elfconv: Bridging Linux Applications to WebAssembly Without Source Code

The emergence of elfconv represents a significant evolution in binary compatibility technology. This ahead-of-time translator directly converts Linux/ELF binaries into WebAssembly modules capable of running in both browser environments and WASI runtimes. By circumventing the need for source code access, elfconv addresses a fundamental limitation in software portability while demonstrating performance characteristics that challenge conventional wisdom about binary translation overhead.

The Source-Code Barrier

Traditional approaches to WebAssembly porting require complete source code access and per-language toolchain support, creating insurmountable barriers for legacy systems, proprietary software, and complex codebases with deprecated dependencies. Projects like v86 and container2wasm attempted workarounds through full CPU emulation, but incurred performance penalties exceeding 10× native execution. elfconv's architectural innovation lies in its layered approach:

1. Machine Code Translation: Leveraging modified components from Remill, elfconv disassembles AArch64 instructions (with x86-64 support in development) into LLVM intermediate representation
2. Syscall Virtualization: A runtime layer intercepts Linux system calls, translating them into WebAssembly-compatible operations
3. AOT Compilation: The translated IR compiles directly to optimized WebAssembly binaries

This methodology enables execution of unmodified Linux applications like GNU Bash in browser environments, even supporting experimental fork() and execve() operations previously considered impractical in WebAssembly's sandboxed execution model.

Performance Characteristics

Benchmark comparisons against Emscripten and WASI-SDK reveal surprising efficiency:

Benchmark	Environment	Native Wasm	elfconv	Relative Performance
Eratosthenes Sieve	Browser	0.567s	0.692s	82%
LINPACK	WASI	4821 MFLOPS	2720 MFLOPS	56%
MNIST Neural Net	Browser	2.138s	2.255s	96%

These results demonstrate 56-96% of native WebAssembly performance—orders of magnitude superior to emulation-based approaches. The variance stems from syscall translation overhead and incomplete instruction support, yet still establishes a viable performance baseline for non-emulated binary translation.

Practical Implications

Three transformative use cases emerge:

1. Legacy Application Preservation: Organizations can port proprietary or abandoned Linux software to web-executable formats without reverse engineering
2. Cross-Platform Library Distribution: Shared C/C++ libraries compiled for Linux become directly usable in WebAssembly projects
3. Educational Sandboxes: Operating system concepts requiring process forking become demonstrable in browser environments

The project acknowledges its experimental status—current limitations include AArch64 exclusivity, static linking requirements, and partial syscall coverage (approximately 40% implemented). Yet its open-source nature invites collaboration on critical pathways like x86-64 support and shared object integration.

Philosophical Considerations

elfconv challenges the assumption that WebAssembly requires source-level control. By treating binaries as transferable computation artifacts rather than locked implementations, it suggests a future where execution environments become interchangeable commodities. This approach carries inherent tensions: the abstraction layer necessarily obscures low-level behaviors, while syscall emulation creates maintenance challenges as Linux interfaces evolve.

For developers, the quickstart guide provides Docker-based tooling to experiment with conversion workflows. As the project evolves toward production readiness, its most profound contribution may be demonstrating that binary translation—long considered a high-overhead solution—can achieve viable performance through modern compilation techniques. This opens architectural possibilities beyond WebAssembly, potentially extending to other constrained execution environments where source availability remains problematic.