Linux firmware

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.

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 (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
 # Optional: Enable compressed firmware support
 [*] Enable compressed firmware support
 [*] Enable XZ-compressed firmware support
 [*] Enable ZSTD-compressed firmware support

USE flags

Emerge

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:

Optional: Compression

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.

sys-kernel/linux-firmware supports either xz or zstd (starting from Linux kernel 5.19^[3] ) compression via appropriate USE-flags. The kernel configuration should include CONFIG_FW_LOADER_COMPRESS_XZ and/or CONFIG_FW_LOADER_COMPRESS_ZSTD options to support these compression formats.

Troubleshooting

Searching for loaded firmware

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

This requires the use of Gentoo kernel (i.e. not a vanilla kernel) with CONFIG_GENTOO_PRINT_FIRMWARE_INFO=y set in the kernel configuration.

Removal

Unmerge

See also

• Fwupd — a daemon that provides a safe, reliable way of applying firmware updates on Linux.
• Kernel — a central part of the Gentoo operating system (OS)
• Iwlwifi — the wireless driver for Intel's current wireless chips.
• Microcode — describes various ways to update a CPU's microcode in Gentoo.
• AMDGPU — the open source graphics drivers for AMD Radeon and other GPUs.
• Intel — the open source graphics driver for Intel GMA on-board graphics cards and Intel iGPU and Intel Arc dedicated graphics cards, starting with the Intel 810.

External resources

• bug #732852

References

• Firmware
• Kernel