Fix-validation kernel build (guest /usr/src with fix.diff applied, "Hunk #1
succeeded at 1447"):

$ cd /usr/src && patch -p1 < /tmp/fix.diff
Patching file sys/kern/tty.c using Plan A...
Hunk #1 succeeded at 1447.
done

$ make -j8 nativekernel KERNCONF=X86_64_GENERIC
--------------------------------------------------------------
>>> Kernel build for X86_64_GENERIC completed on Mon Oct 12 20:12:41 UTC 2026
--------------------------------------------------------------
      321.46 real      1387.30 user      263.02 sys
rc=0

$ make installkernel KERNCONF=X86_64_GENERIC
>>> Kernel install for X86_64_GENERIC completed on Mon Oct 12 20:13:51 UTC 2026
rc=0
(rebooted into DragonFly 6.5-DEVELOPMENT #1: Mon Oct 12 20:09:42 UTC 2026)