fix_build.log — recovered from session transcript (the guest's /tmp was
cleared by the reboot before the log could be harvested; the build itself
ran to completion, rc=0, -Werror clean).

$ cd /usr/src && patch -p1 < /tmp/rngtest/fix.diff
Hmm...  Looks like a unified diff to me...
Patching file sys/kern/subr_csprng.c using Plan A...
Hunk #1 succeeded at 129.
done
PATCHED

$ cd /usr/src && make nativekernel KERNCONF=X86_64_GENERIC
   (full log lost with /tmp; final output:)
cc  -O2 -pipe   -D_KERNEL -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes  -Wmissing-prototypes -Wpointer-arith -Wcast-qual -Wold-style-definition -Wmissing-include-dirs -Wno-pointer-sign -Winit-self -Wundef -Wno-unused-but-set-variable -std=gnu11 -Werror -DKLD_MODULE -nostdinc  -I. -Idragonfly -I/usr/obj/usr/src/sys/X86_64_GENERIC -I/usr/obj/usr/src/sys/X86_64_GENERIC/include -Idragonfly/../include -DHAVE_KERNEL_OPTION_FILES -include /usr/obj/usr/src/sys/X86_64_GENERIC/opt_global.h -g -Wold-style-declaration -fno-common -ffreestanding -fno-stack-protector -fno-strict-aliasing -fno-strict-overflow -fno-asynchronous-unwind-tables -fno-omit-frame-pointer -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float -mno-fp-ret-in-387 -mindirect-branch=thunk-inline   -c iconv_converter_if.c
cc -Wl,--build-id=sha1 -nostdlib -Wl,--hash-style=sysv   -r -Wl,-d -o libiconv.ko iconv.o iconv_ucs.o iconv_xlat.o iconv_xlat16.o iconv_converter_if.o
<=== libiconv
--------------------------------------------------------------
>>> Kernel build for X86_64_GENERIC completed on Sun Oct 11 16:18:36 UTC 2026
--------------------------------------------------------------
rc=0

$ cp /boot/kernel/kernel /boot/kernel/kernel.unpatched
$ cp /usr/obj/usr/src/sys/X86_64_GENERIC/kernel.stripped /boot/kernel/kernel
$ cp /usr/obj/usr/src/sys/X86_64_GENERIC/kernel.debug /boot/kernel/kernel.debug
INSTALLED
$ reboot

$ uname -a
DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #1: Sun Oct 11 16:07:34 UTC 2026
     root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC  x86_64
(patched; baseline kernel was "#0: Thu Jul  2 06:02:54 UTC 2026")