Firmware
Contents
Custom Firmware
The stock/factory firmware on some Chromebooks and Chromeboxes contains a legacy boot payload (RW_LEGACY) capable of running Linux out of the box; however, many ChromeOS devices, particularly those with BayTrail/Braswell CPUs, do not include this capability stock and must use a 3rd party firmware update in order to run GalliumOS (or any other OS).
Three types of custom firmware updates are available (though not all types are available for every device):
Types
- RW_LEGACY
- Updates/replaces the stock legacy boot payload (SeaBIOS) included on many models; supplements the ChromeOS / secure boot payload (BOOT_STUB)
- Leaves all stock functionality intact, including the developer mode boot (white "OS verification is OFF") screen
- Allows device to dual-boot GalliumOS alongside ChromeOS
- Does not require disabling the firmware write-protect
- Carries zero risk of bricking the device
- On some models, includes bugfixes and enables additional functionality
- BOOT_STUB
- Replaces the ChromeOS verified boot payload with a legacy boot payload (SeaBIOS)
- Removes the developer mode boot (white "OS verification is OFF") screen
- Requires the firmware write-protect screw to be removed
- Removes the ability to run ChromeOS, creating a small risk of bricking your device
- Leaves the recovery mode (ESC + REFRESH + POWER) functionality of the stock ROM intact
- If you engage this key sequence, device will reboot and try to run ChromeOS Recovery (which will fail)
- This process will repeat on every boot until you disassemble the device and briefly disconnect the battery
- Full Firmware / ROM
- A complete firmware image which replaces the hardware init component (coreboot) and payload components (BOOT_STUB, RW_LEGACY) of the stock firmware with updated and/or customized versions of coreboot and SeaBIOS
- Removes the developer mode boot (white "OS verification is OFF") screen
- Removes the ability to run ChromeOS, creating a small risk of bricking your device
- Offers the best support for booting all OSes besides ChromeOS (including Windows).
- On many models, adds full hardware support for virtualization (vmx / VT-x)
- Fixes many bugs and/or idiosyncrasies associated with the stock firmware (but could potentially add new ones)
- Essentially turns your ChromeOS device into a "regular" PC / laptop
Availability Options
Check Hardware Compatibility and the appropriate Support page to determine the status of your model.
There are several custom firmware options available, depending on your Chromebook/box model class, and the features you require:
| Firmware Provider / Link | ARM | Pineview | Sandy/Ivy Bridge | Haswell | Broadwell | Bay Trail | Braswell | notes |
|---|---|---|---|---|---|---|---|---|
| CoolStar | No | No | No | Full Firmware (Chromebooks) | Full Firmware (Chromebooks) | No | No | • Fixes factory firmware bugs • Boots Linux, Mac OS X, and Windows! • Install Guide: Haswell, Broadwell • Firmware build scripts |
| johnlewis.ie | No | No | Full Firmware, BOOT_STUB (all) | Full Firmware, BOOT_STUB, RW_LEGACY (all) | RW_LEGACY (all) | BOOT_STUB (all) | No | • Fixes factory firmware bugs • General purpose firmware for Linux • Single script works for all supported models • Firmware build scripts/configs not published |
| MattDevo (MrChromebox) |
No | No | Full Firmware (Chromeboxes) | Full Firmware (Chromeboxes), RW_LEGACY (all) | Full Firmware (Chromeboxes), RW_LEGACY (all) | RW_LEGACY (all) | No | • Fixes factory firmware bugs • Headless boot support for servers • PXE booting support • Supports integration of Kodi Media Center • Firmware source/build scripts and payload source |
Additions and corrections, please let us know: contact@galliumos.org
Firmware and NVRAM Flags
crossystem
GBB Flags
TODO: Add detail on GBB flags, relationship to crossystem flags, note flat battery issues and WP restrictions.
