This folder contains the major scripts for the “Chrome OS factory shim”. The shim is used for installing a Chrome OS image (kernel, rootfs and firmware) to a device. It's also known as “(factory) install shim”, “RMA shim”, or “Reset shim”.
The factory shim is designed to allow operators removing USB stick once it's booted, so the boot process is slightly different. The shim relies on
initramfs technology to bootstrap and load all contents into memory, then start an upstart service to display the menu.
Inside chroot, do:
build_packages --board $BOARD build_image --board $BOARD factory_install
The output disk image is in
If you have local changes in
src/platform/factory_installer, please remember to do
cros_workon --board $BOARD start factory_installer emerge-$BOARD factory_installer
If you have local changes in
src/platform/initramfs, please remember to do
cros_workon --board $BOARD start chromeos-initramfs
There‘s no need to emerge
chromeos-initramfs because it’s always re-built in
The factory shims were signed in a special way for security reasons. It needs to boot with “developer switch turned on” and “boot in recovery mode”.
If you have a signed factory shim, follow the steps to boot:
Ctrl-Dto request turn on developer switch, and
If you boot factory shim in developer mode (
Ctrl-U), few functions won't work, for example recovering TPM.
Factory shims do not provide shells by default for security reason. If you can still see virtual terminal consoles, try VT0, VT1, VT2, VT3 - there are lots of debug messages there.
If you do need a shell to debug, add
cros_debug to kernel command line. You can do this in
build_image --board $BOARD --boot_args cros_debug factory_install
For an existing image, you can use
make_dev_ssd.sh to change kernel command line easily:
# inside chroot cd ~/trunk/src/platform/vboot_reference/scripts/image_signing ./make_dev_ssd.sh -i $PATH_TO_IMAGE_OR_USB_DEVICE \ --partitions 2 --recovery --edit_config
This will bring an editor to allow editing command line.
make_dev_ssd.sh is also available on all Chrome OS image (even factory shim) - try
If you boot a factory shim with
cros_debug, then you should have one shell in VT2 or VT3. Moreover, if you can enter the menu, ‘S’ will give you the full shell.
frecon-lite) provides text-based console. If you can't see anything on screen, redirect the console to another device, for example Servo consoles so you can check why
frecon failed. To do this, add
console=ttyS0,115200n8 to kernel command line (use the
make_dev_ssd.sh or add
--boot_args as explained in previous section). Some devices may need different TTY name for example
ttyS1. Please check the care-and-feed doc of your device.
If the menu or frecon will die and adding
cros_debug does not help, you probably want to attach serial console (for example SuzyQ) and get everything except factory shim UI (menu) there. To do that:
/usr/sbin/factory_tty.sh and find the
TTY_CONSOLE= line. If it already has valid serial console (for example
ttyS0), move to step 3.
TTY_CONSOLEand build image.
make.conf in board overlay, to find or add one setting (assume serial console is
Then,then re-build the
factory_installer package and factory shim:
emerge-$BOARD factory_installer build_image --board $BOARD factory_install
Mount the rootfs and rename
/etc/init/console-ttyS0.conf to something that does not start as
# First enable RW for rootfs. Assume the USB is in /dev/sdX. cd ~/trunk/src/platform/vboot_reference/scripts/image_signing sudo ./make_dev_ssd.sh -i /dev/sdX --recovery \ --remove_rootfs_verification --partitions 2 # Mount (assume your shim is in /dev/sdX) sudo mount /dev/sdX /media cd /media/etc/init sudo mv console-ttyS0.confg debug-ttyS0.conf cd - # To leave /media folder so we can unmount. sudo umount /media