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System

The tailored kernel

The linux-tkg kernel patched for the BC-250, the boot parameters and the kernels to avoid.

The heart of SkillFishOS’s optimizations is a custom-built kernel for the BC-250, based on linux-tkg — a build recipe from the Frogging Family that applies performance- and gaming-oriented patches.

Version and patches

The SkillFishOS kernel is version 7.0.10-skillfishos. On top of the standard linux-tkg patches it includes:

  • the BC-250 frequency-unlock patch (range 350–2230 MHz);
  • the 40-CU patch that enables all of the GPU’s Compute Units;
  • a custom RDSEED-quiet patch that silences a noisy kernel message on this hardware.

The kernel package (image + headers) is published as a release and is held (apt-mark hold) so that a Debian update can’t replace it with an unsuitable kernel. It is the default kernel in GRUB.

Boot parameters (cmdline)

The kernel command line is configured as follows, and every parameter has a precise reason:

mitigations=off
amdgpu.gttsize=6144
ttm.pages_limit=4194304
ttm.page_pool_size=4194304
video=DP-1:e
ParameterWhat it does
mitigations=offdisables Spectre/Meltdown mitigations to maximize performance (an acceptable choice on a home console)
amdgpu.gttsize=6144extends the GTT → Vulkan sees ~13 GiB of memory (useful for AI)
ttm.pages_limit / ttm.page_pool_sizeraise the TTM memory manager limits consistently with the enlarged GTT
video=DP-1:eforce-enables the DisplayPort connector (HPD is broken, see hardware)

Live Compute Units. SkillFishOS no longer uses the amdgpu.bc250_cc_write_mode=3 parameter (which locked 40 CU at boot and blocked runtime changes). The system now boots at the driver baseline (24 CU) and a service routes the 40 CUs live at startup; you can change them without a reboot from the Tuner. See GPU and overclock.

Kernels to avoid

Not all recent kernels work well on this hardware. In particular the 6.15.0–6.15.6 and 6.17.8–6.17.10 series are known to be problematic and should be avoided. SkillFishOS ships its own tested kernel precisely to avoid these regressions — see Updates.

IOMMU

As noted on the hardware page, the IOMMU must never be enabled on the BC-250: it is unstable. The kernel always boots with IOMMU disabled.

Why our own kernel and not XanMod or stock

  • The Debian stock kernel lacks the BC-250 patches (frequency unlock, 40 CU) and follows the regressions above.
  • linux-tkg makes it easy to apply the custom patches and to pick gaming-oriented schedulers and options.
  • Building it ourselves means we update the kernel only when a new version brings real benefits and after testing it on the hardware.

Sources