DF-4012 + DF-4020 combined fix-kernel build record (guest /tmp/fixbuild.log
was lost to the validation reboot; decisive lines captured in-session):

$ cd /usr/src && git apply fix4012.diff && git apply fix4020.diff
APPLIED-4012
APPLIED-4020
  sys/dev/raid/mps/mps_user.c:1962:  u_long regs_size;
  sys/dev/raid/mps/mps_user.c:1973:  regs_size = rman_get_size(sc->mps_regs_resource);
  sys/dev/raid/mps/mps_user.c:1974:  if (data->RegOffset >= regs_size)
  sys/dev/raid/mpr/mpr_user.c:2181:  u_long regs_size;
$ make nativekernel KERNCONF=X86_64_GENERIC
  ... 1347 translation units, no errors ...
  >>> Kernel build for X86_64_GENERIC started  on Mon Oct 12 05:03:43 UTC 2026
  >>> Kernel build for X86_64_GENERIC completed on Mon Oct 12 05:22:34 UTC 2026
$ make installkernel KERNCONF=X86_64_GENERIC
  >>> Kernel install for X86_64_GENERIC completed on Mon Oct 12 05:34:27 UTC 2026
$ reboot -> kern.version: DragonFly 6.5-DEVELOPMENT #1: Mon Oct 12 05:11:38 UTC 2026
  root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC
  mps_ioctl_devsw @ 0xffffffff805b16f0 (fixed; prologue 55 48 89 e5 41 57 41 56 unchanged)
  mpr_ioctl_devsw @ 0xffffffff80598ab0 (fixed)