TPM Policy Record (Type 8) Rules
Record Types 8 is used by legacy Intel® TXT FIT boot only and is not needed, if latter is not used.
- There can be zero or one TPM Policy Record in the FIT.
- Each Type 8 entry is at an address that is accessible by the processor at reset vector.
- The address field contains the TPM_POLICY_PTR structure. This structure contains the address, where the TPM Policy information resided.
- The version field is set to 0, if TPM_POLICY_PTR describes an Indexed IO type pointer. The version field is set to 1, if TPM_POLICY_PTR describes a flat memory pointer.
- If indexed IO type pointer is used, the Address field holds a structure of the type INDEX_IO_ADDRESS. This structure contains the IO addresses of the index and data register, access width and position of the bit that holds the TPM policy.
- If flat memory type pointer is used, the Address field holds a 64-bit memory address. The memory address should be within the low 4 GB of address space. Bit 0 at this address holds the TPM Policy.
- The TPM policy says whether TPM should be enabled or disabled. If TPM Policy = 0, the TPM should be disabled. If TPM Policy is 1, the TPM should be enabled.
- The default setting is 1. In other words, if this structure is not present or is invalid, the Startup ACM will behave as if TPM Policy = 1.
- The C_V bit in this entry should be clear to 0.
- The Size field is not used. BIOS should set this field to 0.