As described in Del 2.2, «Devices Requiring Firmware», some devices require firmware to be loaded. In most cases the device will not work at all if the firmware is not available; sometimes basic functionality is not impaired if it is missing and the firmware is only needed to enable additional features.
Starting with Debian GNU/Linux 12.0, following the 2022 General Resolution about non-free firmware, official installation images (like netinst) can include non-free firmware packages. Even with those firmware packages available, some firmware files might still be missing. Or one might be using netboot files, which don't include firmware packages.
If a device driver requests firmware that is not available,
debian-installer will display a dialog offering to load the missing firmware. If this option is selected,
debian-installer will scan available devices for either loose firmware files or packages containing firmware. If found, the firmware will be copied to the correct location (
/lib/firmware) and the driver module will be reloaded.
Which devices are scanned and which file systems are supported depends on the architecture, the installation method and the stage of the installation. Especially during the early stages of the installation, loading the firmware is most likely to succeed from a FAT-formatted USB stick. On i386 and amd64 firmware can also be loaded from an MMC or SD card.
Note that it is possible to skip loading the firmware if you know the device will also function without it, or if the device is not needed during the installation.
The most common method to load such firmware is from some removable medium such as a USB stick. To prepare a USB stick (or other medium like a hard drive partition), the firmware files or packages must be placed in either the root directory or a directory named
/firmware of the file system on the medium. The recommended file system to use is FAT as that is most certain to be supported during the early stages of the installation.
Tarballs and zip files containing current packages for the most common firmware, and the associated metadata to ensure a proper detection by the installer (
dep11 directory), are available from:
Just download the tarball or zip file for the correct release and unpack it to the file system on the medium.
It is also possible to copy individual firmware files to the medium. Loose firmware could be obtained for example from an already installed system or from a hardware vendor.
Any firmware loaded during the installation will be copied automatically to the installed system. In most cases this will ensure that the device that requires the firmware will also work correctly after the system is rebooted into the installed system. However, if the installed system runs a different kernel version than the installer, there is a slight chance that the firmware cannot be loaded due to version skew.
If the firmware was loaded from a firmware package,
debian-installer will also install this package for the installed system and will automatically add the non-free-firmware section of the package archive in APT's
sources.list. This has the advantage that the firmware should be updated automatically if a new version becomes available.
If loading the firmware was skipped during the installation, the relevant device will probably not work with the installed system until the firmware (package) is installed manually.
If the firmware was loaded from loose firmware files, the firmware copied to the installed system will not be automatically updated unless the corresponding firmware package (if available) is installed after the installation is completed.
Depending on how the installation was performed, it might be that the need for some firmware was not detected during installation, that the relevant firmware was not available, or that one chose not to install some firmware at that time. In some cases, a successful installation can still end up in a black screen or a garbled display when rebooting into the installed system. When that happens, the following workarounds can be tried:
nomodeset option on the kernel command line. This might help boot into a «fallback graphics» mode.
Use the Ctrl+Alt+F2 key combination to switch to VT2, which might offer a functional login prompt.