EDKII open source has OPAL driver at
SecurityPkg\Tcg\Opal. It includes a feature named
BlockSid, which is defined in TCG Physical Presence and TCG OPAL BlockSid specification. The TCG PP spec defines PP opcode to enable/disable
BlockSid, which may need user confirmation. However, current EDKII OPAL driver just uses a normal variable
(OPAL_EXTRA_INFO_VAR_NAME/gOpalExtraInfoVariableGuid) to store the BlockSid enable/disable. This driver does not follow TCG recommendation to use PP process to request user confirmation on BlockSid state change. Also this variable is NOT locked. It means any one can overwrite this variable and bypass BlockSid operation.