Unity: How to build grpc_csharp_ext for Magic Leap (and any other platforms)

[ryok...@gmail.com]

I'm trying to make streaming speech recognition (Google.Cloud.Speech.V1) work in Magic Leap app.

I've managed to make it work in Unity Editor (Windows x64) as in this video: 

https://twitter.com/ryoichirooka/status/1110313722826784768

But once I build it straight into Magic Leap runtime, I'll get this error:

grpc_csharp_ext.dll not found

... since this DLL in the project is built for Windows x64 runtime (which I just copied & pasted from repo) which works in Editor but won't get carried to Magic Leap runtime.

So I'm trying to build "grpc_csharp_ext.dll" for Magic Leap myself. And I'm stuck :)

Magic Leap has its own Linux OS called LuminOS, which has its own C/C++ builder called "Mabu".

More info (you may need to log in or something): https://creator.magicleap.com/learn/guides/sdk-mabu-ug-build-a-sample-mabu-project

Build files (.mabu) in Mabu look like this:

KIND = shared
OUTNAME = grpc_csharp_ext
SRCS = ../ext/grpc_csharp_ext.c
INCS = ../../../include

Above I'm basically telling Mabu to build a shared library (DLL) named as "grpc_csharp_ext", using the source C file and any files in the include folder for references.

Following is the log when Mabu runs the build file:

D:\Projects\_extern_\grpc\src\csharp\experimental>mabu grpc_csharp_ext.mabu -t release_win_msvc-2017_x64
[grpc_csharp_ext] Compiling grpc_csharp_ext.c...
grpc_csharp_ext.c
[grpc_csharp_ext] Linking DLL grpc_csharp_ext.dll...
   Creating library grpc_csharp_ext.lib and object grpc_csharp_ext.exp
grpc_csharp_ext.c-99b723c0f96300a2.o : error LNK2019: unresolved external symbol grpc_raw_byte_buffer_create referenced in function string_to_byte_buffer
grpc_csharp_ext.c-99b723c0f96300a2.o : error LNK2019: unresolved external symbol grpc_byte_buffer_length referenced in function grpcsharp_batch_context_recv_message_length
***** BUNCH OF OTHER LINK ISSUES *****
grpc_csharp_ext.c-99b723c0f96300a2.o : error LNK2019: unresolved external symbol gpr_thd_currentid referenced in function grpcsharp_log_handler
grpc_csharp_ext.dll : fatal error LNK1120: 67 unresolved externals
make: *** [D:/Projects/_extern_/grpc/src/csharp/experimental/.out/release_win_msvc-2017_x64/grpc_csharp_ext.mk:22: D:/Projects/_extern_/grpc/src/csharp/experimental/.out/release_win_msvc-2017_x64/grpc_csharp_ext.dll] Error

Note "unresolved external symbol" errors.

I'm thinking the cause is that those .h files in the include folder don't have actual implementation .c files.

For example, grpc/impl/codegen/byte_buffer.h goes like:

#ifndef GRPC_IMPL_CODEGEN_BYTE_BUFFER_H
#define GRPC_IMPL_CODEGEN_BYTE_BUFFER_H

#include <grpc/impl/codegen/port_platform.h>

#include <grpc/impl/codegen/grpc_types.h>

#ifdef __cplusplus
extern "C" {
#endif

/** Returns a RAW byte buffer instance over the given slices (up to \a nslices).
 *
 * Increases the reference count for all \a slices processed. The user is
 * responsible for invoking grpc_byte_buffer_destroy on the returned instance.*/
GRPCAPI grpc_byte_buffer* grpc_raw_byte_buffer_create(grpc_slice* slices,
                                                      size_t nslices);

/** Returns a *compressed* RAW byte buffer instance over the given slices (up to
 * \a nslices). The \a compression argument defines the compression algorithm
 * used to generate the data in \a slices.
 *
 * Increases the reference count for all \a slices processed. The user is
 * responsible for invoking grpc_byte_buffer_destroy on the returned instance.*/
GRPCAPI grpc_byte_buffer* grpc_raw_compressed_byte_buffer_create(
    grpc_slice* slices, size_t nslices, grpc_compression_algorithm compression);

which defines grpc_raw_byte_buffer_create() but doesn't implement it, hense the "unresolved symbol" error above (1st one).

I couldn't find those implementation .c files anywhere in the repo (except PHP ones).

I did read iOS/Android build files in Unity experimental folder in the repo, but failed to track down where the .c files are coming from.

So I'm stuck here.

• Can someone explain where all the other builds (cmakes) are fetching the implementation .c files from?
• Or does it actually need to be implemented anew for LuminOS?

Thank you!

Ryo

How can

.com/ryoichirooka/status/1110313722826784768

[ryok...@gmail.com]

Self-updating...

I've managed a little forward and done following:

- Generate a cmake toolchain (using Magic Leap SDK v0.20.0: https://creator.magicleap.com/learn/guides/sdk-mabu-ref-build-and-link-libraries#build-libraries-with-cmake)

- Run cmake (which succeeds) with a bash script as following:

rmdir build
mkdir -p build
cd build

cmake ../.. \
    -DCMAKE_BUILD_TYPE=Release \
    -DCMAKE_TOOLCHAIN_FILE=../magicleap.toolchain.cmake \
    -DRUN_HAVE_POSIX_REGEX=0 \
    -DRUN_HAVE_STD_REGEX=0 \
    -DRUN_HAVE_STEADY_CLOCK=0 \

Now I'm attempting to build the "grpc_csharp_ext" library as in:

make grpc_csharp_ext

which fails, with error output as following:

...
[ 31%] Generating sha1-armv8.S
[ 31%] Generating sha256-armv8.S
Scanning dependencies of target fipsmodule
[ 31%] Building C object third_party/boringssl/crypto/fipsmodule/CMakeFiles/fipsmodule.dir/bcm.c.o
[ 31%] Building C object third_party/boringssl/crypto/fipsmodule/CMakeFiles/fipsmodule.dir/is_fips.c.o
[ 31%] Building ASM object third_party/boringssl/crypto/fipsmodule/CMakeFiles/fipsmodule.dir/aesv8-armx.S.o
/Users/ryoichirooka/projects/grpc/cmake/build/third_party/boringssl/crypto/fipsmodule/aesv8-armx.S:37:2: error: instruction requires: neon
 eor v0.16b,v0.16b,v0.16b
 ^
/Users/ryoichirooka/projects/grpc/cmake/build/third_party/boringssl/crypto/fipsmodule/aesv8-armx.S:38:2: error: instruction requires: neon
 ld1 {v3.16b},[x0],#16
 ^
/Users/ryoichirooka/projects/grpc/cmake/build/third_party/boringssl/crypto/fipsmodule/aesv8-armx.S:40:2: error: instruction requires: neon
 ld1 {v1.4s,v2.4s},[x3],#32
 ^
...

Note "error: instruction requires: neon".

I haven't figured out how to address this one and am actively looking for solution. Please let me know if you have any directions

Thank you,

Ryo

[Jan Tattermusch]

I have no experience with MagicLeap, but from your description it looks like you're trying to do the right thing - basically you need to custom-build a version of grpc_csharp_ext  that targets LuminOS (and your steps to achieving so seem to be correct).

The build error with boringssl could be because it tries to build the assembly-optimized version of boringssl (see e.g. https://github.com/grpc/grpc/blob/master/doc/ssl-performance.md) and for some reason it fails.

You can try to disable the asm-optimized build by setting -DOPENSSL_NO_ASM=ON while invoking cmake (see FTR https://github.com/grpc/grpc/blob/f10596f0f3d6ab2dfe67b86d259a8d3effb73a99/cmake/ssl.cmake#L26),

and maybe that will unblock your build.