diff --git a/docs/TPM2_PCR_MEASUREMENTS.md b/docs/TPM2_PCR_MEASUREMENTS.md index 7601c15531..462a86b36c 100644 --- a/docs/TPM2_PCR_MEASUREMENTS.md +++ b/docs/TPM2_PCR_MEASUREMENTS.md @@ -29,6 +29,16 @@ Currently, four components will issue TPM2 PCR measurements: A userspace measurement event log in a format close to TCG CEL-JSON is maintained in `/run/log/systemd/tpm2-measure.log`. +## Measurements Added in Future + +We expect that we'll add further PCR extensions in future (both in firmware and +user mode), which also will be documented here. When executed from firmware +mode future additions are expected to be recorded as `EV_EVENT_TAG` +measurements in the event log, in order to make them robustly +recognizable. Measurements currently recorded as `EV_IPL` will continue to be +recorded as `EV_IPL`, for compatibility reasons. However, `EV_IPL` will not be +used for new, additional measurements. + ## PCR Measurements Made by `systemd-boot` (UEFI) ### PCS 5, `EV_EVENT_TAG`, "loader.conf"