Guest env for DF-2963 (QEMU/KVM, dfbsd-qemu/vm.sh)
=====================================================
Baseline kernel (bug reproduced):
  DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026
      root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC  x86_64
Patched kernel (fix validated):
  DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #1: Fri Sep  4 08:10:58 UTC 2026
      root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC  x86_64
Compiler: cc 8.3 [DragonFly] Release/2019-02-22
vn devices: vnconfig(8); 4 vn slots, none in use during capture.
Test media: /root/df2963.img — 64 MB (131072 x 512B sectors), crafted GPT:
  PMBR (type 0xEE) @ LBA0; header @ LBA1 (128 entries, entsz 128, table @ LBA2..33);
  entry   0 = MS basic data LBA 34..63   -> /dev/vn0s0   (data "ENTRY0ZONE...")
  entry 126 = MS basic data LBA 160..161 -> /dev/vn0s126 (data "ENTRY126ZONE")
  entry 127 = MS basic data LBA 1000..1099 -> /dev/vn0s127 (data "ENTRY127ZONE")