Why nvidia_peermem Fails on DGX Spark: a Deep Dive into GPUDirect RDMA, Secure Boot, and Unified Memory
I chased a modprobe error across two DGX Spark nodes, peeled back layers of Secure Boot signing and kernel build flags, read the nvidia_peermem source code, and discovered that GPUDirect RDMA is architecturally unsupported on the GB10 Grace Blackwell SoC. Here’s the full story.