% tpm2_pcrreset(1) tpm2-tools | General Commands Manual
tpm2_pcrreset(1) - Reset one or more PCR banks
tpm2_pcrreset [OPTIONS] PCR_INDEX ...
tpm2_pcrreset(1) - Reset PCR value in all banks for specified index. More than one PCR index can be specified.
The reset value is manufacturer-dependent and is either sequence of 00 or FF on the length of the hash algorithm for each supported bank.
PCR_INDEX is a space separated list of PCR indexes to be reset when issuing the command.
This tool accepts no tool specific options.
Reset a single PCR
Reset multiple PCRs
tpm2_pcrreset 16 23
On operating system's locality (generally locality 0), only PCR 23 can be reset. PCR-16 can also be reset on this locality, depending on TPM manufacturers which could define this PCR as resettable.
PCR 0 to 15 are not resettable (being part of SRTM). PCR 16 to 22 are mostly reserved for DRTM or dedicated to specific localities and might not be resettable depending on current TPM locality.