GNAT User’s Guide Supplement for Cross Platforms

GNAT, The GNU Ada Development Environment

GNAT Pro Edition

Version 26.0w

Date: Jul 21, 2025

AdaCore

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with the Front-Cover Texts being “GNAT User’s Guide for Native Platforms”, and with no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License.

• 1. About This Guide
  • 1.1. What This Guide Contains
  • 1.2. What You Should Know before Reading This Guide
  • 1.3. Related Information
  • 1.4. Conventions
• 2. Introduction to GNAT for Cross Platforms
  • 2.1. Toolchain for Cross Platforms
  • 2.2. Specifying the Target
  • 2.3. Specifying the Run-Time Library
  • 2.4. GNAT C/C++ for Cross Platforms
    • 2.4.1. Supported C++ Version
    • 2.4.2. Mixed-Language Programming using GNAT Exclusively
• 3. The Primary and Secondary Stacks
  • 3.1. The Primary Stack
    • 3.1.1. The Default Primary Stack Size
    • 3.1.2. Per-Task Primary Stack Size
    • 3.1.3. Environment Task Primary Stack Size
  • 3.2. The Secondary Stack
    • 3.2.1. Dynamically-Sized Secondary Stacks
    • 3.2.2. Fixed Secondary Stacks
    • 3.2.3. Disabling the Secondary Stack
• 4. Predefined Profiles
  • 4.1. The Ravenscar Profile
  • 4.2. The Jorvik Profile
    • 4.2.1. Number of Entries Per Protected Object
    • 4.2.2. Number of Queued Callers per Entry
    • 4.2.3. Entry Barriers
    • 4.2.4. Relative Delay Statements
    • 4.2.5. Additional Non-Tasking Restrictions Removed
• 5. Predefined GNAT Pro Run-Times
  • 5.1. Standard Run-Time
  • 5.2. Embedded Run-Time
  • 5.3. Light Run-Time
    • 5.3.1. Allocator Support
    • 5.3.2. Certification
    • 5.3.3. Excluding the Run-Time Library
    • 5.3.4. Exceptions and the Last Chance Handler
    • 5.3.5. Foreign Threads
  • 5.4. Light-Tasking Run-Time
  • 5.5. Specifying a Run-Time
• 6. The GNAT Configurable Run-Time Facility
  • 6.1. Standard Run-Time
  • 6.2. The Configurable Run-Time
  • 6.3. Run-Time Libraries and Objects
    • 6.3.1. GNAT Run-Time Library
    • 6.3.2. C Library
    • 6.3.3. Math Library
    • 6.3.4. Internal GCC Library
    • 6.3.5. Startup and Cleanup Code
  • 6.4. Run-Time Dependencies in User Code
    • 6.4.1. Explicit with Clauses
    • 6.4.2. Compiler-Generated Calls to the GNAT Run-Time Library
    • 6.4.3. Pragma Import
    • 6.4.4. Back-End Generated Calls to Library Functions
  • 6.5. How The Run Time Library Is Configured
    • 6.5.1. Configuration Pragmas
    • 6.5.2. Specification of Configuration Parameters
    • 6.5.3. Restricting the Set of Run-Time Units
  • 6.6. Naming the Run-Time Library
  • 6.7. Creating a Configurable Run-Time Library
• 7. Support for Certified Systems
  • 7.1. The Certification Philosophy
  • 7.2. Using GNAT Pro Features Relevant to Certification
    • 7.2.1. Exceptions
    • 7.2.2. Allocators
    • 7.2.3. Array and Record Assignments
    • 7.2.4. Object-Oriented Programming
    • 7.2.5. Functions Returning Unconstrained Objects
    • 7.2.6. Controlling Implicit Conditionals and Loops
    • 7.2.7. Controlling Use of Conditional Operators
    • 7.2.8. Avoiding Elaboration Code
    • 7.2.9. Removal of Extraneous Code
    • 7.2.10. Traceability from Source Code to Object Code
    • 7.2.11. Optimization issues
    • 7.2.12. Other useful features
    • 7.2.13. Program Build Options

• A. VxWorks Topics
  • Common VxWorks Topics
    • VxWorks VSB Requirements
    • VxWorks Kernel Requirements
    • Executing a Program on VxWorks
    • Mixed-Language Programming on VxWorks using GNAT Exclusively
    • Mixed-Language Programming using the VxWorks C/C++ Compilers
    • Interoperability with VxWorks C/C++ Compilers
    • Known Incompatibilities on VxWorks between LLVM and GNAT
    • Exception Handling
    • Kernel Configuration for VxWorks
    • Main Task Attributes and the Application Stub
    • Stack Overflow Checking on VxWorks
    • Interrupt Handling for VxWorks
    • Handling Relocation Issues for PowerPC Targets
    • Calling exported Ada procedures from the VxWorks shell
    • Simulating Command Line Arguments for VxWorks
    • Traceback Support on VxWorks
    • Using addr2line on VxWorks
    • Removal of Unused Code and Data
    • Debugging
    • Frequently Asked Questions for VxWorks
    • SMP Support
  • Workbench / VxWorks 7 Topics
    • Using GNAT for VxWorks 7
    • Building a VxWorks 7 Application
    • VxWorks 7 SMP Support
    • Debugging an Application on VxWorks 7
    • Using VxSim on VxWorks 7
    • Known GNAT C++ Limitations on VxWorks 7
  • Helix Virtualization Platform Topics
    • Introduction
    • Running and Debugging Applications
    • Application Design Considerations
• B. Deos Topics
  • Supported Run-Time Libraries
  • Deos Configuration and Component Dependencies
  • Getting Started with an Ada application on Deos
  • Mixed Language Programming
  • Ada.Text_IO on Deos
    • Using the Static Video Library
    • Using the Virtual File Library
    • Using Custom I/O Driver
• C. Bareboard Ada Topics
  • Introduction
  • Bareboard Run-Time Libraries
    • Generic bareboard Light run-times
  • Getting Started with the Bareboard Toolchain
  • Linker Scripts
  • Minimizing Object Code and Data Sizes
  • Viewing Object Code and Data Sizes
  • Stacks
  • Character Input/Output
  • Floating-Point Support
  • Dynamic Memory Allocation
  • Bareboard Debugging
  • Non-Symbolic Traceback
• D. Bareboard C and C++ Topics
  • Introduction
  • Bareboard C++ Run-Time Libraries
  • NewLib
  • Exceptions
  • C/C++ Compiler Configuration
  • Startup and Linker Files
  • Example_Project
• E. Customized Bareboard Run-Time Libraries
  • Rationale for A New Run-Time Library
    • Hardware Considerations
    • Software Considerations
  • The Run-Time Library Structure
  • Building A Run-Time Library
    • Building
    • Choosing the Location
  • Example: Creating An STM32F429 Run-Time
    • Initial Library Creation
    • Tailoring the Library
    • Augmenting the Library
• F. ARM-ELF Topics and Tutorial
  • Supported Processors and Run-Time Libraries
    • Generic core runtimes
    • Microcontroller runtimes
  • Getting Started
    • Getting Started with the STM32F429-Discovery
    • Host Setup
    • Opening the Led_Flasher Project
    • Building
    • Running the Program
    • Debugging the Program
  • Changing Time Resolution
  • Target Restrictions
    • Task Priority Restriction
  • Debugging
    • Debugging with GNAT Studio
    • ST Microelectronics Discovery Kits
• G. ARM AARCH64-ELF Topics
  • Supported Processors and Run-Time Libraries
  • Getting Started with the UltraZed and GNAT
    • Preparation
    • Gnatbench Installation
    • Create an Ada Project
    • Run/Debug the Application
  • Resources used by the runtime
  • Memory mapping
  • Boot
  • Debugging
    • Halting time when debugging
• H. LEON3 Topics
  • Supported Processors and Run-Time Libraries
  • Getting Started
  • Executing and Debugging on Emulators
  • Executing and Debugging on Hardware Platforms
  • SMP Support
  • Adapting the Run-Time System
  • LEON3FT RETT Restart Errata
  • Console Output
• I. Morello-ELF Topics
  • CHERI Support
    • CHERI Capabilities
    • CHERI Exceptions
  • Supported Processors and Run-Time Libraries
    • Resources used by the runtime
    • System Clocks
    • Startup Code
    • Memory
    • Interrupts
    • Power Management
    • Text_IO
  • Getting Started
    • GNATemulator
    • Arm Morello System Development Platform
• J. RISC-V 32-Bit ELF Topics
  • Supported Processors and Run-Time Libraries
    • Generic core runtimes
    • Microcontroller runtimes
  • Getting Started
    • Getting Started with GNATemulator
    • Creating a new Project
    • Building
    • Running the Program
    • Debugging the Program
• K. RISC-V 64-Bit ELF Topics
  • Supported Processors and Run-Time Libraries
    • Generic core runtimes
    • Processor runtimes
  • Getting Started
    • Getting Started with GNATemulator
    • Creating a new Project
    • Building
    • Running the Program
    • Debugging the Program
• L. x86_64 ELF Topics
  • Supported Processors and Run-Time Libraries
    • Required CPU Features
    • Running a x86_64-elf Application
    • Serial I/O
    • Clock Speed
    • Interrupts
    • Memory Layout
  • Getting Started
    • Getting Started with GNATemulator
    • Creating a new Project
    • Building
    • Running the Program
    • Debugging the Program
• M. Cross Linux Topics
  • Building a Cross Linux Application
  • Debugging an Application on Cross Linux
• N. PikeOS Topics
  • Kernel Configuration for PikeOS
    • Creating a PikeOS kernel integration project
    • PikeOS maximum priority setting
    • PikeOS interrupts
    • PikeOS Native Personality Extensions
    • PikeOS muxa configuration
  • Building an Ada application on PikeOS
  • Running an Ada application on PikeOS
  • Debugging an Ada application on PikeOS
• O. QNX Topics
  • Getting Started
  • Integration with Momentics
  • Known Issues
    • Debugger Unable to Locate Source File
    • Stack Size insufficient causing Storage Error or memory fault
    • Scheduling Errors when Using Pthreads (QNX 8.0)
• P. RTEMS Topics
  • Getting Started
  • Kernel Configuration
  • Interrupts
  • Using LibBSD with GNAT Pro
  • Debugging
• Q. FreeRTOS Topics
  • Supported Run-Time Libraries
  • Supported Targets
  • FreeRTOS Integration and Dependencies
  • Getting Started with an Ada application on FreeRTOS
  • Ada.Text_IO on FreeRTOS
  • Foreign Thread Support on Light
• R. GNU Free Documentation License