RMA stands for Return Merchandise Authorization. When there’s a problem that the end user cannot solve, the user returns the device to the partner’s service center for diagnosis and repair. The service center may swap components and reinstall the firmware and/or software image. For Chromebooks, that means the service center may need to disable write protection and change the HWID to match the new configuration.
Chromebooks are highly secured. With verified boot and write protection, it’s difficult for the service center to run diagnosis and repair programs (usually built and customized by partners) because those won’t be signed by Google. Service centers may also have limited (or even no) network access. In general, what the partner needs is a tool that fulfills these requirements:
The RMA shim image is designed to meet these requirements. An RMA shim image is a combination of existing Chrome OS factory bundle components, all combined into one disk, including:
A problem for regular (single-board) RMA shims is that we have to create separate per-board RMA shims for each project, which makes it hard to manage shim images and physical USB drives. A universal shim contains multiple RMA shims for different boards, which is easier to manage and distribute.
Pros:
Cons:
image_tool is a useful tool to manage RMA shims. We can get this tool by downloading the factory public repo.
$ git clone https://chromium.googlesource.com/chromiumos/platform/factory $ cd factory/
The tool is located at setup/image_tool. It's recommended to sync the git repo periodically to get the latest version.
(in factory/ repository) $ git pull
After downloading the factory repo, we can run the unit test for RMA commands to check if it runs normally on the machine. The tool should be able to run in a fresh Linux environment without chroot.
$ py/tools/image_tool_rma_unittest.py
To create an RMA shim, you should first get a factory bundle and follow the steps below.
RMA test list is different from the test list used in factory manufacture line. For instance, there is no factory server during RMA. Hence, we need another test list for RMA.
The recommended way is to create a test list that inherits generic_rma.test_list.json, which already takes care of general RMA settings such as disabling factory server and enabling rma_mode, and then add factory tests to RMAFFT group.
{ "inherit": [ "generic_rma.test_list" ], "label": "RMA Test List for <project>", "definitions": { "RMAFFT": { "subtests": [ ... ... ] } } }
constants.phase is set to PVT).After getting all the bundle components ready, we can combine these components into a single RMA shim image. To create an RMA shim image from a factory bundle, use image_tool rma create command:
$ setup/image_tool rma create \
--board BOARD \
--factory_shim path/to/factory_install_shim.bin \
--test_image path/to/chromiumos_test_image.bin \
--toolkit path/to/install_factory_toolkit.run \
--release_image path/to/chromiumos_image.bin \
--hwid path/to/hwid_bundle.sh \
--output rma_image.bin
The command can be simplified if all the components are put in their respective bundle directories (release_image/, test_image/, etc.):
$ setup/image_tool rma create \
--board BOARD \
--output rma_image.bin
We can also specify the active test list when creating the RMA shim, so that we don't need to modify active_test_list.json in factory toolkit.
$ setup/image_tool rma create \
--board BOARD \
--output rma_image.bin \
--active_test_list rma_main
Flash the rma_image.bin to a USB drive, boot it with developer switch enabled in recovery mode (see following steps), and then the device will boot from the RMA shim.
Note: The following instructions only work for a Google signed RMA shim. If you are using a developer signed RMA shim, the boot process is the same as booting from a test image.
Use dd command to flash a shim image to a USB drive or SD card, replacing /dev/sdX with the name of the USB/SD device.
$ sudo dd if=rma_image.bin of=/dev/sdX bs=8M iflag=fullblock oflag=dsync
If you have a Chromium OS development environment, you can also use cros flash command in chroot.
$ cros flash usb:// rma_image.bin
ESC + F3(REFRESH) + POWER to enter recovery mode.CTRL + D to turn on developer switch.ENTER to confirm.ESC + F3(REFRESH) + POWER to enter recovery mode again (no need to wait for wiping).rma_image.bin.POWER + VOL_UP + VOL_DOWN for at least 10 seconds, and release them to enter recovery mode.VOL_UP + VOL_DOWN to show recovery menu.VOL_UP or VOL_DOWN to move the cursor to “Confirm Disabling OS Verification”, and press POWER to select it.POWER + VOL_UP + VOL_DOWN for at least 10 seconds, and release them to enter recovery mode again (no need to wait for wiping).rma_image.bin.The RMA shim has a menu that allows the user to select an action to perform, which is described in Factory Installer README. Moreover, if the RMA shim is created using image_tool rma create command, the tool adds a flag RMA_AUTORUN=1 in lsb-factory file, which sets the default action of the menu depending on the cr50 version and hardware write protect status, such that:
You can stop the default action and return to shim menu by pressing any key within 3 seconds when the console prompts “press any key to show menu instead”.
During installation, you can remove the RMA shim when the copy is complete (the text color changes from yellow to green). After the installation, the device will boot into the test image with factory toolkit. Run through the factory tests to complete the flow. The last test should wipe out the factory test image and enable the release image.
We can use image_tool rma merge command to create a universal shim using multiple RMA shims.
$ setup/image_tool rma merge \
-i soraka.bin scarlet.bin \
-o universal.bin
To delete a previously generated output image, specify the -f option:
$ setup/image_tool rma merge \
-i soraka.bin scarlet.bin \
-o universal.bin -f
image_tool rma merge supports merging universal shims. If there are duplicate boards, it will ask the user to select which one to use. It can be used to update a board in a universal shim using an updated single-board RMA shim.
$ setup/image_tool rma merge \
-i universal.bin soraka_new.bin \
-o universal_new.bin
Scanning 2 input image files...
Board soraka has more than one entry.
========================================================================
(1)
From universal.bin
board : soraka
install_shim : 10323.39.28
release_image : 10575.37.0 (Official Build) dev-channel soraka
test_image : 10323.39.24 (Official Build) dev-channel soraka test
toolkit : soraka Factory Toolkit 10323.39.24
firmware : Google_Soraka.10431.32.0;Google_Soraka.10431.48.0
hwid : None
complete : None
toolkit_config: None
lsb_factory : lsb_factory
========================================================================
(2)
From soraka_new.bin
board : soraka
install_shim : 10323.39.31
release_image : 10575.37.0 (Official Build) dev-channel soraka
test_image : 10323.39.24 (Official Build) dev-channel soraka test
toolkit : soraka Factory Toolkit 10323.39.24
firmware : Google_Soraka.10431.32.0;Google_Soraka.10431.48.0
hwid : None
complete : None
toolkit_config: None
lsb_factory : lsb_factory
========================================================================
Please select an option [1-2]:
Using a universal RMA shim is exactly the same as using a normal single-board RMA shim. Flash the image to a USB drive and boot from it using the instructions mentioned above.
There are other image_tool commands that makes verifying and modifying RMA shims easier. For detailed description and usage, please use the --help argument of the commands. For instance:
$ setup/image_tool rma show --help
image_tool rma show command can print the component versions in an RMA shim.
$ setup/image_tool rma show -i soraka.bin This RMA shim contains boards: soraka ======================================================================== board : soraka install_shim : 10323.39.31 release_image : 10575.37.0 (Official Build) dev-channel soraka test_image : 10323.39.24 (Official Build) dev-channel soraka test toolkit : soraka Factory Toolkit 10323.39.24 firmware : Google_Soraka.10431.32.0;Google_Soraka.10431.48.0 hwid : None complete : None toolkit_config: cb5b52296cd4fcb0418b6879c0acc32b lsb_factory : d2c9d6a7d32ee3b1279c2b0b27244727 ========================================================================
This command also applies to universal RMA shim.
$ setup/image_tool rma show -i universal.bin This RMA shim contains boards: soraka scarlet ======================================================================== board : soraka install_shim : 10323.39.31 release_image : 10575.37.0 (Official Build) dev-channel soraka test_image : 10323.39.24 (Official Build) dev-channel soraka test toolkit : soraka Factory Toolkit 10323.39.24 firmware : Google_Soraka.10431.32.0;Google_Soraka.10431.48.0 hwid : None complete : None toolkit_config: cb5b52296cd4fcb0418b6879c0acc32b lsb_factory : d2c9d6a7d32ee3b1279c2b0b27244727 ======================================================================== board : scarlet install_shim : 10211.68.0 release_image : 10575.67.0 (Official Build) stable-channel scarlet test_image : 10211.53.0 (Official Build) dev-channel scarlet test toolkit : scarlet Factory Toolkit 10211.53.0 firmware : Google_Scarlet.10388.26.0 hwid : None complete : None toolkit_config: None lsb_factory : c82d4c1f831bf20d7cdc70138fe4ef72 ========================================================================
image_tool rma replace command can replace components in an RMA shim. For instance, to replace the HWID bundle in an RMA shim with a new one:
$ setup/image_tool rma replace -i rma_image.bin --hwid new_hwid_bundle.sh
If the RMA shim is a universal shim, argument --board is needed.
$ setup/image_tool rma replace -i universal.bin \
--board soraka --hwid new_hwid_bundle.sh
This command supports replacing release_image, test_image, toolkit, factory_shim, firmware, hwid, complete_script and toolkit_config.
image_tool rma extract command can extract a single-board RMA shim from a universal shim.
$ setup/image_tool rma extract -i universal.bin -o extract.bin Scanning input image file... Please select a board to extract. ======================================================================== (1) board : soraka install_shim : 10323.39.31 release_image : 10575.37.0 (Official Build) dev-channel soraka test_image : 10323.39.24 (Official Build) dev-channel soraka test toolkit : soraka Factory Toolkit 10323.39.24 firmware : Google_Soraka.10431.32.0;Google_Soraka.10431.48.0 hwid : None complete : None toolkit_config: cb5b52296cd4fcb0418b6879c0acc32b lsb_factory : d2c9d6a7d32ee3b1279c2b0b27244727 ======================================================================== (2) board : scarlet install_shim : 10211.68.0 release_image : 10575.67.0 (Official Build) stable-channel scarlet test_image : 10211.53.0 (Official Build) dev-channel scarlet test toolkit : scarlet Factory Toolkit 10211.53.0 firmware : Google_Scarlet.10388.26.0 hwid : None complete : None toolkit_config: None lsb_factory : c82d4c1f831bf20d7cdc70138fe4ef72 ======================================================================== Please select an option [1-2]:
image_tool edit_lsb command can modify lsb-factory config, such as RMA_AUTORUN flag.
$ setup/image_tool edit_lsb -i rma_image.bin Current LSB config: ======================================================================== CHROMEOS_AUSERVER=http://... CHROMEOS_DEVSERVER=http://... FACTORY_INSTALL=1 HTTP_SERVER_OVERRIDE=true FACTORY_INSTALL_FROM_USB=1 RMA_AUTORUN=true ======================================================================== (1) Modify Chrome OS Factory Server address. (2) Modify cutoff config in cros payload (only for old devices). (3) Enable/disable complete prompt in RMA shim. (4) Enable/disable autorun in RMA shim. (q) Quit without saving changes. (w) Apply changes and exit. Please select an option [1-4, q, w]:
or
$ setup/image_tool edit_lsb -i universal.bin --board soraka
Note:
lsb-factory file. The actual config is stored in cros payload, so the modifications in the file will be overwritten.lsb-factory. Using this command to modify cutoff config is only effective for factory shim older than this version. For factory shim later than this version, please use image_tool edit_toolkit_config command to edit cutoff config.image_tool edit_toolkit_config command can modify toolkit config, such as active test list and cutoff config (after version 12162.0.0).
$ setup/image_tool edit_toolkit_config -i rma_image.bin
Toolkit config:
========================================================================
{
"cutoff": {
"CUTOFF_BATTERY_MAX_PERCENTAGE": 90,
"CUTOFF_BATTERY_MIN_PERCENTAGE": 60,
"CUTOFF_METHOD": "battery_cutoff",
"CUTOFF_AC_STATE": "remove_ac"
},
"active_test_list": {
"id": "main_rma"
}
}
========================================================================
(1) Modify active test list.
(2) Modify test list constants.
(3) Modify cutoff config.
(q) Quit without saving changes.
(w) Apply changes and exit.
Please select an option [1-3, q, w]:
or
$ setup/image_tool edit_toolkit_config -i universal.bin --board soraka
image_tool payload toolkit command can unpack and repack the factory toolkit in an RMA shim.
$ setup/image_tool payload toolkit -i rma_image.bin --unpack toolkit_path (Edit some files in toolkit_path/ ...) $ setup/image_tool payload toolkit -i rma_image.bin --repack toolkit_path
or
$ setup/image_tool payload toolkit \
-i universal.bin --board soraka --unpack toolkit_path
(Edit some files in toolkit_path/ ...)
$ setup/image_tool payload toolkit \
-i universal.bin --board soraka --repack toolkit_path