[Libreboot] Parabola on C201

[Albin]

Hi all,

I've now managed to install and boot Parabola from microSD on the c201,
but only (thus far) with the ChromeOS kernel that I extracted from the
internal storage.

I simply followed the Arch instructions here:
http://archlinuxarm.org/platforms/armv7/rockchip/asus-chromebook-flip-c100p

and then Parabola's migration instructions here[0]:
https://wiki.parabola.nu/Migration_from_Arch_Linux_ARM#Install_Parabola_keyring_and_mirror_list

...down to (and excluding) "Bootloader configuration".

I have since tried to find a way to boot without Google's kernel, but
unsuccessfully. I learned a bit about the problem though:

First I was surprised that normal installation images didn't work (I
tried Debian 8) since I had actually disabled signature verification.
After some research[1] however I learned that, despite this, the kernel
(or its substitute, see below) needs to be configured in a particular
way to be loaded. Then reading the following got me excited.

"The ChromeOS firmware doesn't actually look at the kernel, it just
looks for a ChromeOS-specific header that describes it. So if your
custom kernel isn't actually a Linux kernel, but is a custom build of
U-Boot that was packaged as though it was a Chromium OS kernel, the
firmware will happily load it into RAM and jump to it. What happens next
is up to you."[1]

So I figured that if I could get hold of one of these U-Boot images, I'd
be able to dd it into the existing ChromeOS kernel partition on my SD
card and then load linux-libre from there. The chromium project does
provide instructions[2] and even images for this, but for an earlier
version, "snow" instead of "veyron". I tried both the nv_uboot-snow and
nv_uboot-snow-simplefb images but they didn't work as I had hoped.
Pressing Ctrl+U at the libreboot screen now gave me a silent black
screen (and to get out I had to hold the power button to shut down).
That was different from when I tried to boot normal installation images
though, which always just result in a loud *beep*.

Now, maybe this U-Boot method didn't work for other reasons. For
example, my existing partition table doesn't contain /boot formatted
with ext2 or FAT (as required by das U-Boot, apparently) but only kernel
and root (the later with ext4). Still, the instructions[2] said that I
should be able to open a U-Boot prompt by pressing and holding space and
this didn't work.

This is how far I got. I will continue to look for a solution but maybe
someone else has an idea on what to try next.


Thank you for your attention!

Albin


[0] Although I had to use different URLs for keyrings and mirror list.

[1]
https://www.chromium.org/chromium-os/developer-information-for-chrome-os-devices/custom-firmware

[2]
https://www.chromium.org/chromium-os/u-boot-porting-guide/using-nv-u-boot-on-the-samsung-arm-chromebook

Den 2015-12-06 kl. 23:42, skrev Albin:
> 
> 
> Den 2015-12-06 kl. 23:26, skrev Albin:
>> Hi,
>>
>> Den 2015-12-06 kl. 12:46, skrev Paul Kocialkowski:
>>> Hi,
>>>
>>> Le dimanche 06 décembre 2015 à 12:44 +0100, Albin a écrit :
>>>> Den 2015-12-06 kl. 10:33, skrev Paul Kocialkowski:
>>>>> Le samedi 05 décembre 2015 à 15:25 +0100, Albin a écrit :
>>>>>> Den 2015-12-05 kl. 13:27, skrev Paul Kocialkowski:
>>>>>>> Le samedi 05 décembre 2015 à 00:34 +0100, Albin a écrit :
>>>>>>>> I just found another guide
>>>>>>>> (https://gist.github.com/jcs/4bf59314d604538a5098) that mentions a step
>>>>>>>> that's missing on libreboot.org: besides removing the write-protect
>>>>>>>> screw one also has to run "flashrom --wp-disable". This should explain
>>>>>>>> the permissions issue I had.
>>>>>>>
>>>>>>> Can you confirm that this is the case (and that you were already using
>>>>>>> the root account for your first report)? I didn't have to go through
>>>>>>> this step when flashing, but maybe it is required the first time.
>>>>>>
>>>>>> Yes, I was using the root account for the first report. Now I've also
>>>>>> tried to run the command "flashrom --wp-disable" which does output
>>>>>> "SUCCESS". That did NOT help though because, just as before, the command
>>>>>> "./cros-flash-replace flash.img coreboot ro-frid" results in: "bash:
>>>>>> ./cros-flash-replace: Permission denied".
>>>>>
>>>>> Ahh I see, so "Permission denied" is not in all caps (which would have
>>>>> looked like a flashrom error message). I bet this is shell complaining
>>>>> because the script isn't executable. Try running:
>>>>> chmod a+x cros-flash-replace
>>>>>
>>>>> before running it an everything should work fine. Maybe it would be
>>>>> worth mentioning on the installation page.
>>>>>
>>>>
>>>> I had already checked and tried to modify the permissions before asking
>>>> on the email list. I get "Permission denied" despite executable
>>>> permissions (that were already there), even with chmod 777. Isn't that
>>>> strange?
>>>
>>> Maybe your filesystem doesn't allow execution (mounted with noexec?).
>>> Perhaps try moving the files to the internal storage of the device
>>> (instead of an external media that the system might mount with noexec),
>>> or the opposite.
>>>
>>
>> Problem solved; libreboot installed!
>>
>> I first inserted the SD card into a different computer and tried to run
>> the script there but got the same error message. Then I copied over
>> flash.img into the veyron_speedy directory that was created after the
>> compilation process and ran the script from there as user. This worked
>> fine and then I had no trouble installing libreboot on the chromebook
>> using flashrom.
>>
>> It would be good to mention in the documentation that there can be a
>> problem with execution rights. I had the same problem when trying to run
>> the scrip both from the SD card and from the internal storage, i.e.
>> after copying over the files from the SD card.
> 
> I saw that you've added the following to the documentation:
> "the cros-flash-replace script has to be made executable: # chmod a+x
> cros-flash-replace. This did *not* help in my case (so maybe not for
> others also) so I think it should say something else. By the way, the
> circle around the write-protect screw on the image is white, not red as
> said in the docs.
> 
>>
>> Now I only need to figure out how to install a functional GNU system and
>> get rid of ChromeOS. Inserting a Debian installer (armhf) and pressing
>> Ctrl+U results in a loud *beep* even with all the security features
>> disabled. Do I need to prepare a custom installer image?
>>
>> Thanks!
>>
>> Albin
>>
>>>>>>>> Den 2015-12-04 kl. 23:49, skrev Albin:
>>>>>>>>> Hi.
>>>>>>>>>
>>>>>>>>> Tonight I tried to install libreboot onto an ASOS C201. I ran into a
>>>>>>>>> number of difficulties that I managed to overcome (see the points 
>>>>>>>>> below,
>>>>>>>>> my contribution to the docs), but then I got stuck at the point where
>>>>>>>>> one is to run the cros-flash-replace script. The terminal keeps
>>>>>>>>> returning PERMISSION DENIED. The file permissions, however, are the 
>>>>>>>>> same
>>>>>>>>> as just after compilation and I've also removed The Screw as 
>>>>>>>>> instructed.
>>>>>>>>>
>>>>>>>>> Does anyone have a clue what might be the problem?
>>>>>>>>>
>>>>>>>>> Cheers,
>>>>>>>>>
>>>>>>>>> Albin
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Errors found in the documentation:
>>>>>>>>>
>>>>>>>>> 1. There are *eight* screws that need to be removed to open the 
>>>>>>>>> device,
>>>>>>>>> not seven. There is (at least on my device) one also beneath the top
>>>>>>>>> left pad.
>>>>>>>>>
>>>>>>>>> 2. You get into the TTY promt by pressing *Ctrl+Alt+Next*.
>>>>>>>>> *Ctrl+Alt+Previous* is for exiting the promt.
>>>>>>>>>
>>>>>>>>> 3. The guide mentions first "cros-flash-replace" and then
>>>>>>>>> "cros-firmware-replace":
>>>>>>>>>
>>>>>>>>> "Then, the cros-flash-replace script has to be executed as such:
>>>>>>>>> # ./cros-firmware-replace flash.img coreboot ro-frid"
>>>>>>>>>
>>>>>>>>> By the way, shouldn't there be .img extensions after coreboot and 
>>>>>>>>> ro-frid?
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>

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