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Re: [Libreboot] Bricked my c201

From: Albin
Subject: Re: [Libreboot] Bricked my c201
Date: Tue, 16 Feb 2016 16:55:55 +0100
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Hi Paul,

Den 2016-02-16 kl. 16:31, skrev Paul Kocialkowski:
> Hi,
> sorry for the late answer,

No worries!

> Le mardi 19 janvier 2016 à 14:41 +0100, Albin a écrit :
>>> Either way, it's hard to find out exactly why it's refusing to boot
>>> externally, provided that Libreboot still shows the warning about
>>> external media booting being enabled. Still, it is probably either about
>>> the kernel you extracted not being in the right format or the partitions
>>> not being set up correctly.
>>> Perhaps you could send me the kernel file you extracted (I'm not sure I
>>> have a backup of mine) and I could prepare a known-to-work disk image
>>> for you to boot from.
>> That would be very nice but unfortunately I cannot access the files on
>> the USB drive where I saved it. When I insert it into my other (X86_64)
>> computer it shows up as an "unknown" device. Besides, external media
>> booting has now been switched off as well so I really need to reflash
>> the firmware.
> What I can do is prepare a "recovery" SPI flash image with external media boot
> explicitly enabled and signature verification disabled, as well as a disk 
> image
> to dd into an sdcard/usb drive that contains a basic debian rootfs with the
> cros-specific tools (that I will soon integrate in Libreboot).

That would be awesome! As I said above I don't think that I can send you
my ChromeOS kernel as I'm unable to access the file system on the USB
drive where I saved it. Would you still be able to pull it off?

> I'll probably write up a blog post with instructions while I'm at it. 
> Hopefully,
> I'll find time to do this in the next week. Feel free to remind me soon ;)
>>> If that fails, it might mean that you'll have to relfash the SPI flash
>>> with an image that allows running unsigned kernels, which will give us
>>> more flexibility.
>>> Either way, your device is not lost and I'm confident there will always
>>> be a way to straighten it out. If you feel like you don't want to pull
>>> this off yourself, we could see about you sending me the device so that
>>> I do what's needed to fix it.
>> Thank you for the encouragement! I do have an SPI programmer and some
>> experience with flashing externally (T60 and macbook2,1) so I would like
>> to try to unbrick the c201 myself. Still, I could need some help with
>> how to connect the wires to the BBB. I'm familiar with most of the
>> abbreviations but I don't know how to connect HOLD#, CLK and CS#. Maybe
>> you, or somebody else, could expand the documentation with details about
>> BBB wiring, like it's in the other guides.
> That's very generic SPI flashing stuff, so I don't think it belongs in the 
> C201
> guide in particular. CS# and CLK are signals to connect to the matching ends 
> on
> the BB while HOLD# and WP# have to be pulled-up (you can connect them directly
> to VCC if you don't care about potential excessive current flowing).

I don't understand what you mean about pulling up. I guess that write
protect isn't necessary since taking out the Screw should be enough, but
if HOLD# needs to be connected, then I don't know how.

>> Another thing that would be useful, I think, is a libreboot
>> configuration for veyron_speedy with some of the security features
>> switched off. That would give somebody who needs to recover their device
>> another option than reinstalling the backed up factory image.
> That would be doable by changing some GBB bits, so perhaps we could consider
> that. I was more thinking of a quick and dirty code-commenting approach, but 
> if
> this can be done cleanly without changing the code too much, why not
> Perhaps recovery instructions could be part of the C201 install guide then.
> Thanks for your feedback!

Thank you!

> Cheers,


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