# Can't compile Crystal 1.2.2 on 32-bit ARM (armv7l) device: undefined reference to \`\_\_multi3'

**URL:** <https://forum.crystal-lang.org/t/cant-compile-crystal-1-2-2-on-32-bit-arm-armv7l-device-undefined-reference-to-multi3/4077>\
**Category:** Help & Support\
**Created:** [November 21, 2021, 12:32am UTC](https://forum.crystal-lang.org/t/cant-compile-crystal-1-2-2-on-32-bit-arm-armv7l-device-undefined-reference-to-multi3/4077 "2021-11-21T00:32:11Z")\
**Posts on this page:** 9\
**Page:** 1

<div class="post-metadata">

**Author:** ![thesseyren](https://avatars.discourse-cdn.com/v4/letter/t/dc4da7/32.png) [@thesseyren](https://forum.crystal-lang.org/u/thesseyren)\
**Post date:** [November 21, 2021, 12:32am UTC](https://forum.crystal-lang.org/t/cant-compile-crystal-1-2-2-on-32-bit-arm-armv7l-device-undefined-reference-to-multi3/4077/1 "2021-11-21T00:32:11Z")

</div>

Hello everyone. I can’t compile crystal on my armv7l device with Ubuntu 20.04. Here are the steps that I followed:

Some info about my `x86_64` device:

```auto
thesseyren@x86_64:~$ uname -a
Linux tsslenovo 5.4.0-90-generic #101-Ubuntu SMP Fri Oct 15 20:00:55 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
thesseyren@x86_64:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.3 LTS
Release: 20.04
Codename: focal
thesseyren@x86_64:~$ crystal -v
Crystal 1.2.2 [6529d725a] (2021-11-10)

LLVM: 10.0.0
Default target: x86_64-unknown-linux-gnu

```

Version list of required libraries on `x86_64`:

```auto
||/ Name Version Arch
+++-===================-============================-============-
ii automake 1:1.16.1-4ubuntu6 all         
ii build-essential 12.8ubuntu1.1 amd64       
ii crystal 1.2.2-1+1.1 amd64 (from official crystal deb repository)
ii libbsd-dev:amd64 0.10.0-1 amd64       
ii libedit-dev:amd64 3.1-20191231-1 amd64       
ii libevent-dev 2.1.11-stable-1 amd64       
ii libgc-dev:amd64 1:7.6.4-0.4ubuntu1 amd64       
ii libgc1c2:amd64 1:7.6.4-0.4ubuntu1 amd64       
ii libgmp-dev:amd64 2:6.2.0+dfsg-4 amd64       
ii libgmpxx4ldbl:amd64 2:6.2.0+dfsg-4 amd64       
ii libpcre3-dev:amd64 2:8.39-12build1 amd64       
ii libssl-dev:amd64 1.1.1f-1ubuntu2.9 amd64       
ii libtool 2.4.6-14 all         
ii libxml2-dev:amd64 2.9.10+dfsg-5ubuntu0.20.04.1 amd64       
ii libyaml-dev:amd64 0.2.2-1 amd64       
ii lld-12 1:12.0.0-3ubuntu1~20.04.4 amd64       
ii llvm-12 1:12.0.0-3ubuntu1~20.04.4 amd64       
ii llvm-12-dev 1:12.0.0-3ubuntu1~20.04.4 amd64       

```

I did these on `x86_64`:

```auto
thesseyren@x86_64:~$ sudo ln -sf /usr/bin/ld.lld-12 /usr/bin/ld.lld
thesseyren@x86_64:~$ git clone https://github.com/crystal-lang/crystal.git
thesseyren@x86_64:~$ cd crystal/
thesseyren@x86_64:~/crystal$ git checkout 1.2.2
thesseyren@x86_64:~/crystal$ make release=1 progress=1 target=armv7l-unknown-linux-gnueabihf
Using /usr/bin/llvm-config-12 [version=12.0.0]
g++ -c -o src/llvm/ext/llvm_ext.o src/llvm/ext/llvm_ext.cc -I/usr/lib/llvm-12/include -std=c++14 -fno-exceptions -D_GNU_SOURCE -D __STDC_CONSTANT_MACROS -D__ STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
CRYSTAL_CONFIG_BUILD_COMMIT="6529d725a" CRYSTAL_CONFIG_PATH='$ORIGIN/../share/crystal/src' SOURCE_DATE_EPOCH="1636546449" CRYSTAL_CONFIG_LIBRARY_PATH='$ORIGIN/../lib/crystal' ./bin/crystal build --release --progress --cross-compile --target armv7l-unknown-linux-gnueabihf -o .build/crystal src/compiler/crystal.cr -D without_openssl -D without_zlib
cc .build/crystal.o -o .build/crystal -rdynamic -L/usr/bin/../lib/crystal src/llvm/ext/llvm_ext.o `"/usr/bin/llvm-config-12" --libs --system-libs --ldflags 2> /dev/null` -lstdc++ -lpcre -lm -lgc -lpthread -levent -lrt -ldl
thesseyren@x86_64:~/crystal$ file .build/crystal.o
.build/crystal.o: ELF 32-bit LSB relocatable, ARM, EABI5 version 1 (SYSV), with debug_info, not stripped

```

Cross-compile command printed and object file successfully generated.

Now the exact setup on `armv7l` device:

```auto
thesseyren@armv7l:~$ uname -a
Linux localhost 3.4.5-6164126 #1 SMP PREEMPT Mon Oct 17 15:39:25 KST 2016 armv7l armv7l armv7l GNU/Linux
thesseyren@armv7l:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.3 LTS
Release: 20.04
Codename: focal
thesseyren@armv7l:~$ llvm-config-12 --host-target
armv7l-unknown-linux-gnueabihf

```

Version list of required libraries on `armv7l`:

```auto
||/ Name Version Arch
+++-===================-============================-============-
ii automake 1:1.16.1-4ubuntu6 all         
ii build-essential 12.8ubuntu1.1 armhf       
ii libbsd-dev:armhf 0.10.0-1 armhf       
ii libedit-dev:armhf 3.1-20191231-1 armhf       
ii libevent-dev 2.1.11-stable-1 armhf       
ii libgc-dev:armhf 1:7.6.4-0.4ubuntu1 armhf       
ii libgc1c2:armhf 1:7.6.4-0.4ubuntu1 armhf       
ii libgmp-dev:armhf 2:6.2.0+dfsg-4 armhf       
ii libgmpxx4ldbl:armhf 2:6.2.0+dfsg-4 armhf       
ii libpcre3-dev:armhf 2:8.39-12build1 armhf       
ii libssl-dev:armhf 1.1.1f-1ubuntu2.9 armhf       
ii libtool 2.4.6-14 all         
ii libxml2-dev:armhf 2.9.10+dfsg-5ubuntu0.20.04.1 armhf       
ii libyaml-dev:armhf 0.2.2-1 armhf       
ii lld-12 1:12.0.0-3ubuntu1~20.04.4 armhf       
ii llvm-12 1:12.0.0-3ubuntu1~20.04.4 armhf       
ii llvm-12-dev 1:12.0.0-3ubuntu1~20.04.4 armhf       

```

I did these on `armv7l`:

```auto
thesseyren@armv7l:~$ sudo ln -sf /usr/bin/ld.lld-12 /usr/bin/ld.lld
thesseyren@armv7l:~$ git clone https://github.com/crystal-lang/crystal.git
thesseyren@armv7l:~$ cd crystal/
thesseyren@armv7l:~/crystal$ git checkout 1.2.2
thesseyren@armv7l:~/crystal$ mkdir .build
thesseyren@armv7l:~/crystal$ make deps
Using /usr/bin/llvm-config-12 [version=12.0.0]
g++ -c -o src/llvm/ext/llvm_ext.o src/llvm/ext/llvm_ext.cc -I/usr/lib/llvm-12/include -std=c++14 -fno-exceptions -D_GNU_SOURCE -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D __STDC_CONSTANT_MACROS -D__ STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
thesseyren@armv7l:~/crystal$ file src/llvm/ext/llvm_ext.o
src/llvm/ext/llvm_ext.o: ELF 32-bit LSB relocatable, ARM, EABI5 version 1 (SYSV), not stripped

```

And transferred program object file from `x86_64` to `armv7l`:

```auto
thesseyren@x86_64:~$ scp .build/crystal.o armv7l:crystal/.build

```

As final step, I run cross compile output:

```auto
thesseyren@armv7l:~/crystal$ cc .build/crystal.o -o .build/crystal -rdynamic -L/usr/bin/../lib/crystal src/llvm/ext/llvm_ext.o `"/usr/bin/llvm-config-12" --libs --system-libs --ldflags 2> /dev/null` -lstdc++ -lpcre -lm -lgc -lpthread -levent -lrt -ldl
/usr/bin/ld: .build/crystal.o: in function `__muloti4':
/home/thesseyren/Masaüstü/crystal-arm/crystal/src/crystal/compiler_rt/mul.cr:42: undefined reference to `__multi3'
/usr/bin/ld: .build/crystal.o: in function `//':
/home/thesseyren/Masaüstü/crystal-arm/crystal/src/int.cr:105: undefined reference to `__multi3'
/usr/bin/ld: /home/thesseyren/Masaüstü/crystal-arm/crystal/src/int.cr:105: undefined reference to `__multi3'
/usr/bin/ld: .build/crystal.o: in function `_carrying_mul':
/home/thesseyren/Masaüstü/crystal-arm/crystal/src/crystal/compiler_rt/divmod128.cr:45: undefined reference to `__multi3'
/usr/bin/ld: .build/crystal.o: in function `_carrying_mul_add':
/home/thesseyren/Masaüstü/crystal-arm/crystal/src/crystal/compiler_rt/divmod128.cr:56: undefined reference to `__multi3'
/usr/bin/ld: .build/crystal.o:/home/thesseyren/Masaüstü/crystal-arm/crystal/src/crystal/compiler_rt/divmod128.cr:161: more undefined references to `__multi3' follow
collect2: error: ld returned 1 exit status

```

What do you think? Is it because old linux kernel version, incompatible llvm version or maybe not recently updated `libgc` from ubuntu repositories?.. Please reply what do you think, thanks.

I tested this on a different `armv7l` device and I got the same result:

```auto
thesseyren@another-armv7l:~$ uname -a
Linux localhost 3.10.9-8842622 #1 SMP PREEMPT Thu Jul 28 07:22:59 KST 2016 armv7l armv7l armv7l GNU/Linux

```

I also tested this on a 64-bit `aarch64` device and it just worked! :

```auto
Linux localhost 4.14.117-perf-gbbfb2f0 #1 SMP PREEMPT Sun Oct 25 23:27:54 CST 2020 aarch64 Android

```

---

<div class="post-metadata">

**Author:** ![jgaskins](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/jgaskins/32/2449_2.png) [@jgaskins](https://forum.crystal-lang.org/u/jgaskins)\
**Post date:** [November 21, 2021, 10:59pm UTC](https://forum.crystal-lang.org/t/cant-compile-crystal-1-2-2-on-32-bit-arm-armv7l-device-undefined-reference-to-multi3/4077/2 "2021-11-21T22:59:39Z")

</div>

I thought 32-bit arch support was removed recently, but I can’t seem to find it in the release notes.

---

<div class="post-metadata">

**Author:** ![straight-shoota](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/straight-shoota/32/36_2.png) [@straight-shoota](https://forum.crystal-lang.org/u/straight-shoota)\
**Post date:** [November 22, 2021, 12:18pm UTC](https://forum.crystal-lang.org/t/cant-compile-crystal-1-2-2-on-32-bit-arm-armv7l-device-undefined-reference-to-multi3/4077/3 "2021-11-22T12:18:30Z")

</div>

32-bit arm architectures are expected to work (see [Platform Support - Crystal](https://crystal-lang.org/reference/platform_support.html#tier-2)). But we don’t run CI on those platforms, so apparently something broke there and we didn’t notice. The compiler process works fine, the linker is just complaining about a missing symbol.

The unresolved symbol points to a missing `compiler-rt` library. If you install that on the target machine, your program should link.

We probably should implement this method in Crystal to avoid the dependency on `compiler-rt`. We already do that for some other functions from that library.

---

<div class="post-metadata">

**Author:** ![erdnaxeli](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/erdnaxeli/32/1242_2.png) [@erdnaxeli](https://forum.crystal-lang.org/u/erdnaxeli)\
**Post date:** [November 25, 2021, 1:16pm UTC](https://forum.crystal-lang.org/t/cant-compile-crystal-1-2-2-on-32-bit-arm-armv7l-device-undefined-reference-to-multi3/4077/4 "2021-11-25T13:16:38Z")

</div>

I installed `compiler-rt` (which is provided by `llvm-dev` on debian) and still have the same issue.

---

<div class="post-metadata">

**Author:** ![erdnaxeli](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/erdnaxeli/32/1242_2.png) [@erdnaxeli](https://forum.crystal-lang.org/u/erdnaxeli)\
**Post date:** [November 25, 2021, 1:35pm UTC](https://forum.crystal-lang.org/t/cant-compile-crystal-1-2-2-on-32-bit-arm-armv7l-device-undefined-reference-to-multi3/4077/5 "2021-11-25T13:35:45Z")

</div>

Is there something to add to the `ld` command to link against `compiler-rt`?

---

<div class="post-metadata">

**Author:** ![straight-shoota](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/straight-shoota/32/36_2.png) [@straight-shoota](https://forum.crystal-lang.org/u/straight-shoota)\
**Post date:** [November 25, 2021, 1:50pm UTC](https://forum.crystal-lang.org/t/cant-compile-crystal-1-2-2-on-32-bit-arm-armv7l-device-undefined-reference-to-multi3/4077/6 "2021-11-25T13:50:46Z")

</div>

You can pass `--link-flags` to the build command.  
But this topic is about cross-compilation. For that you can just edit the linker command directly.

Is your use case the same as the OP? If not, please open a new topic.

---

<div class="post-metadata">

**Author:** ![erdnaxeli](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/erdnaxeli/32/1242_2.png) [@erdnaxeli](https://forum.crystal-lang.org/u/erdnaxeli)\
**Post date:** [November 25, 2021, 1:58pm UTC](https://forum.crystal-lang.org/t/cant-compile-crystal-1-2-2-on-32-bit-arm-armv7l-device-undefined-reference-to-multi3/4077/7 "2021-11-25T13:58:12Z")

</div>

Same use case, same error when running `cc` (not `ld`, sorry).

I installed `llvm-dev` which provides `compiler-rt` on debian bullseye, but I got the same error. I am wondering if I have to edit the `cc` command.

---

<div class="post-metadata">

**Author:** ![straight-shoota](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/straight-shoota/32/36_2.png) [@straight-shoota](https://forum.crystal-lang.org/u/straight-shoota)\
**Post date:** [November 25, 2021, 4:34pm UTC](https://forum.crystal-lang.org/t/cant-compile-crystal-1-2-2-on-32-bit-arm-armv7l-device-undefined-reference-to-multi3/4077/8 "2021-11-25T16:34:55Z")

</div>

The linker command in the OP already includes `-lrt`, so you shouldn’t need to do anything else.

However, I see that `__multi3` might not be available on 32-bit arm platforms. It’s used for 128-bit integer support.

Best bet is probably to use Crystal 1.1.1 for now.

---

<div class="post-metadata">

**Author:** ![straight-shoota](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/straight-shoota/32/36_2.png) [@straight-shoota](https://forum.crystal-lang.org/u/straight-shoota)\
**Post date:** [November 25, 2021, 8:20pm UTC](https://forum.crystal-lang.org/t/cant-compile-crystal-1-2-2-on-32-bit-arm-armv7l-device-undefined-reference-to-multi3/4077/9 "2021-11-25T20:20:07Z")

</div>

I filed a bug report here: [Can't build any programs on 32-bit ARM · Issue #11497 · crystal-lang/crystal · GitHub](https://github.com/crystal-lang/crystal/issues/11497)

This does not affect the compiler specifically, but every Crystal program. The issue includes a patch you can apply to your stdlib. Or go with 1.1.1