This document is related to the trusted application examples documentation TA basics.
Standard TA properties must be defined through property flag in macro TA_FLAGS by user_ta_header_defines.h.
"gpd.ta.singleInstance" is a boolean property of the TA.
This property defines if one instance of the TA must be created and will receive all open session request, or if a new specific TA instance must be created for each incoming open session request.
OP-TEE TA flag TA_FLAG_SINGLE_INSTANCE sets to configuration of this property.
The boolean property is set to true if TA_FLAGS sets bit TA_FLAG_SINGLE_INSTANCE, otherwise the boolean property is set to false.
"gpd.ta.multiSession" is a boolean property of the TA.
This property defines if the TA instance can handle several sessions. If disabled, TA instance support only one session. In such case, if the TA already has a opened session, any open session request will return with a busy error status.
This property is meaningless if TA is NOT SingleInstance.
OP-TEE TA flag TA_FLAG_MULTI_SESSION sets to configuration of this property.
The boolean property is set to true if TA_FLAGS sets bit TA_FLAG_MULTI_SESSION, otherwise the boolean property is set to false.
"gpd.ta.instanceKeepAlive" is a boolean property of the TA.
This property defines if the TA instance created must be destroyed or not when all sessions opened towards the TA are closed. If the property is enabled, TA instance, once created (at 1st open session request), is never removed unless the TEE itself is restarted (boot/reboot).
This property is meaningless if TA is NOT SingleInstance.
OP-TEE TA flag TA_FLAG_INSTANCE_KEEP_ALIVE sets to configuration of this property.
The boolean property is set to true if TA_FLAGS sets bit TA_FLAG_INSTANCE_KEEP_ALIVE, otherwise the boolean property is set to false.
"gpd.ta.dataSize" is a 32bit integer property of the TA.
This property defines the size in bytes of the TA allocation pool, in which TEE_Malloc() and friends allocate memory.
The value of the property must be defined by the macro TA_DATA_SIZE from user_ta_header_defines.h.
"gpd.ta.stackSize" is a 32bit integer property of the TA.
This property defines the size in bytes of the stack used for TA execution.
The value of the property must be defined by the macro TA_STACK_SIZE from user_ta_header_defines.h.
TA_FLAG_USER_MODE is a bit flag supported by TA_FLAGS.
This property flag is currently meaningless in OP-TEE. It may be set or not without impact on TA execution. All OP-TEE TAs are executed in user mode/level.
Because of this we do not recommend to use this flag.
TA_FLAG_EXEC_DDR is a bit flag supported by TA_FLAGS.
This property flag is currently meaningless in OP-TEE. Nevertheless it shall be set. It is a legacy property flag that aimed at targeting location for the TA execution, internal RAM or external DDR.
Therefore all TAs must set TA_FLAG_EXEC_DDR in TA_FLAGS in their user_ta_header_defines.h header file.
Note: this flag will soon be deprecated.
TA_FLAG_SECURE_DATA_PATH is a bit flag supported by TA_FLAGS.
This property flag claims the secure data support from the OP-TEE OS for the TA. Refer to the OP-TEE OS for secure data path support.
TAs that do not set TA_FLAG_SECURE_DATA_PATH in the value of TA_FLAGS will not be able to handle memory reference invocation parameters that relate to secure data path buffers.
TA_FLAG_REMAP_SUPPORT is a bit flag supported by TA_FLAGS.
This property flag is currently meaningless in OP-TEE and therefore we recommend to not use this flag.
Note: this flag will soon be deprecated.
TA_FLAG_CACHE_MAINTENANCE is a bit flag supported by TA_FLAGS.
This property flag claims access to the cache maintenance API for the TA: TEE_CacheXxxx(). Refer to the OP-TEE to check if cache API support is enabled.
TAs that do not set TA_FLAG_CACHE_MAINTENANCE in the value of their TA_FLAGS will not be able to call the cache maintenance API.