rdma-core-mummy

rdma-core-mummy is a lightweight wrapper library that provides stable static linking capabilities for RDMA (Remote Direct Memory Access) applications while maintaining runtime compatibility with different OFED versions.

Overview

When building RDMA applications, directly linking against rdma-core libraries can lead to compatibility issues due to varying IBVERBS_PRIVATE_@IBVERBS_PABI_VERSION@ between different OFED versions. While rdma-core provides static build options, it requires bundling the entire rdma-core source code, which can be cumbersome.

Furthermore, many Linux distributions do not provide static libraries (*.a) in their rdma-core packages. For example:

• RHEL/CentOS splits RDMA into runtime and development packages, but still only provides dynamic libraries
• Even when installing OFED, static libraries are not included by default

This makes it challenging to create statically linked RDMA applications, especially when portability across different systems is required.

rdma-core-mummy solves these issues by:

• Providing a minimal static library that contains only the necessary symbols
• Dynamically loading the actual RDMA functions at runtime
• Maintaining binary portability across different OFED versions
• Eliminating the need for distribution-provided static libraries

Features

• Static linking support for:
  • libibverbs (InfiniBand verbs)
  • librdmacm (RDMA Connection Manager)
  • libibumad (InfiniBand User MAD)
• Runtime dynamic loading of RDMA functions
• No dependency on specific IBVERBS_PRIVATE versions
• Lightweight alternative to full rdma-core static linking
• Works on distributions without static RDMA libraries

Requirements

• CMake 3.7 or later
• C compiler with C99 support
• OFED or rdma-core development environment

Building

mkdir build
cd build
cmake ..
make

Optional: Build with examples

cmake -DBUILD_EXAMPLES=ON ..
make

Usage

In CMake Projects

Add rdma-core-mummy to your project:

add_subdirectory(path/to/rdma-core-mummy)
target_link_libraries(your_target
    PRIVATE
        ibverbs    # For InfiniBand verbs
        rdmacm     # For RDMA Connection Manager
        ibumad     # For InfiniBand User MAD
)

In Your Code

Just include the necessary headers and use RDMA functions normally:

#include <infiniband/verbs.h>
#include <rdma/rdma_cma.h>

int main() {
    // Your RDMA code here
    struct ibv_device **dev_list;
    int num_devices;
    
    dev_list = ibv_get_device_list(&num_devices);
    // ...
    
    return 0;
}

How It Works

rdma-core-mummy uses function pointers and dlopen to dynamically load RDMA functions at runtime from the system's installed RDMA libraries. This approach:

• Provides stable symbols for static linking
• Loads actual implementations from the system's RDMA libraries at runtime
• Maintains compatibility across different OFED versions

Limitations

• Requires the presence of RDMA libraries (libibverbs.so.1, etc.) at runtime
• Does not provide complete rdma-core functionality - only commonly used functions
• Not suitable for environments where dynamic loading is not allowed

Contributing

Contributions are welcome! Please feel free to submit pull requests with:

• Additional function wrappers
• Bug fixes
• Documentation improvements
• Example code