========================================================================
DF-1146 fix compile-validation  (i915 i915_gem.c)
Guest: DragonFly 6.5-DEVELOPMENT #0, cc 8.3, with-src snapshot (unpatched)
========================================================================

[1] BASELINE: full i915.ko built clean from /usr/src under -Werror
    (includes i915_gem.o baseline = 117984 bytes)
    $ cd /usr/src/sys/dev/drm/i915 && make
    rc=0 ; i915.ko produced (2146968 bytes), no error:/warning:

[2] APPLY fix.diff:
    $ cd /usr/src && patch -p1 --forward < /root/df1146.diff
    Patching file sys/dev/drm/i915/i915_gem.c using Plan A...
    Hunk #1 succeeded at 2263.
    Hunk #2 succeeded at 2402.
    done

[3] INCREMENTAL REBUILD of patched i915_gem.c:
    $ cd sys/dev/drm/i915 && rm -f i915_gem.o && make i915_gem.o
    cc -O2 -pipe ... -std=gnu11 -Werror -DKLD_MODULE ... \
       -c /usr/src/sys/dev/drm/i915/i915_gem.c
    (no error:/warning: emitted under -Werror)

[4] RESULT:
    /usr/obj/usr/src/sys/dev/drm/i915/i915_gem.o
      baseline  = 117984 bytes
      patched   = 118080 bytes   (+96 bytes from added bounds check + partial offset)
    => fix.diff APPLIES + COMPILES clean.

[5] REVERT (source returned to unpatched baseline):
    $ cd /usr/src && patch -p1 -R < /root/df1146.diff
    Hunk #2 succeeded at 2388. ... done
    grep -c "Reject faults beyond" i915_gem.c  ->  0  (clean)

RUNTIME: not exercised -- no Intel i915 GPU on guest (latent). See run.sh / VERDICT.md.