> 1. What will the impact be for ROCm's Navi support on Linux?
You will see that supported officially in ROCm 5.0, the next ROCm release. Note that ROCm 5.0 drops support for first generation Vega GPUs. (Radeon Instinct MI25)
The only consumer card to have shipped with second gen Vega is the Radeon VII.
All future plans are subject to change, but official Navi21 support is expected in ROCm 5.0. It's been shipping unofficially since ROCm 4.2.
Official Navi support (5000-series cards), however, is expected in a later release. In current releases, I think the only ROCm library shipping unofficial support is rocBLAS.
(I work for AMD on ROCm. All opinions are my own.)
You will see that supported officially in ROCm 5.0, the next ROCm release. Note that ROCm 5.0 drops support for first generation Vega GPUs. (Radeon Instinct MI25)
The only consumer card to have shipped with second gen Vega is the Radeon VII.