Glossary
The technical terms of SkillFishOS and the BC-250, briefly explained.
The terms that recur throughout the documentation, each explained in one line. In alphabetical order.
Hardware and APU
APU — Accelerated Processing Unit: a chip that integrates CPU and GPU on the same die. The BC-250 carries a semi-custom AMD one.
BC-250 — the board SkillFishOS runs on: Zen 2 + RDNA 2 APU, 16 GB GDDR6, originally made for mining.
Cyan Skillfish — the code name of the graphics part (GPU) of the BC-250’s APU. Hence the name “SkillFish”.
Oberon — the code name of the CPU part (Zen 2) of the APU.
Compute Unit (CU) — the GPU’s compute blocks. The BC-250 has 40, but exposes fewer by default: SkillFishOS unlocks them all (see kernel).
gfx1013 — the identifier of the BC-250’s GPU architecture (RDNA 2 family). It matters because ROCm doesn’t support it → Vulkan is used instead.
RDNA 2 — the AMD graphics architecture of the GPU (same family as the current consoles).
Zen 2 — the AMD CPU architecture of the APU (6 cores / 12 threads).
GDDR6 — the board’s memory type: fast, here shared between CPU and GPU.
UMA — Unified Memory Architecture: CPU and GPU use the same memory pool (the ~16 GB of GDDR6).
GTT — Graphics Translation Table: a mechanism that lets the GPU use system memory beyond dedicated VRAM. SkillFishOS extends it so Vulkan sees ~13 GiB (useful for AI).
Clocks, voltages, thermals
SMU — System Management Unit: the micro-controller inside the APU that manages clocks and voltages. On the BC-250 control goes only through it, not through standard amdgpu sysfs.
SMU governor — the service (cyan-skillfish-governor) that sets the GPU’s frequency/voltage safe-points.
sclk / mclk — GPU core clock (sclk) and memory clock (mclk). On the BC-250 the mclk is not adjustable.
Undervolt — lowering voltage at the same frequency: same work, less heat and power. See GPU & overclock.
Overclock (OC) — raising clocks above default for more performance.
Vid — the voltage the chip requests at a given frequency. On the BC-250 the hard maximum is 1.325 V.
Thermal-guard — the system watchdog that lowers clocks if 85 °C is exceeded.
Heat-soak — heat build-up that skews “back-to-back” benchmarks: let the card cool between runs.
Silicon lottery — the fact that each chip tolerates different OC/undervolt: that’s why SkillFishOS validates profiles on your card.
System software
Debian sid — Debian’s unstable branch, always up to date but prone to regressions: the base of SkillFishOS (see Updates).
KDE Plasma 6 — the desktop environment used, dressed in a steampunk theme.
linux-tkg — the kernel build recipe (Frogging-Family) the tailored SkillFishOS kernel is based on.
Mesa / RADV — the open-source graphics drivers; RADV is the Vulkan driver used by the BC-250’s GPU.
ROCm — AMD’s “official” compute stack: it does not support gfx1013, so it isn’t used.
Vulkan — the graphics/compute API used for both gaming and AI (Ollama) on the BC-250.
Btrfs — the copy-on-write filesystem with snapshots that provides the “safety net” (see Storage & snapshots).
Snapper — the tool that creates automatic Btrfs snapshots before/after updates.
grub-btrfs — makes snapshots appear in the GRUB menu for boot-time rollback.
APT pinning — holding a package at a verified version, for components that are fragile on this hardware.
reprepro — the tool that manages SkillFishOS’s signed APT repository.
HPD — Hot-Plug Detect: monitor connection detection. On the BC-250 it’s broken → the skillfish-dp-hotswap daemon.
s2idle / suspend — the ACPI sleep states: broken on the BC-250, therefore disabled.
IOMMU — I/O virtualization memory management unit: unstable on the BC-250, never enabled.
Gaming and AI
Proton — Valve’s compatibility layer that runs Windows games on Linux via Steam.
gamescope — Valve’s micro-compositor for gaming (“console” session, FSR1/NIS upscaling).
EmuDeck / ES-DE — emulator installer and frontend for emulation.
FSR / OptiScaler — upscaling technologies. FSR 4 is unavailable (needs RDNA 4); FSR1/NIS or OptiScaler are used.
Ollama / OpenWebUI — backend and interface of the local AI.
qwen3:14b — the reference AI model, running entirely on the GPU.
Tuner — SkillFishOS’s native app to tune the hardware with test-and-rollback (see Native apps).