RtlSetSystemGlobalData

INT64 __fastcall RtlSetSystemGlobalData(INT64 a1, UINT64 *a2){
  if( PsIsCurrentThreadInServerSilo() )
    *(_DWORD *)(PsGetCurrentServerSiloGlobals()[141] + 584) = *(_DWORD *)a2;
  else
    KUSER_SHARED_DATA.TimeZoneId = *(_DWORD *)a2;
  return 0i64;
}

Referenced by:

ExpRefreshTimeZoneInformation