225 lines
8.8 KiB
Markdown
225 lines
8.8 KiB
Markdown
---
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title: ASUS Chromebook C201 installation guide
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x-toc-enable: true
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...
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**Libreboot 20160907 only. This board was dropped in subsequent releases, but
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may be added again in the future.**
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**This documentation is retained from Libreboot 20160907, but it may also be
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prudent to check documentation from Libreboot 20160907 itself. It is included
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in the source code archive, for that release.**
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The version of Depthcharge used here is very old, from 2016, and support for
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this laptop was dropped in recent releases. It will be re-added at a later
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date. If you wish to use Libreboot on this board, right now you must install
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Libreboot 20160907. This page has been retained on libreboot.srht.site for now, but
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you should refer to the documentation provided in the Libreboot 20160907
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release if you want to learn more. NOTE: in that release, the documentation is
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written in raw HTML, because the Markdown-based static site generator used on
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libreboot.srht.site had not yet been written at that point.
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These instructions are for installing Libreboot to the ASUS Chromebook
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C201 (more known under a name [*veyron speedy*](../misc/codenames.md)).
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Since the device ships with Coreboot, the installation
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instructions are the same before and after flashing Libreboot for the
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first time.
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Look at the [list of ROM images](#rom) to see which image is compatible
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with your device.
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Libreboot can be installed internally from the device, with sufficient
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privileges. The installation process requires using *Google's modified
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version of flashrom*, that has support for reflashing the Chromebook's
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SPI flash. Otherwise, flashing externally will work with the upstream
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flashrom version.
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*Google's modified version of flashrom* is free software and its
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source code is made available by Google:
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[flashrom](https://chromium.googlesource.com/chromiumos/third_party/flashrom/).\
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It is not distributed along with Libreboot yet. However, it is
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preinstalled on the device, with ChromeOS.
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Installing Libreboot internally requires sufficient privileges on the system
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installed on the device. When the device has ChromeOS installed (as it does
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initially), it is necessary to gain root privileges in ChromeOS, to be able to
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access a root shell.
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Gaining root privileges on ChromeOS
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--------------------------------
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In order to gain root privileges on ChromeOS, developer mode has to be
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enabled from the recovery mode screen and debugging features have to be
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enabled in ChromeOS.
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Instructions to access the [recovery mode
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screen](../depthcharge/#recovery_mode_screen) and [enabling developer
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mode](../depthcharge/#enabling_developer_mode) are available on the page
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dedicated to [depthcharge](../depthcharge/).
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Once developer mode is enabled, the device will boot to the [developer
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mode screen](../depthcharge/#developer_mode_screen). ChromeOS can be
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booted by waiting for 30 seconds (the delay is shortened in Libreboot)
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or by pressing *Ctrl + D*
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After the system has booted, root access can be enabled by clicking on
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the *Enable debugging features* link. A confirmation dialog will ask
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whether to proceed.\
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After confirming by clicking *Proceed*, the device will reboot and ask
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for the root password to set. Finally, the operation has to be confirmed
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by clicking *Enable*.
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After setting the root password, it becomes possible to log-in as root.
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A tty prompt can be obtained by pressing *Ctrl + Alt + Next*. The
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*Next* key is the one on the top left of the keyboard.
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Preparing the device for the installation
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Before installing Libreboot on the device, both its software and
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hardware has to be prepared to allow the installation procedure and to
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ensure that security features don't get in the way.
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Configuring verified boot parameters
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------------------------------------
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It is recommended to have access to the [developer mode
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screen](../depthcharge/#developer_mode_screen) and to [configure the
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following verified boot
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parameters](../depthcharge/#configuring_verified_boot_parameters):
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- Kernels signature verification: *disabled*
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- External media boot: *enabled*
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Those changes can be reverted later, when the device is known to be in a
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working state.
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Removing the write protect screw
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--------------------------------
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Since part of the SPI flash is write-protected by a screw, it is
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necessary to remove the screw to remove the write protection and allow
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writing Libreboot to the *read-only* part of the flash.
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To access the screw, the device has to be opened. There are 8 screws to
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remove from the bottom of the device, as shown on the picture below. Two
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are hidden under the top pads. After removing the screws, the keyboard
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plastic part can be carefully detached from the rest. *Beware: there
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are cables attached to it!* It is advised to flip the keyboard plastic
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part over, as shown on the picture below. The write protect screw is
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located next to the SPI flash chip, circled in red in the picture below.
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It has to be removed.
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[](https://libreboot.srht.site/img/c201/screws.jpg) [](https://libreboot.srht.site/img/c201/wp-screw.jpg)
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The write protect screw can be put back in place later, when the device
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is known to be in a working state.
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Installing Libreboot to the SPI flash
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=====================================
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The SPI flash (that holds Libreboot) is divided into various partitions
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that are used to implement parts of the CrOS security system. Libreboot
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is installed in the *read-only* coreboot partition, that becomes
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writable after removing the write-protect screw.
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Installing Libreboot internally, from the device
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------------------------------------------------
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Before installing Libreboot to the SPI flash internally, the device has
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to be reassembled.
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All the files from the `veyron_speedy` release (or build) have to be
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transferred to the device.
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The following operations have to be executed with root privileges on the
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device (e.g. using the `root` account). In addition, the
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`cros-flash-replace` script has to be made executable:
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chmod a+x cros-flash-replace
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The SPI flash has to be read first:
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flashrom -p host -r flash.img
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*Note: it might be a good idea to copy the produced flash.img file at
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this point and store it outside of the device for backup purposes.*
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Then, the `cros-flash-replace` script has to be executed as such:
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sudo bash ./cros-flash-replace flash.img coreboot ro-frid
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If any error is shown, it is definitely a bad idea to go further than
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this point.
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The resulting flash image can then be flashed back:
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flashrom -p host -w flash.img
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You should also see within the output the following:
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Verifying flash... VERIFIED.
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Shut down. The device will now boot to Libreboot.
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Installing Libreboot externally, with a SPI flash programmer
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------------------------------------------------------------
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Before installing Libreboot to the SPI flash internally, the device has
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to be opened.
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The SPI flash is located next to the write protect screw. Its layout is
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indicated in the picture below. Note that it is not necessary to connect
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`WP#` since after removing the screw it is pulled up weakly to 3v3. Before
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writing to the chip externally, the battery has to be unplugged.
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Battery connector is located under the heat spreader, that has to be
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unscrewed from the rest of the case. It is located on
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the right and has colorful cables, as shown on the picture below.
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[](https://libreboot.srht.site/img/c201/spi-flash-layout.jpg)
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[](https://libreboot.srht.site/img/c201/battery-connector.jpg)
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All the files from the `veyron_speedy` release (or build) have to be
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transferred to the host.
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The following operations have to be executed with root privileges on the
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host (e.g. using the `root` account). In addition, the
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`cros-flash-replace` script has to be made executable:
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chmod a+x cros-flash-replace
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The SPI flash has to be read first (using the right spi programmer):
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flashrom -p *programmer* -r flash.img
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*Note: it might be a good idea to copy the produced flash.img file at
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this point and store it outside of the device for backup purposes.*
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Then, the `cros-flash-replace` script has to be executed as such:
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./cros-flash-replace flash.img coreboot ro-frid
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If any error is shown, it is definitely a bad idea to go further than
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this point.
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The resulting flash image can then be flashed back (using the right spi
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programmer):
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flashrom -p *programmer* -w flash.img
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You should also see within the output the following:
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Verifying flash... VERIFIED.
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The device will now boot to Libreboot.
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Installing Debian
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---------------------
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Debian is recommended for this device (which is on that list.
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See <https://wiki.debian.org/InstallingDebianOn/Asus/C201>.
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Also look at the HCL entry for operating systems (Debian, Devuan, Parabola):
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<https://libreboot.srht.site/docs/hardware/c201.md>
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