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[Libreboot] Porting Libreboot to the C201 Chromebook (veyron_speedy)

From: Paul Kocialkowski
Subject: [Libreboot] Porting Libreboot to the C201 Chromebook (veyron_speedy)
Date: Mon, 03 Aug 2015 11:21:36 +0200

Over the past week or so, I've been working to get Libreboot running on
the latest ARM Chromebook: the C201, manufactured by Asus (codename
veyron_speedy). The laptop is running with a RK3288 SoC and ships with
Google's version of Coreboot preinstalled. It should require no
proprietary code nor any proprietary firmware load or microcode update
to boot, thus it would be a good fit for Libreboot, as a fully free
distribution of Coreboot.

In addition to that, the device's embedded controller (that handles
aspects of power management as well as the keyboard and a few other
things) is a microcontroller that is also running free software: the
free embedded controller firmware from Google.

Aside from that, it has a soldered Wi-Fi/bluetooth BCM4354 chip (cannot
be removed) that has a free driver but requires to load a proprietary
firmware on the chip. However, it is easy to work around that issue and
not use that chip at all, e.g. using an ath9k_htc dongle on one of the
two USB ports.

The GPU is a Mali T764, on which Luc has been doing some early work to
have free software support for it. It is uncertain[0] how long it will
take to have an usable free replacement for it, but now that there is
that hardware available, free graphics for Mali T GPUs would mean having
a recent laptop running fully free software, down to the firmware level,
without losing any major hardware feature, something that has hardly
ever been achieved yet. Thus, I believe it is of the utmost importance
to back Luc up on this, even if big players like ARM are trying hard to
make Lima not happen and to make it difficult for Luc to keep going.

Another aspect that I still have to look at in-depth is the ability to
use hardware video encoding/decoding. The RK3288 has an auxiliary
processor for that task, but it is unclear whether it can be used with
free software or not, though the first indications that I've gathered
are positive.

At this point, I've been able to boot up Debian on the device, and the
xfce4 interface is quite usable. It even runs big programs like
Iceweasel/Firefox and LibreOffice without inconveniences.

However, it cannot run desktop environments that depend on GL
acceleration, such as gnome-shell, which is a shame since those would be
a good fit for it. The CPU is simply too slow for offering a decent
experience with software rendering (llvmpipe).

Overall, I truly hope this device creates an incentive to free the last
remaining parts that can only work with proprietary software to this
day. Its potential would be huge, especially since it's a good fit for
travellers. With the security model inherited from Chromium OS, this
would be one of the safest laptops to be used by journalists or
activists. If Tails was to be ported to it, it would become easy to have
a secure and anonymous setup.

I have successfully fixed and compiled Coreboot and all the necessary
bits and pieces for the C201, so I'll be spending the next few days
sending patches, discussing how to integrate it to Libreboot and getting
the actual work done.

I also plan on documenting all my findings (especially things like how
to access UART, how to remove the SPI flash's write protect, how to
reflash it externally, etc) on my coding blog, for now.



Paul Kocialkowski, Replicant developer

Replicant is a fully free Android distribution running on several
devices, a free software mobile operating system putting the emphasis on
freedom and privacy/security.


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