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

Update from the OpenBMC shell

To update from the OpenBMC shell, copy one or more of these image-* files to the directory:

/run/initramfs/

(preserving the filename), then reboot. Before the system reboots, the new image will be copied to the appropriate flash partition.

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. Configure update settings
  2. Initiate update
  3. Check flash status

Configure update settings

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

  • preserve_network_settings: Preserve network settings, only needed if updating uboot
  • restore_application_defaults: update read-only file system
  • update_kernel_and_apps_only: update kernel and initramfs
  • clear_persistent_files: Erase persistent files

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 flash with a simple GET request:

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

Host code update

Using a similar method, we can update the host firmware (or "BIOS"), by performing 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