On 3/30/20 3:28 PM, Jarkko Sakkinen wrote:

On Mon, Mar 30, 2020 at 11:15:34AM -0400, Stefan Berger wrote:

quoted

From: Stefan Berger <stefanb@linux.ibm.com>

Recent extensions of the TPM2 ACPI table added 3 more fields
including 12 bytes of start method specific parameters and Log Area
Minimum Length (u32) and Log Area Start Address (u64). So, we extend
the existing structure with these fields to allow non-UEFI systems
to access the TPM2's log.

The specification that has the new fields is the following:
   TCG ACPI Specification
   Family "1.2" and "2.0"
   Version 1.2, Revision 8

Adapt all existing table size calculations to use
offsetof(struct acpi_table_tpm2, start_method_specific)
[where start_method_specific is a newly added field]
rather than sizeof(struct acpi_table_tpm2) so that the addition
of the new fields does not affect current systems that may not
have them.

Cc: linux-acpi@vger.kernel.org

quoted

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

You have this comment:

/* Platform-specific data follows */

You mean there 'was this comment'? I actually removed this comment 
because I didn't know what it meant or what it has to do with 'platform':

-
-       /* Platform-specific data follows */
+       u8  start_method_specific[12];
+       u32 log_area_minimum_length;
+       u64 log_area_start_address;

Specs: 
https://trustedcomputinggroup.org/wp-content/uploads/TCG_ACPIGeneralSpecification_v1.20_r8.pdf

PDF Page 16 / Doc page 10 bottom.

start_method_specific is obviously related to the start_method field. 
The subsequent two fields are optional and show those 2 filelds we know 
from the TCPA ACPI table.

Can you elaborate a bit which platform you are speaking of? It is now
enabled for everything.

/Jarkko