When pinning GPUs for the llama-server child, the ROCm path set both
HIP_VISIBLE_DEVICES and ROCR_VISIBLE_DEVICES to the same physical
indices. These masks filter at different layers and stack:
ROCR_VISIBLE_DEVICES reduces the visible set at the HSA/ROCr layer and
re-indexes from 0, then HIP_VISIBLE_DEVICES indexes into that reduced
set. _select_gpus ranks by free VRAM and picks the most-free card, so a
single non-zero pin (e.g. "1") becomes out of range at the HIP layer,
HIP enumerates 0 devices, and the model silently runs on CPU
("ggml_cuda_init: failed to initialize ROCm: no ROCm-capable device is
detected").
Set only HIP_VISIBLE_DEVICES (which narrows correctly on its own) and
clear any inherited ROCR mask so it can't double up.
Verified on a 2x Radeon AI PRO R9700 (gfx1201) host, ROCm 7.1.1: the
same selected=[1] load that fell back to CPU (~7.7 tok/s) now runs on
the GPU (~78 tok/s).
Fixes#6175
Co-authored-by: Lee Jackson <130007945+Imagineer99@users.noreply.github.com>
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