Linux firmware

Linux firmware [[Article description::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.

Modern graphics cards from AMD and NVIDIA almost certainly require binary blobs to be loaded for the hardware to operate correctly.

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).[1]

Additionally, modern Intel Wi-Fi chipsets almost always require blobs.[2]

Installation

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.

Kernel

A few kernel options are important to consider when building in firmware support for certain devices in the Linux kernel:

Warning
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.

For kernels before 4.18:

CONFIG_FIRMWARE_IN_KERNEL (DEPRECATED)
Note this option has been removed as of versions v4.16 and above.[3] 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.
KERNEL Enable support for Linux firmware
Device Drivers  --->
  Generic Driver Options  --->
    -*- Userspace firmware loading support
    [*]   Include in-kernel firmware blobs in kernel binary
    (/lib/firmware) Firmware blobs root directory

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
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.
KERNEL Enable support for Linux firmware
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

USE flags for sys-kernel/linux-firmware Linux firmware files

initramfs Create and install initramfs for early microcode loading in /boot (only AMD for now)
redistributable Install also non-free (but redistributable) firmware files
savedconfig Allows individual selection of firmware files
unknown-license Install firmware files whose license is unknown
Data provided by the Gentoo Package Database · Last update: 2021-03-17 22:38 More information about USE flags

Emerge

root #emerge --ask sys-kernel/linux-firmware

Optional: Savedconfig

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:

root #echo sys-kernel/linux-firmware savedconfig >> /etc/portage/package.use/kernel
root #emerge --ask sys-kernel/linux-firmware

Troubleshooting

Searching for loaded firmware

dmesg can be grepped to determine what firmware has been loaded:

user $dmesg | grep -i firmware

Removal

Unmerge

root #emerge --ask --depclean --verbose sys-kernel/linux-firmware

See also

  • 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 how 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.

External resources

References

  1. ↑ https://01.org/linuxgraphics/downloads/firmware
  2. ↑ https://wireless.wiki.kernel.org/en/users/drivers/iwlwifi
  3. ↑ https://github.com/torvalds/linux/commit/7f55c733b6607d6bfc16057641f18280e587cca
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