[chromebook] Use Arch ARM without Dev mode?

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[chromebook] Use Arch ARM without Dev mode?

Postby Kozaki » Sun Jan 03, 2016 10:25 pm

Hi,

Does using Archlinux ARM on a chromebook require Developer mode to be ON forever, i.e. like with Crouton / unlike with SeaBIOS? I searched the 'Platforms' ARMv7 and forum for a while without luck on this.

Presently looking for a Chromebook notebook, possibly ARM out of curiosity, professional, technical and ethical motivations. Might fall for a supported Cb (like the Asus C100 "Flip") to get my hands dirty. Then for the ARMv8 Cortex-A72 model with USB type-C by Mediatek if/when it's available. Seeing it as the closest modern portable device ever to the brain *uck working Psion s5 ultra-light notebook (that's how I used it during my studies).

Have only scratched what going GNU/Linux (and BSD) on ARM means in practical terms. The (u)booting process itself is yet unclear. As I'm a simple Linux user who's been using Arch only on x86 (PII, Duron to IvyBridge) desktops, laptops and small servers.
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Re: [chromebook] Use Arch ARM without Dev mode?

Postby tincman » Thu Jan 21, 2016 7:50 pm

Yes, for all Chromebooks w/o developer mode, the bootloader will only accept images signed with the key stored in the firmware. This is currently a key only Google has access to, and AFAIK, there is no way to add/replace keys w/o reflashing the read-only firmware, which is tricky (but not impossible) to do. However, I think much of the first-stage bootloader is device-dependent, as well as the key storage...

Info on the verified boot process: http://www.chromium.org/chromium-os/chr ... d-recovery
Info on flashing custom r/o firmware: https://docs.google.com/presentation/d/ ... slide=id.p

The SeaBIOS/"Legacy Boot" case was an x86 only situation to deal with UEFI incompatibilities, where google had signed a SeaBIOS binary that booted, but then loaded untrusted/unsigned kernels from there. No such option exists on ARM.

Regarding Chromebooks: I've recently acquired an Acer Chromebook 13, which I very much enjoy (despite not having everything working). I had considered a Samsung Chromebook 2 for a long time, but I've been dealing with annoying mali blobs on my Odroids, and had no interest in trying to get them working w/ a more expensive chromebook as well (aside from the fact they only support GLES and I would need to recompile a chunk of packages and/or run them in software rendering).
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