mxgrub: Unload NVIDIA driver before kexec reboot #559
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NVIDIA GSP-based GPUs (e.g. the A100 in jabberwocky) are not reset by kexec. The GSP firmware and its WPR2 carveout survive into the next kernel, whose freshly-initialised IOMMU then rejects the GPU's stale DMA. The result is an AMD-Vi IO_PAGE_FAULT storm, a GSP exception (Xid 120, load access fault), and RmInitAdapter failing with 0x62 (NV_ERR_RESET_REQUIRED), so nvidia-smi reports "No devices were found". A cold boot is unaffected because the GPU is power-cycled; only the kexec path leaves the device in this wedged state. Unload the NVIDIA driver in cmd_reboot() before handing off to the new kernel, so the driver shuts the GSP down cleanly and the next kernel enumerates a healthy GPU. Guarded on the driver actually being loaded, so it is a no-op on the rest of the fleet, and best effort otherwise: if a module is missing or busy the reboot still proceeds. Resolves: #557 Assisted-by: Claude Opus 4.8 <noreply@anthropic.com>
pmenzel
commented
Jul 29, 2026
| # so nvidia-smi reports "No devices were found". Unloading the driver first | ||
| # lets it shut the GSP down cleanly so the next kernel enumerates a healthy | ||
| # GPU. Best effort: if a module is absent or busy, proceed with the reboot | ||
| # anyway (no worse than not unloading at all). |
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No idea, if we want long comments, so LLMs better understand the code, or if they should be more terse or even removed.
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Tested on jabberwocky, and
nvidia-smiworks afterward.