【FF-A】第十四章 Setup and discovery interfaces

本文档详细介绍了FF-A(Firmware Framework Architecture)中的Setup和Discovery接口,包括FFA_VERSION、FFA_FEATURES等接口的使用、功能和兼容性要求。FF-A是一个在ARM TrustZone环境中用于安全软件的框架,这些接口用于不同组件间版本的探测和兼容性检查,确保安全分区的正确运行。

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Chapter 14 Setup and discovery interfaces

14.1 Compliance requirements

表14.1:发现和设置接口

该表列出了在给定的FF-A实例中必须使用特定导管实现的发现和设置接口。

  1. 在表中未列出但在相应接口描述中列出的接口和导管组合是可选的。
  2. 在表14.1和相应接口描述中均未列出的接口和导管组合不受支持。
    在这里插入图片描述
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14.2 FFA_VERSION

Description

FFA_VERSION函数

  • 返回FF-A实例中Firmware Framework实现的版本,如14.2.1概述中所述。
  • 表14.3列出了有效的FF-A实例和导管。
  • 该函数的语法在表14.4中描述。
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### ROS2 Built-in Interfaces Documentation and Usage In the context of ROS2, built-in interfaces play a crucial role in facilitating communication between nodes through standardized message types. The `builtin_interfaces` package provides fundamental data structures that are essential across various parts of ROS2 systems[^1]. #### Key Features of Builtin Interfaces The primary purpose of `builtin_interfaces` is to define common datatypes used throughout ROS2. These include: - **Time**: Represents time with nanosecond precision. - **Duration**: Used for representing durations or timeouts. These definitions ensure consistency when handling temporal information within different components of ROS2 applications. #### Using Time Messages To work with timestamps effectively, developers can utilize the following methods provided by `builtin_interfaces/msg/Time`: ```cpp // C++ example showing how to use Time messages from builtin_interfaces #include "rclcpp/rclcpp.hpp" #include "builtin_interfaces/msg/time.hpp" int main(int argc, char * argv[]) { rclcpp::init(argc, argv); auto node = rclcpp::Node::make_shared("time_example_node"); // Create an instance of Time message type builtin_interfaces::msg::Time current_time; // Set seconds and nanoseconds fields manually current_time.sec = static_cast<int32_t>(std::chrono::system_clock::now().time_since_epoch().count() / 1e9); current_time.nanosec = static_cast<uint32_t>((std::chrono::system_clock::now().time_since_epoch().count() % 1000000000)); RCLCPP_INFO(node->get_logger(), "Current system time: sec=%d nsec=%u", current_time.sec, current_time.nanosec); rclcpp::shutdown(); return 0; } ``` This code snippet demonstrates creating and populating a `Time` object using standard library functions alongside ROS2-specific constructs[^2]. #### Handling Duration Messages Similarly, working with intervals requires understanding the structure offered under `builtin_interfaces/msg/Duration`. Here’s another practical application scenario involving duration manipulation: ```cpp // Example demonstrating usage of Duration messages from builtin_interfaces #include "rclcpp/rclcpp.hpp" #include "builtin_interfaces/msg/duration.hpp" void set_duration(builtin_interfaces::msg::Duration &duration_msg, int64_t ns) { duration_msg.sec = static_cast<int32_t>(ns / 1&#39;000&#39;000&#39;000L); // Convert nanoseconds into whole seconds duration_msg.nanosec = static_cast<uint32_t>(ns % 1&#39;000&#39;000&#39;000L); // Remaining part as fractional second (nanoseconds) } int main() { // Initialize ROS client library... // Define some timeout period expressed in nanoseconds const int64_t TIMEOUT_NS = 5_000_000; // Five milliseconds // Prepare corresponding Duration message container builtin_interfaces::msg::Duration my_timeout{}; // Populate it via helper function defined above set_duration(my_timeout, TIMEOUT_NS); // Use this value wherever needed inside your program logic... return EXIT_SUCCESS; } ``` By leveraging these utilities, programmers gain more control over timing aspects while ensuring compatibility among diverse software modules operating on top of ROS2 infrastructure[^3]. --related questions-- 1. How does one integrate custom message types with existing ones like those found in `builtin_interfaces`? 2. What other core packages besides `builtin_interfaces` form the backbone of inter-node communications in ROS2? 3. Can you provide examples where precise timestamp management becomes critical during real-world robotics operations? 4. Are there any performance implications associated with frequent conversions between native C++ chrono representations and their equivalents available through `builtin_interfaces`?
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