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# SPDX-License-Identifier: GPL-2.0+
# Copyright (c) 2018 Google, Inc
# Written by Simon Glass <>
# Support for a Chromium OS Google Binary Block, used to record read-only
# information mostly used by firmware.
from collections import OrderedDict
import command
from entry import Entry, EntryArg
import fdt_util
import tools
# Build GBB flags.
# (src/platform/vboot_reference/firmware/include/gbb_header.h)
gbb_flag_properties = {
'dev-screen-short-delay': 0x1,
'load-option-roms': 0x2,
'enable-alternate-os': 0x4,
'force-dev-switch-on': 0x8,
'force-dev-boot-usb': 0x10,
'disable-fw-rollback-check': 0x20,
'enter-triggers-tonorm': 0x40,
'force-dev-boot-legacy': 0x80,
'faft-key-override': 0x100,
'disable-ec-software-sync': 0x200,
'default-dev-boot-legacy': 0x400,
'disable-pd-software-sync': 0x800,
'disable-lid-shutdown': 0x1000,
'force-dev-boot-fastboot-full-cap': 0x2000,
'enable-serial': 0x4000,
'disable-dwmp': 0x8000,
class Entry_gbb(Entry):
"""An entry which contains a Chromium OS Google Binary Block
Properties / Entry arguments:
- hardware-id: Hardware ID to use for this build (a string)
- keydir: Directory containing the public keys to use
- bmpblk: Filename containing images used by recovery
Chromium OS uses a GBB to store various pieces of information, in particular
the root and recovery keys that are used to verify the boot process. Some
more details are here:
but note that the page dates from 2013 so is quite out of date. See
README.chromium for how to obtain the required keys and tools.
def __init__(self, section, etype, node):
Entry.__init__(self, section, etype, node)
self.hardware_id, self.keydir, self.bmpblk = self.GetEntryArgsOrProps(
[EntryArg('hardware-id', str),
EntryArg('keydir', str),
EntryArg('bmpblk', str)])
# Read in the GBB flags from the config
self.gbb_flags = 0
flags_node = node.FindNode('flags')
if flags_node:
for flag, value in gbb_flag_properties.iteritems():
if fdt_util.GetBool(flags_node, flag):
self.gbb_flags |= value
def ObtainContents(self):
gbb = 'gbb.bin'
fname = tools.GetOutputFilename(gbb)
if not self.size:
self.Raise('GBB must have a fixed size')
gbb_size = self.size
bmpfv_size = gbb_size - 0x2180
if bmpfv_size < 0:
self.Raise('GBB is too small (minimum 0x2180 bytes)')
sizes = [0x100, 0x1000, bmpfv_size, 0x1000]
sizes = ['%#x' % size for size in sizes]
keydir = tools.GetInputFilename(self.keydir)
gbb_set_command = [
'gbb_utility', '-s',
'--hwid=%s' % self.hardware_id,
'--rootkey=%s/root_key.vbpubk' % keydir,
'--recoverykey=%s/recovery_key.vbpubk' % keydir,
'--flags=%d' % self.gbb_flags,
'--bmpfv=%s' % tools.GetInputFilename(self.bmpblk),
tools.Run('futility', 'gbb_utility', '-c', ','.join(sizes), fname)
tools.Run('futility', *gbb_set_command)
return True