Intel® Distribution for GDB* Release Notes

版本: 2022.2   发布日期: 04/29/2020  

最后更新日期: 04/04/2022

Where to Find the Release

Intel® Distribution for GDB* is available as part of the Intel® oneAPI Base Toolkit. To download the Intel® oneAPI Base Toolkit and learn more about toolkits, visit the Intel® oneAPI Toolkits main page.

Visit Intel® oneAPI Toolkit and Component Versioning Schema for more information about semantic versioning and how it is used with Intel® oneAPI.

Release Notes for Linux* OS

Major Features

  • Multi-target: The debugger can orchestrate multiple targets of different architectures. This feature allows you to debug the "host" portion and the "kernel" of a DPC++ program in the same GDB* session.
  • Auto-attach: The debugger automatically creates an inferior that attaches itself to the Intel® Graphics Technology target to be able to receive events and control the GPU for native debugging.
  • Thread SIMD lanes: The debugger displays SIMD lane information for the GPU threads on the command line interface. You can switch between lanes.
  • Support for debugging a kernel offloaded to a CPU, GPU, or FPGA-emulation device.
  • The debugger is based on the GDB* 11.2 release.

Key Capabilities

  • Support for Intel® Iris® Xe Graphics.
  • Automatically detecting JIT-compiled, or dynamically loaded, kernel code for debugging.
  • Defining breakpoints (both inside and outside of a kernel) to halt the execution of the program.
  • Inspecting and changing the values of variables in the application.
  • Inspecting and changing register values.
  • Listing the threads; switching the current thread context.
  • Listing active SIMD lanes; switching the current SIMD lane context per thread.
  • Evaluating and printing the values of expressions in multiple threads and SIMD lane contexts.
  • Disassembling the machine instructions.
  • Displaying and navigating the function call-stack.
  • Source- and instruction-level stepping.
  • Non-stop and all-stop debug mode.
  • Recording the execution using Intel® Processor Trace (Intel® PT).
  • Printing of Intel® PT PTWRITE payloads in the instruction history and function-call history.
  • Displaying the shadow stack backtrace and Intel® Control-flow Enforcement Technology (Intel® CET) debugging status information.

System Requirements

Documentation

 

  • Various bug fixes and improvements

Changes in the 2022.2 Release

  • Bumped GDB version to 11.2. See changes here.
  • Introduced set|show suppress-cli-notifications commands to suppress notifications to be printed out. Check help suppress-cli-notifications for more info.
  • Added support for function calls in expression evaluation on GPU targets.
  • Fixed an issue with loading shared library symbols for Intel® Graphics Technology remote target on Windows.
  • Fixed an issue with the until command when debugging the same executable within a single session. Now, until is interpreted within the current program space.
  • Fixed a crash in gdbserver-gt when attempting to continue debugged process when it has died.
  • Fixed an error when attempting to re-run the executable while the offloaded GPU kernel inferior is the current context.
  • Intel® Graphics Technology-specific performance improvements.
  • Stability improvements.
  • Deprecated the printing of Intel® TSX abort reasons (info tsx-abort-reason). This feature will be removed in the 2022.3 release.
  • Added DG2 support (beta). Known issues:
    • Conditional breakpoints may not work as expected.
    • Function calls in expression evaluation do not work correctly.
  • Fixed asynchronous MI mode, now one can use set mi-async on.

 

Known Issues and Limitations

  • For OpenMP* #pragma omp single blocks in C++, private variables cannot be inspected and breakpoints may occasionally not hit the expected line.

  • During the expression evaluation, an element of an accessor object cannot be accessed using the multi-dimensional access syntax. See an error example below:
(gdb) print anAccessor[5][3][4]
Cannot resolve function operator[] to any overloaded instance


You can use the id object instead:

(gdb) print workItemId
$1 = cl::sycl::id<3> = {5, 3, 4}
(gdb) print anAccessor[workItemId]
$2 = 1234

On GPU devices:

  • Inferior calls (invocation of kernel functions from inside the debugger for expression evaluation) are not supported.
  • GDB might occasionally return the message "Cannot execute this command while the target is running". Ignore the message as it should not affect further debugging.
  • If you define a breakpoint at a location before a kernel (inside the host code), the breakpoint is also defined at the start of the kernel. This is similar to defining a breakpoint at a comment line or an empty line: in these cases, the breakpoint is defined for the next source line.
  • If the currently selected SIMD lane of a thread becomes inactive, GDB might silently switch the focus to the first active SIMD lane in this thread.
  • For Gen12 devices, the number of SIMD lanes is incorrectly shown.
  • Ahead-of-time compilation is supported but the code must be built with the -cl-kernel-debug-enable flag.
  • Inspecting shared-local-memory (SLM) is not supported.
  • Applications that use unified shared memory (USM) may appear as raising a SIGSEGV when a USM-allocated memory is being accessed. This is a mechanism used by the runtime to trigger memory migration. In such cases, sending the signal back to the application resumes the program. For this, use GDB's signal SIGSEGV command.
  • Restarting the debugged program while the current context is the host inferior may cause GDB and gdbserver-gt to become out-of-sync. This may require a complete restart of the debugging session to regain the full debugging ability.

On CPU and GPU devices:

  •  Debugging OpenMP kernel code for Fortran (#pragma omp target) is not supported.

Release Notes for Windows* OS

Major Features

  • Support for debugging a kernel offloaded to a CPU, GPU, or FPGA-emulation device.

  • Integration into Microsoft Visual Studio* interface to enable GPU remote debugging. This feature allows you to debug the "host" portion and the "kernel" of a DPC++ program in the same VS remote debugging session. 

Key Capabilities

  • Inserting a breakpoint inside a kernel and stopping when the breakpoint is hit by a thread
  • Inspecting local variables
  • Source-level stepping
  • Backtracing function calls
  • Examining threads
  • Reading registers
  • Disassembling
  • Automatic launch of gdbserver-gt
  • Support for debugging OpenCL and DPC++ programs
  • Support for debugging OpenMP* C++ kernel code for CPU and GPU offloads.

System Requirements

You can download the latest driver at Intel® Graphics - Windows® 10 DCH Driver.

Documentation

To set up the debugger, refer to the Get Started with Debugging Data Parallel C++. If you are more comfortable with the video format, refer to the getting started video.

  • Support for Microsoft Visual Studio* 2022.

Changes in the 2022.2 Release

  • Removed support for Visual Studio* 2017.
  • Addressed the issue where the user was unable to connect and debug a target outside the domain network.
  • GPU thread names are now accessible in the application debug process in Visual Studio Code* (VS Code).

Known Issues and Limitations

On GPU devices:

  • The target system might lose the network connection after the debugging session is started. In this case, reboot the target system.
  • Microsoft Visual Studio* interface does not support viewing SIMD lanes.
  • In Microsoft Visual Studio*, the following message might be displayed "Cannot execute this command while the target is running". Ignore the message as it should not affect further debugging.
  • If you define a breakpoint at a location before the kernel (inside the host code), the breakpoint is also defined at the start of the kernel. This is similar to defining a breakpoint at a comment line or an empty line: in these cases, the breakpoint is defined for the next source line.
  • After hitting a breakpoint defined before a kernel, not all threads hit a breakpoint defined inside the kernel.
  • Single steps on the last line of a kernel lead to the termination of the program being debugged.
  • For debugging on a GPU, you should use a grid size of 256 or fewer work items.
  • Inferior calls (invocation of kernel functions from inside the debugger for expression evaluation) are not supported.
  • Kernel functions are inlined by the compiler. Breakpoints on calls to inlined functions may not be hit. Try placing breakpoints before the call or inside the called function​.
  • For OpenMP you need to start the gdbserver-gt manually with IPv4:
$ gdbserver-gt --hostpid=1 --attach 127.0.0.1:1234 1
 

On CPU and GPU devices:

  •  Debugging OpenMP kernel code for Fortran (#pragma omp target) is not supported.
  • For OpenMP #pragma omp single blocks in C++, private variables cannot be inspected and breakpoints may occasionally not hit the expected line.

On FPGA emulator devices:

  • For debugging on FPGA emulator, ahead-of-time (AoT) compilation is not supported. Ensure that in Project Properties > DPC++   Enable FPGA Workflows is set to no.

  • For debugging on an FPGA emulator, no support for OpenMP.

On CPU devices and FPGA emulator devices:

  • It is recommended to disable the GPU debugger for smooth debugging on CPU and FPGA emulator devices.

Previous oneAPI Releases

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