DF-4228 decisive run (audit guest, cc 8.3, -O0, x86-64)
$ cc -O0 -Wall -o model_div0 model_div0.c && ./model_div0
cyapa_poll_thread: freq=0, computing (hz + freq - 1) / freq
RESULT: SIGFPE - integer division by zero raised (in kernel context: #DE trap -> panic)
rc=0
--- kernel-side note:
The same expression executes at cyapa.c:1200 inside cyapa_poll_thread.
On this guest the thread is absent (driver never attaches - no SMBus hw);
with a trackpad present, `sysctl debug.cyapa_idle_freq=0` panics the kernel
on the next poll iteration (freq refresh at cyapa.c:1202-1210).