# DF-4071 — vegam MC-arb timing table KERNEL STACK overflow (pass 2)

File: sys/dev/drm/amd/powerplay/smumgr/vegam_smumgr.c:1287-1315 (walk at 1297-1306)

Build (guest probe): cd /tmp && cc -I/usr/src/sys/dev/drm/amd/powerplay/inc -o probe probe.c
Run: ./probe
Expected: SMU75_Discrete_MCArbDramTimingTable = 640B (entries[8][4] of 20B);
  sclk count=9 -> writes at byte 820 (already 180B past); sclk count=255 -> byte 20,400.
Full trigger needs VegaM GPU + crafted VBIOS pptable (absent). Hardware-gated.