bring up

Each layer depends on the ones below it and a mistake at the bottom shows up six layers higher as something else entirely. The order, the dependency almost everyone gets wrong on Blackwell systems, and the validation ladder that keeps a fault attributable to one node instead of five hundred.

It configures the NVSwitch fabric so eight GPUs present as one NVLink domain, and when it is absent nothing errors. Jobs run, results are correct, and everything multi-GPU is slower by a factor the team spends weeks not finding. The check that takes one command.