UEFI firmware capsules for Linux

This project provides the pieces needed to flash an industry standard UEFI capsule in a Linux OS. It also aims to be compatible with some implementation decisions that were made in Windows.

The following binaries are produced:

• libfwup library providing APIs to do UEFI updates for other applications
• fwupdate reference command line tool
• fwup.efi EFI application used for flashing the update from EFI.

fwupd

fwupd is a project for managing firmware updates of many types of devices. It has supported UEFI firmware update ever since its first release. fwupd versions 1.0.x and earlier use libfwupd from this project for performing the flash (following most of Normal Flow below).

fwupd versions 1.1.x and later have merged the code from this project directly into the codebase and will manage boot assets directly at installation time. This project is not needed when using a newer fwupd.

Normal flow

UEFI capsule updates are not actually flashed within Linux. They're staged for update to be installed on the next boot.

1. fwupdate --apply will be executed with the capsule payload as an argument
2. libfwup will copy the payload to the EFI system partition.
3. libfwup will create EFI NVRAM entries pointing to the correct payload on the EFI system partition.
4. libfwup will create a new EFI Boot entry to launch the firmware updating EFI application.
5. libfwup will set the BootNext variable to run that application on next boot.
6. The user will reboot the system.
7. The fwup.efi application will examine EFI NVRAM entries to find capsules previously staged.
8. The fwup.efi application will call the BIOS UpdateCapsule() method to flash the capsules.
9. The BIOS will flash the capsules and then reboot back into the OS.

Usage

UEFI capsule updates are typically distributed by services such as LVFS in .CAB format. The command line tool provided by this project works directly on the payload stored in the .CAB. Most users should apply UEFI capsule updates with a higher level tool such as fwupd.

Dependencies

The following dependencies are needed to compile:

• libpopt
• efivar (>=33)
• gnu-efi (>= 3.0.2)
• elfutils

Optionally if libsmbios is present some additional features on Dell systems can be enabled as well.

Compiling

Optionally set the EFI system partition mount point. If not configured it will default to /boot/efi

# git config fwupdate.espmountdir $DIRECTORY

Set the EFI subdirectory directory that EFI binaries are installed into.

# git config fwupdate.efidir $DIRECTORY

This usually refers to the OS distributor. If not configured it will default to the value defined for ID in /etc/os-release or /usr/lib/os-release.

Run the build command

# make

Run the install command

# make install

Other notes

Some distributions don't use the same paths for the dependencies as in Make.defaults. For example on Debian and Ubuntu you need to override GNUEFIDIR to the correct path.

Command line

Checking if UEFI capsule updates are supported:

# fwupdate --supported

Checking which ESRT GUIDs are on the system:

# fwupdate --list

Display details of all ESRT entries:

# fwupdate --info

Applying a payload:

# fwupdate --apply=<guid> <payload>

Enable firmware updates on supported Dell systems (if compiled with libsmbios):

# fwupdate --enable