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thenewwazoo and rbradford Base MemoryRegion IO methods on a generic impl
This commit slightly refactors `MemoryRegion::read_*` and
`MemoryRegion::write_*` methods (and corresponding IO methods) to rely
on (private) `MemoryRegion::read<T>/write<T>` methods.

This does not alter any calls to the explicitly-notated reader and
writer methods, even if type inference would otherwise make a call to
`read` or `write` possible.

Signed-off-by: Brandon Matthews <>
Latest commit bbcb868 May 10, 2019

Simple KVM firmware

This project is an experiment and should not be used production workloads.

This repository contains a simple KVM firmware that is designed to be launched from anything that supports loading ELF binaries and running them with the Linux kernel loading standard.

The ultimate goal is to be able to use this "firmware" to be able to load a bootloader from within a disk image.

Currently it will directly load a kernel from a disk image that follows the Boot Loader Specification

Although this project has been developed using Firecracker as it does not currently support resetting the virtio block device it is not possible to boot all the way into the OS.


To compile:

cargo xbuild --release --target target.json

The result will be in:


Debug builds do not currently function.


  • virtio (MMIO & PCI) block support
  • GPT parsing (to find EFI system partition)
  • FAT12/16/32 directory traversal and file reading
  • bzImage loader
  • "Boot Loader Specification" parser


Works with Firecracker as a drop in replacement for the Linux kernel. It does not work with crosvm as crosvm has a hardcoded kernel function start address.


As per quick start

Replacing the kernel and rootfs to point at the firmware and the full disk image instead.

curl --unix-socket /tmp/firecracker.socket -i \
    -X PUT 'http://localhost/boot-source'   \
    -H 'Accept: application/json'           \
    -H 'Content-Type: application/json'     \
    -d '{
        "kernel_image_path": "target/target/release/hypervisor-fw",
        "boot_args": ""

curl --unix-socket /tmp/firecracker.socket -i \
    -X PUT 'http://localhost/drives/rootfs' \
    -H 'Accept: application/json'           \
    -H 'Content-Type: application/json'     \
    -d '{
        "drive_id": "rootfs",
        "path_on_host": "clear-28660-kvm.img",
        "is_root_device": true,
        "is_read_only": false

curl --unix-socket /tmp/firecracker.socket -i \
    -X PUT 'http://localhost/actions'       \
    -H  'Accept: application/json'          \
    -H  'Content-Type: application/json'    \
    -d '{
        "action_type": "InstanceStart"

Currently Firecracker's virtio block device does not support resetting the device and as such it is not possible for the booted Linux kernel to take over the device from the firmware.


"cargo test" needs disk images from

And clear-28660-kvm.img:

sha1sum: 5fc086643dea4b20c59a795a262e0d2400fab15f


  • PE32 loader
  • EFI runtime services required for booting


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