OpenBMC & Host Code Update

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 → flash-<platform>-<timestamp>

    The whole-of-flash image for the BMC

  • image-initramfs → core-image-minimal-initramfs-palmetto.cpio.lzma.u-boot

    The small initramfs image; used for early init and flash management

  • image-kernel → cuImage

    The OpenBMC kernel cuImage (combined kernel and device tree)

  • image-rofs → obmc-phosphor-image-palmetto.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

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, the 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:

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. 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": ["<TFTP server IP address>", "<filename>"]}' \
    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_only: update kernel and initramfs
  • 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

Check flash status

You can query the progress of the download and image verificaton 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: the status will not advance from Writing images to flash without calling the GetUpdateProgress method.

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.

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

Host code update

The host firmware (or "BIOS") can be updated in a similar method. Because the BMC does not use the host firmware it is updated when the download is completed. This assumes the host is not accessing its firmware.

Perform a POST request to call the updateViaTftp method of /control/flash/bios (instead of /control/flash/bmc used above). To initiate the update:

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

And to check the flash status:

curl -b cjar -k https://bmc/org/openbmc/control/flash/bios