https://svn.freebsd.org/base/releng/12.0

make buildkernel

cc -target x86_64-unknown-freebsd12.0 --sysroot=/usr/obj/usr/src/amd64.amd64/tmp -B/usr/obj/usr/src/amd64.amd64/tmp/usr/bin -shared -nostdlib hack.c -o hack.pico
rm -f hack.c
MAKE="/usr/obj/usr/src/make.amd64/bmake" sh /usr/src/sys/conf/newvers.sh "-R" GENERIC
cc -target x86_64-unknown-freebsd12.0 --sysroot=/usr/obj/usr/src/amd64.amd64/tmp -B/usr/obj/usr/src/amd64.amd64/tmp/usr/bin -c -O2 -pipe -fno-strict-aliasing  -g -nostdinc  -I. -I/usr/src/sys -I/usr/src/sys/contrib/ck/include -I/usr/src/sys/contrib/libfdt -D_KERNEL -DHAVE_KERNEL_OPTION_HEADERS -include opt_global.h  -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer  -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float  -fno-asynchronous-unwind-tables -ffreestanding -fwrapv -fstack-protector -gdwarf-2 -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith -Wcast-qual -Wundef -Wno-pointer-sign -D__printf__=__freebsd_kprintf__ -Wmissing-include-dirs -fdiagnostics-show-option -Wno-unknown-pragmas -Wno-error-tautological-compare -Wno-error-empty-body -Wno-error-parentheses-equality -Wno-error-unused-function -Wno-error-pointer-sign -Wno-error-shift-negative-value -Wno-address-of-packed-member  -mno-aes -mno-avx  -std=iso9899:1999 -Werror  vers.c
ctfconvert -L VERSION -g vers.o
linking kernel.full
ctfmerge -L VERSION -g -o kernel.full ...
32768: not found
*** Error code 127

Stop.
bmake[2]: stopped in /usr/obj/usr/src/amd64.amd64/sys/GENERIC
*** Error code 1

Stop.
bmake[1]: stopped in /usr/src
*** Error code 1

Stop.
make: stopped in /usr/src
[root@monitor /usr/src]#