Passing Ratchet Status to Guest OSes

Ratchet fuse burning status is passed to guest OS via the kernel device tree. There are separate nodes for MB1, MTS, and MB1-BCT at the following location under the /proc interface.

/proc/device-tree/chosen/ratchet-status

Each node has two fields: status and error.

  • "error" has the appropriate ratchet error value.
  • "status" can have following status strings:
Ratcheting Status Description
not_tried Default status. Ratchet check path is skipped.
skipped_a Active Boot Chain firmware ratchet matches with HW fuses.
skipped_b Inactive Boot Chain firmware ratchet matches with HW fuses.
updated Ratchet fuses are successfully updated with SW ratchet value.
failed Ratchet fuse update(burning) failed.
no_option Ratchet update check skipped as Opt-in fuse is not set by OEM