OpenBMC non-UBI Code Update

Two BMC Code Updates layouts are available:

  • Static, non-UBI layout - The default code update

  • UBI layout - enabled via obmc-ubi-fs machine feature

This document describes the non-UBI, default code update. The UBI code update can be found here: ubi-code-update.md

The host code update can be found here: host-code-update.md

After building OpenBMC, you will end up with a set of image files in tmp/deploy/images/<platform>/. The image-* symlinks correspond to components that can be updated on the BMC:

  • image-bmc → obmc-phosphor-image-<platform>-<timestamp>.static.mtd

    The complete flash image for the BMC

  • image-kernel → fitImage-obmc-phosphor-initramfs-<platform>.bin

    The OpenBMC kernel FIT image (including the kernel, device tree, and initramfs)

  • image-rofs → obmc-phosphor-image-<platform>.squashfs-xz

    The read-only OpenBMC filesystem

  • image-rwfs → rwfs.jffs2

    The read-write filesystem for persistent changes to the OpenBMC filesystem

  • image-u-boot → u-boot.bin

    The OpenBMC bootloader

Additionally, there are two tarballs created that can be deployed and unpacked by REST:

  • <platform>-<timestamp>.all.tar

    The complete BMC flash content: A single file (image-bmc) wrapped in a tar archive.

  • <platform>-<timestamp>.tar

    Partitioned BMC flash content: Multiple files wrapped in a tar archive, one for each of the u-boot, kernel, ro and rw partitions.

Preparing for BMC code Update

The BMC normally runs with the read-write and read-only file systems mounted, which means these images may be read (and written, for the read-write filesystem) at any time. Because the updates are distributed as complete file system images, these filesystems have to be unmounted to replace them with new images. To unmount these file systems all applications must be stopped.

By default, an orderly reboot will stop all applications and unmount the root filesystem, and the images copied into the /run/initramfs directory will be applied at that point before restarting. This also applied to the shutdown and halt commands -- they will write the flash before stopping.

As an alternative, an option can be parsed by the init script in the initramfs to copy the required contents of these filesystems into RAM so the images can be applied while the rest of the application stack is running and progress can be monitored over the network. The update script can then be called to write the images while the system is operational and its progress output monitored.

Update from the OpenBMC shell

To update from the OpenBMC shell, follow the steps in this section.

It is recommended that the BMC be prepared for update (note that the environment variable needs to be set twice for initramfs be able to read it due to the U-Boot redundant environments):

fw_setenv openbmconce copy-files-to-ram copy-base-filesystem-to-ram
fw_setenv openbmconce copy-files-to-ram copy-base-filesystem-to-ram
reboot

Copy one or more of these image-* files to the directory:

/run/initramfs/

(preserving the filename), then run the update script to apply the images:

/run/initramfs/update

then reboot to finish applying:

reboot

During the reboot process, the update script will be invoked after the file systems are unmounted to complete the update process.

Some optional features are available, see the help for more details:

/run/initramfs/update --help

Update via REST

An OpenBMC system can download an update image from a TFTP server, and apply updates, controlled via REST. The general procedure is:

  1. Prepare system for update
  2. Configure update settings
  3. Initiate update
  4. Check flash status
  5. Apply update
  6. Reboot the BMC

Prepare system for update

Perform a POST to invoke the PrepareForUpdate method of the /flash/bmc object:

curl -b cjar -k -H "Content-Type: application/json" -X POST \
    -d '{"data":  []}' \
    https://${bmc}/org/openbmc/control/flash/bmc/action/prepareForUpdate

This will setup the u-boot environment and reboot the BMC. If no other images were pending the BMC should return in about 2 minutes.

Configure update settings

There are a few settings available to control the update process:

  • preserve_network_settings: Preserve network settings, only needed if updating the whole flash
  • restore_application_defaults: update (clear) the read-write file system
  • update_kernel_and_apps: update kernel and initramfs. If the partitioned tarball will be used for update then this option must be set. Otherwise, if the complete tarball will be used then this option must not be set.
  • clear_persistent_files: ignore the persistent file list when resetting applications defaults
  • auto_apply: Attempt to write the images by invoking the Apply method after the images are unpacked.

To configure the update settings, perform a REST PUT to /control/flash/bmc/attr/<setting>. For example:

curl -b cjar -k -H "Content-Type: application/json" -X PUT \
    -d '{"data": 1}' \
    https://${bmc}/org/openbmc/control/flash/bmc/attr/preserve_network_settings

Initiate update

Perform a POST to invoke the updateViaTftp method of the /flash/bmc object:

curl -b cjar -k -H "Content-Type: application/json" -X POST \
    -d '{"data": ["<TFTP server IP address>", "<filename>"]}' \
    https://${bmc}/org/openbmc/control/flash/bmc/action/updateViaTftp

Note the <filename> shall be a tarball.

Check flash status

You can query the progress of the download and image verification with a simple GET request:

curl -b cjar -k https://${bmc}/org/openbmc/control/flash/bmc

Or perform a POST to invoke the GetUpdateProgress method of the /flash/bmc object:

curl -b cjar -k -H "Content-Type: application/json" -X POST \
    -d '{"data": []}' \
    https://${bmc}/org/openbmc/control/flash/bmc/action/GetUpdateProgress

Note:

  • During downloading the tarball, the progress status is Downloading
  • After the tarball is downloaded and verified, the progress status becomes Image ready to apply.

Apply update

If the status is Image ready to apply. then you can either initiate a reboot or call the Apply method to start the process of writing the flash:

curl -b cjar -k -H "Content-Type: application/json" -X POST \
    -d '{"data": []}' \
    https://${bmc}/org/openbmc/control/flash/bmc/action/Apply

Now the image is being flashed, you can check the progress with above step’s command as well.

  • During flashing the image, the status becomes Writing images to flash
  • After it's flashed and verified, the status becomes Apply Complete. Reboot to take effect.

Reboot the BMC

To start using the new images, reboot the BMC using the warmReset method of the BMC control object:

curl -b cjar -k -H "Content-Type: application/json" -X POST \
    -d '{"data": []}' \
    https://${bmc}/org/openbmc/control/bmc0/action/warmReset