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This application is designed to modify the EFI partition and bootloader of your system. Users acknowledge that running this program can result in corruption of the operating system and loss of data.


The mitigations for Spectre require updates to both operating system kernels and processor microcode. While microcode updates can be deployed at runtime, not all operating system vendors are redistributing processor microcode updates, instead relying on hardware manufactures to supply it through updated platform firmware. However, millions of system are no longer receiving manufacturer support, and so have no means to apply the processor microcode patches, leaving them unable to mitigate the Spectre vulnerabilities.

MicroRenovator provides a mechanism for deploying processor microcode that is independent of both manufacturer and operating-system supplied updates, by adding a custom EFI boot script which loads microcode prior to the operating system being run. This enables the operating system kernel to detect the updated microcode and enable Spectre mitigations that depend on it.


Boot the target system using a linux LiveCD or USB, such as Fedora or Ubuntu

Clone this repository

git clone

Then run to install the microcode updater


The installer will perform the following actions:

  1. find appropriate microcode for the current system
  2. attempt to locate an EFI partition
  3. find the bootloader on that partition
  4. copy the included microcode updater to the EFI partition
  5. add a startup script to run the microcode updater prior to the OS bootloader

To uninstall, run

./ -u

Offline Usage

The kickstart file can be used to build a custom LiveCD image based on Fedora 27 that includes all the necessary files and packages to build and install the microcode loader application.

Install the LiveCD Creator utility and the sample kickstart files, and make a local copy of the kickstart files to work with.

dnf -y install livecd-tools spin-kickstarts
cp /usr/share/spin-kickstarts/\*.ks .

The LiveCD utility will need to be modified to launch the correct OS on boot.

sed -i 's/set default="1"/set default="0"/' /usr/lib/python3.6/site-packages/imgcreate/

Finally, run LiveCD-Creator to build the ISO

livecd-creator --verbose --config=reno-live.ks --fslabel=URENO

The resulting URENO.iso file is a bootable image that can be burned to a DVD or USB drive like any other live image. Once booted into this live image, simply run the installer script.

Building EFI Utilities

Building the EFI applications requires an EDK2 environment.

Copy the Uload directory into the edk2/ folder of a configured EDK2 environment, and run the following:

build -a X64 -p ShellPkg/ShellPkg.dsc -b RELEASE
build -a X64 -p Uload/Uload.dsc -b RELEASE

To use the resulting files instead of the provided .efi binaries, change the "edk2_dir" in to point at the desired edk2/ directory.

If using a LiveCD created by the MicroRenovator kickstart file, running the included script will generate the necessary files.

Known Issues

  • Not compatible with Sleep (S3). Hibernate is not impacted
  • Not currently compatible with UEFI secure boot
  • Windows sometimes fails to boot after running Uload.efi, rebooting usually resolves the problem


  • error handling in EFI application and script
  • re-implement as DXE driver (to support S3)


Pre-OS microcode updater




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