When users reported mysterious crashes in the Anukari 3D Physics Synthesizer on Radeon GPUs, developer Evan Balster uncovered a startling reality: AMD's OpenCL drivers were silently aborting processes instead of returning standard error codes. This discovery, made through painstaking hardware testing and debugging, highlights systemic issues in GPU vendor reliability that resonate far beyond a single application.

The Radeon Debugging Odyssey

Balster's investigation began when an Anukari user encountered crashes on a laptop with a Radeon gfx90c GPU. Instrumented logs confirmed that OpenCL's clBuildProgram()—a core function for compiling GPU code—triggered a driver-level abort despite valid arguments. With remote debugging impractical, Balster sourced a used Lenovo Ideapad 5 for hands-on analysis. Under a debugger, the root cause emerged: an LLVM compiler error within AMD's driver, exposed through cryptic output like this:

LLVM ERROR: Cannot select: 0x1ce8fdea678: ch = store 0x1ce8fe462a8...

The error indicated the GPU couldn't handle dynamic memory addressing in kernel arguments—a basic OpenCL capability supported by NVIDIA, Intel, and Apple hardware. Balster noted the absurdity: "It's intern-level code in a Windows kernel driver. Aborting the process instead of returning CL_BUILD_PROGRAM_FAILURE is indefensible."

Why This Matters for Developers

This isn't just about Anukari. The flaw—likely a hardware limitation in older Radeon chips like the gfx90c—reveals how fragile cross-platform GPU development can be. OpenCL specifications imply dynamic offset support, yet inconsistent implementations force developers into costly workarounds. Balster implemented one: shifting small arrays from kernel arguments to constant device memory. While this resolved the crash, it came with performance trade-offs optimized primarily for CUDA backends.

The implications ripple across the industry. As Balster wryly observed, "When people ask why Anukari doesn't officially support Radeon, this is why." Driver instability and hardware fragmentation create minefields for applications relying on standardized APIs. With AMD GPUs powering everything from laptops to cloud instances, such issues amplify technical debt in multi-vendor environments.

Beyond the Workaround

Anukari now runs on Balster's test devices, including the gfx90c and a newer gfx1036 Radeon chip, though performance remains suboptimal. Next steps involve stress-testing Vulkan rendering—another historically problematic area for Radeon. For developers, this saga is a cautionary tale: always validate assumptions about API compliance, especially with AMD's heterogeneous hardware landscape. As GPU acceleration permeates AI and real-time simulation, robust error handling and fallback mechanisms aren't luxuries—they're necessities in an ecosystem where one driver's silent abort can derail an entire project.

Source: Anukari Devlog: Working Better on Some Radeon Chips