Two fixes from guybrush01's fp8-weights 5090 run (disc #571), which needed both
to boot the fp8w arm on consumer Blackwell.
1) VLLM_USE_DEEP_GEMM: vLLM's DeepGEMM fp8-GEMM path is built for Hopper (sm_90)
+ datacenter Blackwell (sm_100/103). Consumer Blackwell (5090 / PRO 6000 /
GB10, sm_120/121) has no recipe and hard-fails "recipe not found" at boot.
Add _deepgemm_env: for fp8-weights slugs, inject VLLM_USE_DEEP_GEMM=0 on the
consumer SMs (sm_120/121 confirmed-broken; sm_89 Ada added proactively — it
routes fp8 via Marlin/CUTLASS so disabling is a harmless no-op that pre-empts
the same wall for 4090 owners). Hopper/datacenter untouched. dual/fp8/mtp.yml
gains a pass-through env; both launchers whitelist the export.
2) arch-ab.sh fp8w arm: add --force. vllm/qwen-27b-dual-max is status=experimental
so switch.sh gates it without --force.
test-launch-compat locks 5090/Ada-down / Hopper-keep / non-fp8-skip / user-pin.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EfF565T9eSLaqGzidyJ1Pm
deb58a5f55