Unikernels are minimal single-purpose virtual machines. They are highly popular in the research domain due to the benefits they provide. A barrier to their widespread adoption is the difficulty/impossibility to port existing applications to current unikernels. HermiTux is the first unikernel providing system call-level binary compatibility with Linux applications. It is composed of a hypervisor and a lightweight kernel layer emulating the load- and runtime Linux ABI. HermiTux relieves application developers from the burden of porting software, while providing unikernel benefits such as security through hardware-assisted virtualized isolation, swift boot time, and low disk/memory footprint. Fast system calls and kernel modularity are enabled through binary rewriting and analysis techniques, as well as shared library substitution. HermiTuxs design principles are architecture-independent and we present a prototype on both the x86-64 and ARM aarch64 ISAs, targeting various cloud as well as edge/embedded deployments. We demonstrate HermiTuxs compatibility over a range of native C/C++/Fortran/Python Linux applications. We also show that it offers a similar degree of lightweightness compared to other unikernels, and that it performs similarly to Linux in many cases: its performance overhead averages 3% in memory- and compute-bound scenarios, and its I/O performance is acceptable.

Unikernels are minimal single-purpose virtual machines. They are highly popular in the research domain due to the benefits they provide. A barrier to their widespread adoption is the difficulty/impossibility to port existing applications to current unikernels. HermiTux is the first unikernel providing binary-compatibility with Linux applications. It is composed of a hypervisor and lightweight kernel layer emulating OS interfaces at load- and runtime in accordance with the Linux ABI. HermiTux relieves application developers from the burden of porting software, while providing unikernel benefits such as security through hardware-assisted virtualized isolation, swift boot time, and low disk/memory footprint. Fast system calls and kernel modularity are enabled through binary rewriting and analysis techniques, as well as shared library substitution. Compared to other unikernels, HermiTux boots faster and has a lower memory/disk footprint. We demonstrate that over a range of native C/C++/Fortran/Python Linux applications, HermiTux performs similarly to Linux in most cases: its performance overhead averages 3% in memory- and compute-bound scenarios.

The ability to quickly set up and tear down a virtual machine is critical for today's cloud elasticity, as well as in numerous other scenarios: guest migration/consolidation, event-driven invocation of micro-services, dynamically adaptive unikernel-based applications, micro-reboots for security or stability, etc.