DF-5525 fixed (patched iicsmb.ko: kprintf + break instead of panic)
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#sysctl hw.dfa.rdelay=200; /root/df5521_poc fireevent
poc: >>> sysctl hw.dfa.fire_event=153 (unknown event) <<<
hw.dfa.fire_event: 0 -> 0
poc: fire rc=0 (panic expected before this line)      <- NO panic
#dmesg:
df5521: firing iicbus_intr(iicbus0, event=0x99, &c)
iicsmb_intr: unknown event (153)!                      <- kprintf, not panic
df5521: iicbus_intr returned (no fault)
#ls /dev/smb0 -> still present; guest alive; transactions continue.