Start using the Intel® Distribution for GDB* for debugging applications. Follow the instructions below to set up the debugger to debug applications with kernels offloaded to CPU and GPU devices.
Intel® Distribution for GDB* is available as part of the Intel® oneAPI Base Toolkit. For more information on oneAPI toolkits, visit the product page.
Visit the Release Notes page for information about key capabilities, new features, and known issues.
You can use a SYCL* sample code, Array Transform, to get started with the Intel® Distribution for GDB*. The sample does not generate errors and simply illustrates debugger features. The code processes elements of the input array depending on whether they are even or odd and produces an output array. You can use the sample to debug on both the CPU or GPU, specifying the chosen device through a command line argument. Note though that GPU debugging may require two systems and additional configuration for remote debugging.
If you aim to debug on GPU, install the latest GPU drivers and configure your system to use them. Refer to the Intel® oneAPI Toolkits Installation Guide for Linux* OS. Follow the instructions Install Intel GPU Drivers to install GPU drivers matching your system.
Additionally, you can install an extension for Visual Studio Code* for debugging GPU with Intel® Distribution for GDB*. Refer to the Using Visual Studio Code with Intel® oneAPI Toolkits Guide.
To set up the GPU debugger, you must have root access.
If you aim to debug on GPU, a Linux Kernel that supports GPU debugging is needed.
Follow the instructions at Intel® software for general purpose GPU capabilities to download and install the necessary drivers.
Enable i915 debug support in Kernel:
Open a terminal.
Open the grub file in /etc/default.
In the grub file, find the line GRUB_CMDLINE_LINUX_DEFAULT="".
Enter the following text between the quotes (""):
i915.debug_eu=1
i915.enable_hangcheck=0
to the same GRUB_CMDLINE_LINUX_DEFAULT line.
Update GRUB for these changes to take effect:
sudo update-grub
Reboot.
Set up your CLI environment by sourcing the setvars script located in the root of your toolkit installation.
Linux (sudo):
source /opt/intel/oneapi/setvars.sh
Linux (user):
source ~/intel/oneapi/setvars.sh
Setup environment
Use the following environment variables to enable debugger support for Intel® oneAPI Level Zero:
export ZET_ENABLE_PROGRAM_DEBUGGING=1 export IGC_EnableGTLocationDebugging=1
System check
When everything is ready, please run the following command to confirm that the system configuration is reliable:
python3 /path/to/intel/oneapi/diagnostics/latest/diagnostics.py --filter debugger_sys_check --force
A possible output of a well configured system is as follows:
... Checks results: =========================================================================================================== Check name: debugger_sys_check Description: This check verifies if the environment is ready to use gdb (Intel(R) Distribution for GDB*). Result status: PASS Debugger found. libipt found. libiga found. i915 debug is enabled. Environmental variables correct. =========================================================================================================== 1 CHECK: 1 PASS, 0 FAIL, 0 WARNINGS, 0 ERRORS Console output file: /path/to/logs/diagnostics_filter_debugger_sys_check_force.txt JSON output file: /path/to/diagnostics/logs/diagnostics_filter_debugger_sys_check_force.json ...
You can use the sample project, Array Transform, to quickly get started with the application debugger.
To get the sample, choose any of the following ways:
Use the oneAPI CLI Samples Browser to select Array Transform from the Getting Started category.
Download from GitHub*.
Navigate to the src of the sample project:
cd array-transform/src
Compile the application by enabling the debug info (-g flag) and turning off optimizations (-O0 flag). Disabling optimization is recommended for a stable and accurate debug environment. This helps to avoid confusion caused by changes to the code after compiler optimizations.
You can compile the program in several ways. Options 1 and 2 use just-in-time (JIT) compilation, which is recommended to debug the sample. Option 3 uses ahead-of-time (AOT) compilation.
Option 1. You can use the CMake file to configure and build the application. Refer to the README of the sample for the instructions.
Option 2. To compile the array-transform.cpp sample application without the CMake file, issue the following commands:
icpx -fsycl -g -O0 array-transform.cpp -o array-transform
If compilation and linking is done separately, retain the -g -O0 flags at the link step. The link step is when icpx translates these flags to be passed to the device compiler at runtime. Example:
icpx -fsycl -g -O0 -c array-transform.cpp icpx -fsycl -g -O0 array-transform.o -o array-transform
Option 3. You can use AOT compilation to avoid longer JIT compilation times at runtime. JIT compilation can take significantly longer for large kernels under the debugger. To use Ahead-of-Time compilation mode:
For debugging on a GPU:
Specify the device that you will use for program execution. For example, -device dg2-g10 for Intel® Data Center GPU Flex 140 Graphics. For the list of supported options and more information on AOT compilation, refer to the Intel® oneAPI DPC++ Compiler Developer Guide and Reference.
For example:
icpx -fsycl -g -O0 -fsycl-targets=spir64_gen -Xs "-device dg2-g10" array-transform.cpp -o array-transform
Ahead-of-Time compilation requires the OpenCL™ Offline Compiler (OC Compiler LOC). For more information, refer the section “Install OpenCL™ Offline Compiler (OCLOC)” of the Installation Guide.
For debugging on a CPU:
icpx -fsycl -g -O0 -fsycl-targets=spir64_x86_64 array-transform.cpp -o array-transform
Start the debug session:
Start Intel® Distribution for GDB* as follows:
gdb-oneapi array-transform
You should see the (gdb) prompt.
To make sure that the kernel is offloaded to the right device, do the following steps. When you execute the run command from the (gdb) prompt, pass the cpu, gpu or accelerator argument:
For debugging on the CPU:
run cpu
Example output:
[SYCL] Using device: [Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz] from [Intel(R) OpenCL]
For debugging on the GPU:
run gpu
Example output:
[SYCL] Using device: [Intel(R) Data Center GPU Flex Series 140 [0x56c1]] from [Intel(R) Level-Zero]
For debugging on the FPGA-emulator:
run accelerator
Example output:
[SYCL] Using device: [Intel(R) FPGA Emulation Device] from [Intel(R) FPGA Emulation Platform for OpenCL(TM) software]
To quit the Intel® Distribution for GDB*:
quit
For your convenience, common Intel® Distribution for GDB* commands are provided in the Reference Sheet.
To debug the Array Transform sample and learn more about Intel® Distribution for GDB*, walk through basic debugging scenarios using the Tutorial.
Document |
Description |
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This document describes the basic scenarios to follow while debugging SYCL* and OpenCL with Intel® Distribution for GDB*. |
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This document describes all common tasks that you can complete with Intel® Distribution for GDB* and provides necessary technical details. |
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The notes contain information about key capabilities, new features, and known issues of Intel® Distribution for GDB*. |
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This page contains brief introduction on oneAPI toolkits and links to useful resources. |
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This one-page document briefly describes Intel® Distribution for GDB* prerequisites and useful commands. |
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This small SYCL* application has two versions: bugged and fixed. Use the sample to exercise application debugging with Intel® Distribution for GDB*. |
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