2. I am using a chained nv_uboot loaded from emmc, as i have to write
> nv_boot-snow.kpart to first partition of the linux installations that i make
> on the usb stick. I use this tutorial to create these usb sticks
> http://archlinuxarm.org/platforms/armv7/samsung/samsung-chromebook#qt-platform_tabs-ui-tabs2.
> I am able to boot my chr
> omebbok into linux using usb sticks created with the help of this tutorial.
> 3. Now usb sticks using only the above tutorial are working. As in these
> sticks boot and I can start installin
> g archlinux oto the disk. The recovery stick that I prepare usig recovery
> chromebook utility is detected BUT c
> hromebook complains that it is incorrect image or is not signed.
> 4. ESC+refresh+power mode reboots the machine and takes me to SMDK5250#
> prompt.

This doesn't sound correct to me. Escape-refresh-power should bring
you to a recovery screen saying "ChromeOS is missing or damaged"
if you still have the stock firmware on SPI flash.

>> > email to chromium-os-dis...@chromium.org.

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[mohit raju]

Hi, 

I did do this

flashrom -p linux_spi:dev=/dev/spidev1.0 -w nv_image-snow.bin

So, yes i think it had a custom firmware on it (correct me if I am wrong).  

Is it possible to go back to legacy uboot now? If yes. where can i get the legacy uboot img, as it is possible to flash rom onto SPI from the bootable linux usb stick.

[mohit raju]

Hi,

Also, it says the following when it tries to run the recovery image.

invalid key block signature. 

verifying key block signature failed

Thanks

[Sonny Rao]

On Wed, Sep 17, 2014 at 3:58 PM, mohit raju <mohi...@gmail.com> wrote:
>> Hi,
>
>
> I did do this
>
> flashrom -p linux_spi:dev=/dev/spidev1.0 -w nv_image-snow.bin
>
> So, yes i think it had a custom firmware on it (correct me if I am wrong).

Yes sounds like it

> Is it possible to go back to legacy uboot now? If yes. where can i get the
> legacy uboot img, as it is possible to flash rom onto SPI from the bootable
> linux usb stick.

There should be a .bin with the original firmware somewhere on the
recovery image, but I'd have to look to see where. You'll also lose
your HWID (hardware id) which means you wont get auto updates unless
you restore that.

[mohit raju]

Hi, 

Thanks, I have been trying to find the original firmware blob from past few hours, if you have the same model of chromebook(xe303c12-a01us), could you help me out by reading it out from your chromebook. 

Thanks. This has been really helpfull.

[Mike Frysinger]

see this thread: https://groups.google.com/a/chromium.org/d/msg/chromium-os-discuss/vHkPtmRJECU/3618p0yrN3YJ

-mike

--

[mohit raju]

Hi, I did as the thread that you linked to specifies, now I have the following files generated, when i ran the chromeos-firmware with the --sb_extract flag. These are the files what were generated.

root@rajumoh-lptp:/tmp# ls -lat

total 199172

drwxrwxrwt 22 root    root         4096 syys  18 23:01 .

-rwxr-xr-x  1 root    root        13849 syys  18 23:01 crosutil.sh

-rwxr-xr-x  1 root    root       446884 syys  18 23:01 dump_fmap

-rwxr-xr-x  1 root    root       737612 syys  18 23:01 flashrom

-rwxr-xr-x  1 root    root       430552 syys  18 23:01 crossystem

-rwxr-xr-x  1 root    root        24202 syys  18 23:01 updater4.sh

-rw-r--r--  1 root    root          883 syys  18 23:01 VERSION.md5

-rwxr-xr-x  1 root    root       703496 syys  18 23:01 mosys

-rw-r--r--  1 root    root         2190 syys  18 23:01 VERSION

-rwxr-xr-x  1 root    root       664256 syys  18 23:01 gbb_utility

-rw-------  1 root    root      4194304 syys  18 23:01 bios.bin

-rw-r--r--  1 root    root        31150 syys  18 23:01 shflags

-rwxr-xr-x  1 root    root         5335 syys  18 23:01 common.sh

-rw-r--r--  1 root    root           75 syys  18 23:01 VERSION.signer

-rwxr-xr-x  1 root    root       418476 syys  18 23:01 vpd

-rwxr-xr-x  1 root    root         4341 syys  18 23:01 crosfw.sh

-rw-------  1 root    root      4194304 syys  18 23:01 bios-snow-2695.132.ro.bin

-rw-r--r--  1 root    root         4883 syys  18 23:01 updater_custom.sh

-rw-------  1 root    root      4194304 syys  18 23:01 bios-snow-2695.132.rw.bin

-rw-r--r--  1 root    root       131072 syys  18 23:01 ec.bin

-rw-r--r--  1 root    root       131072 syys  18 23:01 ec-2695.132.bin

-rw-------  1 root    root      4194304 syys  18 23:01 bios_rw.bin

So, as a confirmation is bios-snow-2695.132.rw.bin the bin that I need to flash my SPI with 

OR is it both bios-snow-2695.132.rw.bin and bios-snow-2695.132.ro.bin that i need to flash ?

Also, you comment says "but the bios.bin in there is the full flash image and won't include the factory data" towards the end. Is it of concern in my case or had it to do with coreboot in that particular(HP chromebook) case only ?

Thanks

[mohit raju]

Hi all,

Thanks for all the help. I flashed the SPI with the bios-snow-2695.132.rw.bin. read write bin would do as the ro part always reads the rw part first. If a new update is found is writes that partition onto itself.

After the flash, the system booted into recovery and asked to enter the recovery usb. Then the recovery went ahead with not problems.

Typing from the restored chromebook.

Thanks and again :-D