[GSD-13006] UR_RESULT_ERROR_DEVICE_LOST and OUT_OF_DEVICE_MEMORY on dual Intel Arc B70 Pro (Battlemage) with Level Zero 1.15.38308

[chmihimabb-max]

Hardware

• GPUs: 2x Intel Arc B70 Pro (Battlemage G31), 32 GB each (64 GB total)
• CPU: Intel 12th Gen (Alder Lake)
• OS: Ubuntu 26.04 LTS, kernel 7.0.0-27

Issue

Using the Level Zero API (via llama.cpp SYCL backend), the following errors occur:

1. UR_RESULT_ERROR_DEVICE_LOST (error 20): When attempting to allocate and initialize buffers on dual GPUs, the device connection is lost. This happens during memset operations after successful device enumeration. Even a single GPU can trigger this when larger allocations are made.

2. UR_RESULT_ERROR_OUT_OF_DEVICE_MEMORY (error 39): Occurs when loading models that should fit within available VRAM (64 GB total across 2 GPUs). The system reports the model at ~33 GB, but fails on allocation.

Stack Trace

The crash originates in ggml_backend_sycl_buffer_clear during memset via a SYCL stream.

Workaround

The Vulkan backend (Mesa 26.0.3) works correctly with dual GPUs on the same hardware. The issue appears specific to the Level Zero / SYCL path.

Willing to help

Happy to provide additional logs, run diagnostic tools, or test patches.

[chmihimabb-max]

https://gist.github.com/chmihimabb-max/bb6fc112b66128ceca8fffbd06fd3ce7

[kgibala]

Hello @chmihimabb-max,

Thank you for your contribution.

Could you please follow the Issue Submission Guide and create an issue based on it?