vmx86

vmx86 is an x86_64 interpreter built on top of the GraalVM.

Build Dependencies

• gcc for libmemory (high performance memory library) and libemu86 (ptrace based debugging tool)
• Linux/x86_64 host with gcc to build the test cases

It is possible to build vmx86 on any non-Linux/x86_64 host as long as mx and a JDK are available. However, such configurations are not tested. If vmx86 is built on any host other than Linux/x86_64, the test programs have to be cross-compiled or copied from a Linux/x86_64 host. It might be necessary to change the suite.py in order to do that.

How to get started

Create a new directory, e.g. git which will contain all necessary git repositories:

mkdir git && cd git

Install mx which is used to build vmx86:

git clone https://github.com/graalvm/mx
export PATH=$PWD/mx:$PATH

Clone the Graal repository as well as this repository:

git clone https://github.com/oracle/graal
git clone https://github.com/graalvm/vmx86

Note: the current implementation of vmx86's NFI is incompatible with the current version of Graal. Use Graal commit 07bc60dbd6b15073c9c0669e1638855666048915 to avoid this problem.

Set JAVA_HOME to a JDK >= 1.8, e.g.:

echo JAVA_HOME=/usr/lib/jvm/java-11-openjdk > vmx86/mx.vmx86/env

Note: To avoid unnecessary trouble, use OpenJDK 11.

Build vmx86:

cd vmx86 && mx build

Running a program

To run a program, start it with mx vmx86:

mx vmx86 /bin/uname -a

Running on Graal

In order to use Graal as a JIT compiler, first build Graal:

mx --dynamicimport /compiler build

Then:

mx --dynamicimport /compiler --jdk jvmci vmx86 /bin/uname -a

IDE Setup

Generate Eclipse project files:

mx eclipseinit

Generate IntelliJ project files:

mx intellijinit

Execution Traces

First, record an execution trace:

mx tvmx86 /bin/echo hello

This creates a trace file called trace.trc in the current working directory. Then, inspect it in trcview:

mx trcview

Debugging the Interpreter

To check if all CPU instructions are implemented correctly (at least for a given program execution), one can also verify an execution trace on the host CPU (as long as the host has an x86_64 CPU):

mx trchk trace.trc

Project name?

Basically "VM" as in "Virtual Machine" + "x86" like the architecture name. Or "vmx" like the virtualization extension feature flag in /proc/cpuinfo + "86". Who knows.