Linux firmware is a package distributed alongside the Linux kernel that contains firmware binary blobs necessary for partial or full functionality of certain hardware devices. These binary blobs are usually proprietary because some hardware manufacturers do not release source code necessary to build the firmware itself.
Starting at Broxton (a Skylake-based micro-architecture) Intel CPUs require binary blobs for additional low-power idle states (DMC), graphics workload scheduling on the various graphics parallel engines (GuC), and offloading some media functions from the CPU to GPU (HuC).
For security reasons, hotloading firmware into a running kernel has been shunned upon. Modern init systems such as systemd have strongly discouraged loading firmware from userspace.
A few kernel options are important to consider when building in firmware support for certain devices in the Linux kernel:
Including firmware files into binary kernel images that are not available under the terms of the GPL, may result in a violation of the GPL if the image is distributed. It is wise to consult a lawyer before distributing images that contain firmware files from sys-kernel/linux-firmware.
Kernels prior to v4.18
For kernels released prior to version 4.18:
- CONFIG_FIRMWARE_IN_KERNEL (DEPRECATED)
- Note this option has been removed as of versions v4.16 and above. Enabling this option was previously necessary to build each required firmware blob specified by EXTRA_FIRMWARE into the kernel directly, where the
request_firmware()function will find them without having to make a call out to userspace. On older kernels, it is necessary to enable it.
Device Drivers ---> Generic Driver Options ---> -*- Userspace firmware loading support [*] Include in-kernel firmware blobs in kernel binary (/lib/firmware) Firmware blobs root directory
Kernels v4.18 and higher
For kernels beginning with 4.18:
- Firmware loading facility ( CONFIG_FW_LOADER )
- This option is provided for the case where none of the in-tree modules require userspace firmware loading support, but a module built out-of-tree does.
- Build named firmware blobs into the kernel binary ( CONFIG_EXTRA_FIRMWARE )
- This option is a string and takes the (space-separated) names of firmware files to be built into the kernel. These files will then be accessible to the kernel at runtime.
Device Drivers ---> Generic Driver Options ---> Firmware loader ---> -*- Firmware loading facility () Build named firmware blobs into the kernel binary (/lib/firmware) Firmware blobs root directory
USE flags for sys-kernel/linux-firmware Linux firmware files
emerge --ask sys-kernel/linux-firmware
After emerging sys-kernel/linux-firmware, the configuration file is made into /etc/portage/savedconfig/sys-kernel/linux-firmware-ddmmyyyy. This file can be edited and the unwanted lines be commented out or deleted. Edit and save the file and re-emerge sys-kernel/linux-firmware with the
savedconfig USE flag:
echo sys-kernel/linux-firmware savedconfig >> /etc/portage/package.use/kernel
emerge --ask sys-kernel/linux-firmware
Firmware to be loaded into the kernel can be compressed in order to achieve greater space efficiency and faster read speeds (at the expense of processing time). See the CONFIG_FW_LOADER_COMPRESS kernel symbol for additional information.
xz compression is supported via the CONFIG_FW_LOADER_COMPRESS_XZ symbol. Note that only none or crc32 integrity check types (by passing
-C crc32 option to the xz command) are supported.
Searching for loaded firmware
dmesg can be grepped to determine what firmware has been loaded:
dmesg | grep -i firmware
emerge --ask --depclean --verbose sys-kernel/linux-firmware
- Fwupd — a daemon that provides a safe, reliable way of applying firmware updates on Linux.
- Kernel — the core of the operating system.
- Iwlwifi — the wireless driver for Intel's current wireless chips.
- Microcode — describes various ways to update a CPU's microcode in Gentoo.
- AMDGPU — the next generation family of open source graphics drivers using the new Display Core (DC) framework for Vega GPUs and Raven Ridge APUs. It is however also capable of handling newer AMD/ATI Radeon graphics cards based on GCN1.0+, namely the Southern Islands, Sea Islands, Volcanic Islands, and Arctic Islands chipsets.
- Intel — the open source graphics driver for Intel GMA on-board graphics cards, starting with the Intel 810.