diff --git a/question.md b/question.md
new file mode 100644
index 000000000000..c60a4508a4ad
--- /dev/null
+++ b/question.md
@@ -0,0 +1,24 @@
+```
+$ make world.opt install
+make -C byterun  all
+make[1]: Entering directory '/data/data/com.termux/files/home/ocaml/byterun'
+gcc -O2 -fno-strict-aliasing -fwrapv -Wall  -g -D_FILE_OFFSET_BITS=64 -D_REENTRANT -DCAML_NAME_SPACE  -Wl,-E -Wl,-E -o ocamlrun prims.o libcamlrun.a -lm  -lcurses -lpthread
+libcamlrun.a(signals.o): In function `caml_try_leave_blocking_section_default':
+/data/data/com.termux/files/home/ocaml/byterun/signals.c:101: undefined reference to `__atomic_exchange_4'
+clang-6.0: error: linker command failed with exit code 1 (use -v to see invocation)
+make[1]: *** [Makefile:181: ocamlrun] Error 1
+make[1]: Leaving directory '/data/data/com.termux/files/home/ocaml/byterun'
+make: *** [Makefile:384: coldstart] Error 2
+
+
+termux 0.63
+
+uname -a
+Linux localhost 3.18.31-perf-g2830021-00101-g31fe6a0 #1 SMP PREEMPT Thu Mar 29 04:06:50 CDT 2018 armv7l Android
+
+branch
+* termux-4.06.1
+
+ld -v                                               
+GNU ld (GNU Binutils) 2.30
+```