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DF-1166 fix compile-validation (amdgpu smu7_hwmgr.c)
Guest: DragonFly 6.5-DEVELOPMENT #0, cc 8.3, with-src (unpatched baseline)
========================================================================

[1] APPLY fix.diff (6 hunks: 7 loop clamps + 3 .count clamps across v0/v1):
    cd /usr/src && patch -p1 --forward < /root/df1166.diff  -> all hunks succeeded
    'i < MAX_REGULAR_DPM_NUMBER' count in smu7_hwmgr.c -> 7

[2] INCREMENTAL MODULE BUILD (amdgpu, warm obj -> only smu7_hwmgr.o + relink):
    cd /usr/src/sys/dev/drm/amd && make   (backgrounded, ~50s)
      -> AMDGPU_INC_DONE rc=0
      -> sys/dev/drm/amd/amdgpu/smu7_hwmgr.o rebuilt (71192 bytes) & re-linked
      -> 0 'error:' lines under -Werror

[3] RESULT: fix.diff APPLIES + COMPILES clean (amdgpu module, -Werror).

[4] REVERT (source returned to unpatched baseline):
    cd /usr/src && patch -p1 -R < /root/df1166.diff  -> done
    'i < MAX_REGULAR_DPM_NUMBER' count -> 0 (clean)

RUNTIME: not exercised -- amdgpu not in GENERIC, no AMD GPU on guest (latent).