# DF-2343 environment

Guest: QEMU/KVM x86_64, 6 vCPU, 4 GB RAM, DragonFly 6.5-DEVELOPMENT
Kernel (harness): DragonFly dfbsd 6.5-DEVELOPMENT #N: Sun Oct 18 2026
  root@dfbsd:/usr/obj/usr/src/sys/UMCSH  x86_64
  (X86_64_GENERIC + device ucom + device umcs_harness; stock kernel
  build flags: CCVER=gcc80 -O2 -Werror ...; verbatim umcs.c optionally
  wrapped in #pragma GCC optimize("O0") for the -O0 semantics runs)
Stock kernel for reference: X86_64_GENERIC #0 Thu Jul  2 06:02:54 UTC 2026
Compiler: cc 8.3 [DragonFly] Release/2019-02-22
Verbatim gate: sys/bus/u4b/serial/umcs.c sha256
  33f9ea999efb8aa68ae520a86023c88affe64b71ddf692c786f36f7c172bef67
  (guest /usr/src == host audit tree, byte-identical)
Console: serial (comconsole); panics dumped to /dev/vbd0s1b and the
serial log (dfbsd-qemu/boot.log) is the captured evidence
debug.debugger_on_panic=0
USB hardware: none (QEMU default) — driver exercised via the harness
  fabricated device; ucom/usb core compiled in ("device usb" is in
  X86_64_GENERIC, "device ucom" added by the harness config)
Trigger users: root, and maxx (uid=1001, added to dialer(68) for the
  cuaU0.0 first-open trigger)