DF-4582 decisive kernel run — DragonFly 6.5-DEVELOPMENT guest (QEMU/KVM, no AMD GPU):
verbatim rs690_crtc_bandwidth_compute() compiled into a KLD with kernel
flags (-O2 -fno-strict-overflow, kmod.mk), scenario selected at runtime:

  # kldload ./df4582_div0.ko
  # sysctl df4582.run=0        # mode->clock = 1048576 kHz (2^20)

serial console (dfbsd-qemu/vm.sh log):

DF4582-KMOD: loaded; write sysctl df4582.run=<0|1|2>
DF4582-KMOD: scenario 0: entering verbatim rs690_crtc_bandwidth_compute()
DF4582-KMOD: scenario 0: mode.clock=1048576 kHz sideport=0 pm.sclk=400 igp_sideport_mclk=667

Fatal trap 18: integer divide fault while in kernel mode
cpuid = 0; lapic id = 0
instruction pointer	= 0x8:0xffffffff8260000a
stack pointer	        = 0x10:0xfffff801183e76c0
frame pointer	        = 0x10:0xfffff801183e7798
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, long 0, def32 0, gran 1
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 1314
current thread          = pri 6
kernel: type 18 trap, code=0

CPU0 stopping CPUs: 0x0000003e
 stopped
Stopped at      dfixed_div+0xa: divq    %rsi,%eax
db>

=> guest down; vm.sh status: down.
   Trap 18 = integer divide fault (#DE) inside the verbatim dfixed_div.