TPM PCRs are scarce, so systemd allocates PCR-like registers in the TPM's NV memory. The way these NvPCRs are securely anchored was reworked in v262. I wrote up how the new design works by rebuilding an NvPCR from scratch against a software TPM: katexochen.aro.bz/posts/system...
katexochen.aro.bz
Understanding NvPCRs in systemd v262
systemd answers TPM PCR scarcity with additional PCR-like registers allocated in the TPM’s NV memory, with an anchoring design that was reworked in v262. In this hands-on deep dive, we rebuild a syste...
