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#59 in Operating systems

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uhyve - A minimal hypervisor for RustyHermit

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uhyve is small hypervisor to boot the library operating systems RustyHermit, which is a unikernel operating system targeting a scalable and predictable runtime behavior for HPC and cloud environments.


It is required to install the nightly version of the Rust toolchain on your Linux system. Please visit the Rust website and follow the installation instructions.


The final step is to create a copy of the repository and to build the kernel:

$ # Get our source code.
$ git clone git@github.com:hermitcore/uhyve.git
$ cd uhyve

$ # Get a copy of the Rust source code so we can rebuild core
$ # for a bare-metal target.
$ cargo build

Use the hypervisor to start the unikernel.

$ ./uhyve /path_to_the_unikernel/hello_world

There are two environment variables to modify the virtual machine: The variable HERMIT_CPUS specifies the number of cores the virtual machine may use. The variable HERMIT_MEM defines the memory size of the virtual machine. The suffixes M and G can be used to specify a value in megabytes or gigabytes, respectively. By default, the loader initializes a system with one core and 512 MiB RAM. For instance, the following command starts the demo application in a virtual machine, which has 4 cores and 8GiB memory:

$ HERMIT_CPUS=4 HERMIT_MEM=8G uhyve /path_to_the_unikernel/hello_world

Setting the environment variable HERMIT_VERBOSE to 1 makes the hypervisor print kernel log messages to the terminal.

$ HERMIT_VERBOSE=1 uhyve /path_to_the_unikernel/hello_world


Licensed under either of

at your option.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.


~158K SLoC