I 'm not quite clear about the extended epid group id got from sgx_get_extended_epid_group_id() function.
It always be 0 on my machine. What is this id used for?
If I launch a same enclave code on a same or different platform, how can I distinguish them?
My previous answer is wrong. I toke the Extended GID as GID. The application uses this value to tell the ISV Service Provider which extended Intel(R) EPID Group to use during remote attestation. When the value is 0, that means Intel IAS is used for enclave verification during remote attestation. When using a different platform, the difference is the GID in msg1.