报错问题：
CXX/LD -o .build_release/tools/convert_imageset.bin
.build_release/lib/libcaffe.so: undefined reference to google::protobuf::io::CodedOutputStream::WriteVarint64ToArray(unsigned long long, unsigned char*)' .build_release/lib/libcaffe.so: undefined reference togoogle::protobuf::internal::WireFormatLite::WriteInt64(int, long long, google::protobuf::io::CodedOutputStream*)’
.build_release/lib/libcaffe.so: undefined reference to google::protobuf::UnknownFieldSet::AddVarint(int, unsigned long long)' .build_release/lib/libcaffe.so: undefined reference togoogle::protobuf::io::CodedOutputStream::VarintSize64(unsigned long long)’
.build_release/lib/libcaffe.so: undefined reference to `google::protobuf::io::CodedOutputStream::WriteVarint64(unsigned long long)’
collect2: error: ld returned 1 exit status
make: *** [.build_release/tools/convert_imageset.bin] Error 1

解决方案：

[UPDATED, DO NOT TRY THIS]Please try to remove the os versions of protobuf in /usr/lib/x86_64-linux-gnu. (Something like libprotobuf., libprotobuf-lite., libprotoc.*). There are two versions of protobuf will cause conflicts when compiling.
Then try to install newest version of protobuf.