=== DF-2343/DF-2344 fixed-kernel A/B (-O0 semantics) ===
DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #4: Sun Oct 18 22:16:42 UTC 2026     root@dfbsd:/usr/obj/usr/src/sys/UMCSH  x86_64
1064:	if (rate == 0)		/* no div-by-zero, no divisors[9] OOB read */
325:		device_printf(dev, "failed to read GPIO register\n");
--- DF-2343 fixed: rate==0 now rejected before the loop ---
  rc=0 numports=0 divisor=0 clk=0x00 attached=0 rd=0 wr=0 oob_dword=0x00000000
  rc=4294967295 numports=0 divisor=57005 clk=0xee attached=0 rd=0 wr=0 oob_dword=0x00000000
  rc=0 numports=0 divisor=12 clk=0x00 attached=0 rd=0 wr=0 oob_dword=0x00000000
  rc=22 numports=0 divisor=0 clk=0x00 attached=0 rd=0 wr=0 oob_dword=0x00000000
  rc=22 numports=0 divisor=0 clk=0x00 attached=0 rd=0 wr=0 oob_dword=0x00000000
--- DF-2344 fixed: GPIO failure -> deterministic ENXIO ---
  rc=6 numports=0 divisor=0 clk=0x00 attached=0 rd=1 wr=0 oob_dword=0x00000000
  rc=6 numports=0 divisor=0 clk=0x00 attached=0 rd=1 wr=0 oob_dword=0x00000000
  rc=6 numports=0 divisor=0 clk=0x00 attached=0 rd=1 wr=0 oob_dword=0x00000000
  rc=6 numports=0 divisor=0 clk=0x00 attached=0 rd=1 wr=0 oob_dword=0x00000000
  rc=0 numports=0 divisor=0 clk=0x00 attached=0 rd=1 wr=0 oob_dword=0x00000000
  msg: attached=0 numports=0
--- DF-2344 no-regression: good device still attaches ---
  rc=0 numports=4 divisor=0 clk=0x00 attached=0 rd=2 wr=0 oob_dword=0x00000000
  msg: attached, tty=ucom0
  rc=16 numports=0 divisor=0 clk=0x00 attached=0 rd=0 wr=0 oob_dword=0x00000000
  msg: already attached, run DETACH first
  rc=0 numports=0 divisor=0 clk=0x00 attached=0 rd=0 wr=0 oob_dword=0x00000000
--- DF-2343 fixed: unprivileged first open (was: panic) ---
  rc=0 numports=4 divisor=0 clk=0x00 attached=0 rd=2 wr=0 oob_dword=0x00000000
  msg: attached, tty=ucom0
tioc0: opening /dev/cuaU0.0 (uid=1001) -- sc_it_* untouched, c_ospeed==0 flows to ucom_pre_param on first open
tioc0: open returned fd=3 -- NO PANIC
  post-open termios            ispeed=0 ospeed=0 cflag=0x0
--- TIOCSETA variants still blocked, no panic ---
tioc0: opening /dev/ttyU0.0 (uid=0), then TIOCSETA c_ospeed==0 variants
  current                      ispeed=0 ospeed=0 cflag=0x0
  TIOCSETA sane 19200               -> rc=0 errno=0 (OK)
  TIOCSETA ispeed=0 ospeed=0        -> rc=-1 errno=22 (Invalid argument)
  TIOCSETA ispeed=19200 ospeed=0    -> rc=-1 errno=22 (Invalid argument)
  TIOCSETA CIGNORE ispeed=0 ospeed=0 -> rc=0 errno=0 (OK)
  after variants               ispeed=19200 ospeed=19200 cflag=0x0
tioc0: still alive, no panic
  rc=0 numports=0 divisor=0 clk=0x00 attached=0 rd=0 wr=0 oob_dword=0x00000000
FIXED_RUN_OK