# SPDX-License-Identifier: GPL-2.0menu "Firmware loader" config FW_LOADER	tristate "Firmware loading facility" if EXPERT	select CRYPTO_LIB_SHA256 if FW_LOADER_DEBUG	default y	help	  This enables the firmware loading facility in the kernel. The kernel	  will first look for built-in firmware, if it has any. Next, it will	  look for the requested firmware in a series of filesystem paths: 		o firmware_class path module parameter or kernel boot param		o /lib/firmware/updates/UTS_RELEASE		o /lib/firmware/updates		o /lib/firmware/UTS_RELEASE		o /lib/firmware 	  Enabling this feature only increases your kernel image by about	  828 bytes, enable this option unless you are certain you don't	  need firmware. 	  You typically want this built-in (=y) but you can also enable this	  as a module, in which case the firmware_class module will be built.	  You also want to be sure to enable this built-in if you are going to	  enable built-in firmware (CONFIG_EXTRA_FIRMWARE). config FW_LOADER_DEBUG	bool "Log filenames and checksums for loaded firmware"	depends on DYNAMIC_DEBUG	depends on FW_LOADER	default FW_LOADER	help	  Select this option to use dynamic debug to log firmware filenames and	  SHA256 checksums to the kernel log for each firmware file that is	  loaded. config RUST_FW_LOADER_ABSTRACTIONS	bool "Rust Firmware Loader abstractions"	depends on RUST	select FW_LOADER	help	  This enables the Rust abstractions for the firmware loader API. if FW_LOADER config FW_LOADER_PAGED_BUF	bool config FW_LOADER_SYSFS	bool config EXTRA_FIRMWARE	string "Build named firmware blobs into the kernel binary"	help	  Device drivers which require firmware can typically deal with	  having the kernel load firmware from the various supported	  /lib/firmware/ paths. This option enables you to build into the	  kernel firmware files. Built-in firmware searches are preceded	  over firmware lookups using your filesystem over the supported	  /lib/firmware paths documented on CONFIG_FW_LOADER. 	  This may be useful for testing or if the firmware is required early on	  in boot and cannot rely on the firmware being placed in an initrd or	  initramfs. 	  This option is a string and takes the (space-separated) names of the	  firmware files -- the same names that appear in MODULE_FIRMWARE()	  and request_firmware() in the source. These files should exist under	  the directory specified by the EXTRA_FIRMWARE_DIR option, which is	  /lib/firmware by default. 	  For example, you might set CONFIG_EXTRA_FIRMWARE="usb8388.bin", copy	  the usb8388.bin file into /lib/firmware, and build the kernel. Then	  any request_firmware("usb8388.bin") will be satisfied internally	  inside the kernel without ever looking at your filesystem at runtime. 	  WARNING: If you include additional firmware files into your binary	  kernel image that are not available under the terms of the GPL,	  then it may be a violation of the GPL to distribute the resulting	  image since it combines both GPL and non-GPL work. You should	  consult a lawyer of your own before distributing such an image. 	  NOTE: Compressed files are not supported in EXTRA_FIRMWARE. config EXTRA_FIRMWARE_DIR	string "Firmware blobs root directory"	depends on EXTRA_FIRMWARE != ""	default "/lib/firmware"	help	  This option controls the directory in which the kernel build system	  looks for the firmware files listed in the EXTRA_FIRMWARE option. config FW_LOADER_USER_HELPER	bool "Enable the firmware sysfs fallback mechanism"	select FW_LOADER_SYSFS	select FW_LOADER_PAGED_BUF	help	  This option enables a sysfs loading facility to enable firmware	  loading to the kernel through userspace as a fallback mechanism	  if and only if the kernel's direct filesystem lookup for the	  firmware failed using the different /lib/firmware/ paths, or the	  path specified in the firmware_class path module parameter, or the	  firmware_class path kernel boot parameter if the firmware_class is	  built-in. For details on how to work with the sysfs fallback mechanism	  refer to Documentation/driver-api/firmware/fallback-mechanisms.rst. 	  The direct filesystem lookup for firmware is always used first now. 	  If the kernel's direct filesystem lookup for firmware fails to find	  the requested firmware a sysfs fallback loading facility is made	  available and userspace is informed about this through uevents.	  The uevent can be suppressed if the driver explicitly requested it,	  this is known as the driver using the custom fallback mechanism.	  If the custom fallback mechanism is used userspace must always	  acknowledge failure to find firmware as the timeout for the fallback	  mechanism is disabled, and failed requests will linger forever. 	  This used to be the default firmware loading facility, and udev used	  to listen for uvents to load firmware for the kernel. The firmware	  loading facility functionality in udev has been removed, as such it	  can no longer be relied upon as a fallback mechanism. Linux no longer	  relies on or uses a fallback mechanism in userspace. If you need to	  rely on one refer to the permissively licensed firmwared: 	  https://github.com/teg/firmwared 	  Since this was the default firmware loading facility at one point,	  old userspace may exist which relies upon it, and as such this	  mechanism can never be removed from the kernel. 	  You should only enable this functionality if you are certain you	  require a fallback mechanism and have a userspace mechanism ready to	  load firmware in case it is not found. One main reason for this may	  be if you have drivers which require firmware built-in and for	  whatever reason cannot place the required firmware in initramfs.	  Another reason kernels may have this feature enabled is to support a	  driver which explicitly relies on this fallback mechanism. Only two	  drivers need this today: 	    o CONFIG_LEDS_LP55XX_COMMON	    o CONFIG_DELL_RBU 	  Outside of supporting the above drivers, another reason for needing	  this may be that your firmware resides outside of the paths the kernel	  looks for and cannot possibly be specified using the firmware_class	  path module parameter or kernel firmware_class path boot parameter	  if firmware_class is built-in. 	  A modern use case may be to temporarily mount a custom partition	  during provisioning which is only accessible to userspace, and then	  to use it to look for and fetch the required firmware. Such type of	  driver functionality may not even ever be desirable upstream by	  vendors, and as such is only required to be supported as an interface	  for provisioning. Since udev's firmware loading facility has been	  removed you can use firmwared or a fork of it to customize how you	  want to load firmware based on uevents issued. 	  Enabling this option will increase your kernel image size by about	  13436 bytes. 	  If you are unsure about this, say N here, unless you are Linux	  distribution and need to support the above two drivers, or you are	  certain you need to support some really custom firmware loading	  facility in userspace. config FW_LOADER_USER_HELPER_FALLBACK	bool "Force the firmware sysfs fallback mechanism when possible"	depends on FW_LOADER_USER_HELPER	help	  Enabling this option forces a sysfs userspace fallback mechanism	  to be used for all firmware requests which explicitly do not disable a	  a fallback mechanism. Firmware calls which do prohibit a fallback	  mechanism is request_firmware_direct(). This option is kept for	  backward compatibility purposes given this precise mechanism can also	  be enabled by setting the proc sysctl value to true: 	       /proc/sys/kernel/firmware_config/force_sysfs_fallback 	  If you are unsure about this, say N here. config FW_LOADER_COMPRESS	bool "Enable compressed firmware support"	help	  This option enables the support for loading compressed firmware	  files. The caller of firmware API receives the decompressed file	  content. The compressed file is loaded as a fallback, only after	  loading the raw file failed at first. 	  Compressed firmware support does not apply to firmware images	  that are built into the kernel image (CONFIG_EXTRA_FIRMWARE). if FW_LOADER_COMPRESSconfig FW_LOADER_COMPRESS_XZ	bool "Enable XZ-compressed firmware support"	select FW_LOADER_PAGED_BUF	select XZ_DEC	default y	help	  This option adds the support for XZ-compressed files.	  The files have to be compressed with either none or crc32	  integrity check type (pass "-C crc32" option to xz command). config FW_LOADER_COMPRESS_ZSTD	bool "Enable ZSTD-compressed firmware support"	select ZSTD_DECOMPRESS	help	  This option adds the support for ZSTD-compressed files. endif # FW_LOADER_COMPRESS config FW_CACHE	bool "Enable firmware caching during suspend"	depends on PM_SLEEP	default y if PM_SLEEP	help	  Because firmware caching generates uevent messages that are sent	  over a netlink socket, it can prevent suspend on many platforms.	  It is also not always useful, so on such platforms we have the	  option. 	  If unsure, say Y. config FW_UPLOAD	bool "Enable users to initiate firmware updates using sysfs"	select FW_LOADER_SYSFS	select FW_LOADER_PAGED_BUF	help	  Enabling this option will allow device drivers to expose a persistent	  sysfs interface that allows firmware updates to be initiated from	  userspace. For example, FPGA based PCIe cards load firmware and FPGA	  images from local FLASH when the card boots. The images in FLASH may	  be updated with new images provided by the user. Enable this device	  to support cards that rely on user-initiated updates for firmware files. 	  If unsure, say N. endif # FW_LOADERendmenu