1# SPDX-License-Identifier: GPL-2.0
  2menu "Firmware loader"
  3
  4config FW_LOADER
  5	tristate "Firmware loading facility" if EXPERT
 
 
  6	default y
  7	help
  8	  This enables the firmware loading facility in the kernel. The kernel
  9	  will first look for built-in firmware, if it has any. Next, it will
 10	  look for the requested firmware in a series of filesystem paths:
 11
 12		o firmware_class path module parameter or kernel boot param
 13		o /lib/firmware/updates/UTS_RELEASE
 14		o /lib/firmware/updates
 15		o /lib/firmware/UTS_RELEASE
 16		o /lib/firmware
 17
 18	  Enabling this feature only increases your kernel image by about
 19	  828 bytes, enable this option unless you are certain you don't
 20	  need firmware.
 21
 22	  You typically want this built-in (=y) but you can also enable this
 23	  as a module, in which case the firmware_class module will be built.
 24	  You also want to be sure to enable this built-in if you are going to
 25	  enable built-in firmware (CONFIG_EXTRA_FIRMWARE).
 26
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 27if FW_LOADER
 28
 29config FW_LOADER_PAGED_BUF
 30	bool
 31
 
 
 
 32config EXTRA_FIRMWARE
 33	string "Build named firmware blobs into the kernel binary"
 34	help
 35	  Device drivers which require firmware can typically deal with
 36	  having the kernel load firmware from the various supported
 37	  /lib/firmware/ paths. This option enables you to build into the
 38	  kernel firmware files. Built-in firmware searches are preceded
 39	  over firmware lookups using your filesystem over the supported
 40	  /lib/firmware paths documented on CONFIG_FW_LOADER.
 41
 42	  This may be useful for testing or if the firmware is required early on
 43	  in boot and cannot rely on the firmware being placed in an initrd or
 44	  initramfs.
 45
 46	  This option is a string and takes the (space-separated) names of the
 47	  firmware files -- the same names that appear in MODULE_FIRMWARE()
 48	  and request_firmware() in the source. These files should exist under
 49	  the directory specified by the EXTRA_FIRMWARE_DIR option, which is
 50	  /lib/firmware by default.
 51
 52	  For example, you might set CONFIG_EXTRA_FIRMWARE="usb8388.bin", copy
 53	  the usb8388.bin file into /lib/firmware, and build the kernel. Then
 54	  any request_firmware("usb8388.bin") will be satisfied internally
 55	  inside the kernel without ever looking at your filesystem at runtime.
 56
 57	  WARNING: If you include additional firmware files into your binary
 58	  kernel image that are not available under the terms of the GPL,
 59	  then it may be a violation of the GPL to distribute the resulting
 60	  image since it combines both GPL and non-GPL work. You should
 61	  consult a lawyer of your own before distributing such an image.
 62
 
 
 63config EXTRA_FIRMWARE_DIR
 64	string "Firmware blobs root directory"
 65	depends on EXTRA_FIRMWARE != ""
 66	default "/lib/firmware"
 67	help
 68	  This option controls the directory in which the kernel build system
 69	  looks for the firmware files listed in the EXTRA_FIRMWARE option.
 70
 71config FW_LOADER_USER_HELPER
 72	bool "Enable the firmware sysfs fallback mechanism"
 
 73	select FW_LOADER_PAGED_BUF
 74	help
 75	  This option enables a sysfs loading facility to enable firmware
 76	  loading to the kernel through userspace as a fallback mechanism
 77	  if and only if the kernel's direct filesystem lookup for the
 78	  firmware failed using the different /lib/firmware/ paths, or the
 79	  path specified in the firmware_class path module parameter, or the
 80	  firmware_class path kernel boot parameter if the firmware_class is
 81	  built-in. For details on how to work with the sysfs fallback mechanism
 82	  refer to Documentation/driver-api/firmware/fallback-mechanisms.rst.
 83
 84	  The direct filesystem lookup for firmware is always used first now.
 85
 86	  If the kernel's direct filesystem lookup for firmware fails to find
 87	  the requested firmware a sysfs fallback loading facility is made
 88	  available and userspace is informed about this through uevents.
 89	  The uevent can be suppressed if the driver explicitly requested it,
 90	  this is known as the driver using the custom fallback mechanism.
 91	  If the custom fallback mechanism is used userspace must always
 92	  acknowledge failure to find firmware as the timeout for the fallback
 93	  mechanism is disabled, and failed requests will linger forever.
 94
 95	  This used to be the default firmware loading facility, and udev used
 96	  to listen for uvents to load firmware for the kernel. The firmware
 97	  loading facility functionality in udev has been removed, as such it
 98	  can no longer be relied upon as a fallback mechanism. Linux no longer
 99	  relies on or uses a fallback mechanism in userspace. If you need to
100	  rely on one refer to the permissively licensed firmwared:
101
102	  https://github.com/teg/firmwared
103
104	  Since this was the default firmware loading facility at one point,
105	  old userspace may exist which relies upon it, and as such this
106	  mechanism can never be removed from the kernel.
107
108	  You should only enable this functionality if you are certain you
109	  require a fallback mechanism and have a userspace mechanism ready to
110	  load firmware in case it is not found. One main reason for this may
111	  be if you have drivers which require firmware built-in and for
112	  whatever reason cannot place the required firmware in initramfs.
113	  Another reason kernels may have this feature enabled is to support a
114	  driver which explicitly relies on this fallback mechanism. Only two
115	  drivers need this today:
116
117	    o CONFIG_LEDS_LP55XX_COMMON
118	    o CONFIG_DELL_RBU
119
120	  Outside of supporting the above drivers, another reason for needing
121	  this may be that your firmware resides outside of the paths the kernel
122	  looks for and cannot possibly be specified using the firmware_class
123	  path module parameter or kernel firmware_class path boot parameter
124	  if firmware_class is built-in.
125
126	  A modern use case may be to temporarily mount a custom partition
127	  during provisioning which is only accessible to userspace, and then
128	  to use it to look for and fetch the required firmware. Such type of
129	  driver functionality may not even ever be desirable upstream by
130	  vendors, and as such is only required to be supported as an interface
131	  for provisioning. Since udev's firmware loading facility has been
132	  removed you can use firmwared or a fork of it to customize how you
133	  want to load firmware based on uevents issued.
134
135	  Enabling this option will increase your kernel image size by about
136	  13436 bytes.
137
138	  If you are unsure about this, say N here, unless you are Linux
139	  distribution and need to support the above two drivers, or you are
140	  certain you need to support some really custom firmware loading
141	  facility in userspace.
142
143config FW_LOADER_USER_HELPER_FALLBACK
144	bool "Force the firmware sysfs fallback mechanism when possible"
145	depends on FW_LOADER_USER_HELPER
146	help
147	  Enabling this option forces a sysfs userspace fallback mechanism
148	  to be used for all firmware requests which explicitly do not disable a
149	  a fallback mechanism. Firmware calls which do prohibit a fallback
150	  mechanism is request_firmware_direct(). This option is kept for
151	  backward compatibility purposes given this precise mechanism can also
152	  be enabled by setting the proc sysctl value to true:
153
154	       /proc/sys/kernel/firmware_config/force_sysfs_fallback
155
156	  If you are unsure about this, say N here.
157
158config FW_LOADER_COMPRESS
159	bool "Enable compressed firmware support"
160	select FW_LOADER_PAGED_BUF
161	select XZ_DEC
162	help
163	  This option enables the support for loading compressed firmware
164	  files. The caller of firmware API receives the decompressed file
165	  content. The compressed file is loaded as a fallback, only after
166	  loading the raw file failed at first.
167
168	  Currently only XZ-compressed files are supported, and they have to
169	  be compressed with either none or crc32 integrity check type (pass
170	  "-C crc32" option to xz command).
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
171
172config FW_CACHE
173	bool "Enable firmware caching during suspend"
174	depends on PM_SLEEP
175	default y if PM_SLEEP
176	help
177	  Because firmware caching generates uevent messages that are sent
178	  over a netlink socket, it can prevent suspend on many platforms.
179	  It is also not always useful, so on such platforms we have the
180	  option.
181
182	  If unsure, say Y.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
183
184endif # FW_LOADER
185endmenu

  1# SPDX-License-Identifier: GPL-2.0
  2menu "Firmware loader"
  3
  4config FW_LOADER
  5	tristate "Firmware loading facility" if EXPERT
  6	select CRYPTO_HASH if FW_LOADER_DEBUG
  7	select CRYPTO_SHA256 if FW_LOADER_DEBUG
  8	default y
  9	help
 10	  This enables the firmware loading facility in the kernel. The kernel
 11	  will first look for built-in firmware, if it has any. Next, it will
 12	  look for the requested firmware in a series of filesystem paths:
 13
 14		o firmware_class path module parameter or kernel boot param
 15		o /lib/firmware/updates/UTS_RELEASE
 16		o /lib/firmware/updates
 17		o /lib/firmware/UTS_RELEASE
 18		o /lib/firmware
 19
 20	  Enabling this feature only increases your kernel image by about
 21	  828 bytes, enable this option unless you are certain you don't
 22	  need firmware.
 23
 24	  You typically want this built-in (=y) but you can also enable this
 25	  as a module, in which case the firmware_class module will be built.
 26	  You also want to be sure to enable this built-in if you are going to
 27	  enable built-in firmware (CONFIG_EXTRA_FIRMWARE).
 28
 29config FW_LOADER_DEBUG
 30	bool "Log filenames and checksums for loaded firmware"
 31	depends on CRYPTO = FW_LOADER || CRYPTO=y
 32	depends on DYNAMIC_DEBUG
 33	depends on FW_LOADER
 34	default FW_LOADER
 35	help
 36	  Select this option to use dynamic debug to log firmware filenames and
 37	  SHA256 checksums to the kernel log for each firmware file that is
 38	  loaded.
 39
 40config RUST_FW_LOADER_ABSTRACTIONS
 41	bool "Rust Firmware Loader abstractions"
 42	depends on RUST
 43	depends on FW_LOADER=y
 44	help
 45	  This enables the Rust abstractions for the firmware loader API.
 46
 47if FW_LOADER
 48
 49config FW_LOADER_PAGED_BUF
 50	bool
 51
 52config FW_LOADER_SYSFS
 53	bool
 54
 55config EXTRA_FIRMWARE
 56	string "Build named firmware blobs into the kernel binary"
 57	help
 58	  Device drivers which require firmware can typically deal with
 59	  having the kernel load firmware from the various supported
 60	  /lib/firmware/ paths. This option enables you to build into the
 61	  kernel firmware files. Built-in firmware searches are preceded
 62	  over firmware lookups using your filesystem over the supported
 63	  /lib/firmware paths documented on CONFIG_FW_LOADER.
 64
 65	  This may be useful for testing or if the firmware is required early on
 66	  in boot and cannot rely on the firmware being placed in an initrd or
 67	  initramfs.
 68
 69	  This option is a string and takes the (space-separated) names of the
 70	  firmware files -- the same names that appear in MODULE_FIRMWARE()
 71	  and request_firmware() in the source. These files should exist under
 72	  the directory specified by the EXTRA_FIRMWARE_DIR option, which is
 73	  /lib/firmware by default.
 74
 75	  For example, you might set CONFIG_EXTRA_FIRMWARE="usb8388.bin", copy
 76	  the usb8388.bin file into /lib/firmware, and build the kernel. Then
 77	  any request_firmware("usb8388.bin") will be satisfied internally
 78	  inside the kernel without ever looking at your filesystem at runtime.
 79
 80	  WARNING: If you include additional firmware files into your binary
 81	  kernel image that are not available under the terms of the GPL,
 82	  then it may be a violation of the GPL to distribute the resulting
 83	  image since it combines both GPL and non-GPL work. You should
 84	  consult a lawyer of your own before distributing such an image.
 85
 86	  NOTE: Compressed files are not supported in EXTRA_FIRMWARE.
 87
 88config EXTRA_FIRMWARE_DIR
 89	string "Firmware blobs root directory"
 90	depends on EXTRA_FIRMWARE != ""
 91	default "/lib/firmware"
 92	help
 93	  This option controls the directory in which the kernel build system
 94	  looks for the firmware files listed in the EXTRA_FIRMWARE option.
 95
 96config FW_LOADER_USER_HELPER
 97	bool "Enable the firmware sysfs fallback mechanism"
 98	select FW_LOADER_SYSFS
 99	select FW_LOADER_PAGED_BUF
100	help
101	  This option enables a sysfs loading facility to enable firmware
102	  loading to the kernel through userspace as a fallback mechanism
103	  if and only if the kernel's direct filesystem lookup for the
104	  firmware failed using the different /lib/firmware/ paths, or the
105	  path specified in the firmware_class path module parameter, or the
106	  firmware_class path kernel boot parameter if the firmware_class is
107	  built-in. For details on how to work with the sysfs fallback mechanism
108	  refer to Documentation/driver-api/firmware/fallback-mechanisms.rst.
109
110	  The direct filesystem lookup for firmware is always used first now.
111
112	  If the kernel's direct filesystem lookup for firmware fails to find
113	  the requested firmware a sysfs fallback loading facility is made
114	  available and userspace is informed about this through uevents.
115	  The uevent can be suppressed if the driver explicitly requested it,
116	  this is known as the driver using the custom fallback mechanism.
117	  If the custom fallback mechanism is used userspace must always
118	  acknowledge failure to find firmware as the timeout for the fallback
119	  mechanism is disabled, and failed requests will linger forever.
120
121	  This used to be the default firmware loading facility, and udev used
122	  to listen for uvents to load firmware for the kernel. The firmware
123	  loading facility functionality in udev has been removed, as such it
124	  can no longer be relied upon as a fallback mechanism. Linux no longer
125	  relies on or uses a fallback mechanism in userspace. If you need to
126	  rely on one refer to the permissively licensed firmwared:
127
128	  https://github.com/teg/firmwared
129
130	  Since this was the default firmware loading facility at one point,
131	  old userspace may exist which relies upon it, and as such this
132	  mechanism can never be removed from the kernel.
133
134	  You should only enable this functionality if you are certain you
135	  require a fallback mechanism and have a userspace mechanism ready to
136	  load firmware in case it is not found. One main reason for this may
137	  be if you have drivers which require firmware built-in and for
138	  whatever reason cannot place the required firmware in initramfs.
139	  Another reason kernels may have this feature enabled is to support a
140	  driver which explicitly relies on this fallback mechanism. Only two
141	  drivers need this today:
142
143	    o CONFIG_LEDS_LP55XX_COMMON
144	    o CONFIG_DELL_RBU
145
146	  Outside of supporting the above drivers, another reason for needing
147	  this may be that your firmware resides outside of the paths the kernel
148	  looks for and cannot possibly be specified using the firmware_class
149	  path module parameter or kernel firmware_class path boot parameter
150	  if firmware_class is built-in.
151
152	  A modern use case may be to temporarily mount a custom partition
153	  during provisioning which is only accessible to userspace, and then
154	  to use it to look for and fetch the required firmware. Such type of
155	  driver functionality may not even ever be desirable upstream by
156	  vendors, and as such is only required to be supported as an interface
157	  for provisioning. Since udev's firmware loading facility has been
158	  removed you can use firmwared or a fork of it to customize how you
159	  want to load firmware based on uevents issued.
160
161	  Enabling this option will increase your kernel image size by about
162	  13436 bytes.
163
164	  If you are unsure about this, say N here, unless you are Linux
165	  distribution and need to support the above two drivers, or you are
166	  certain you need to support some really custom firmware loading
167	  facility in userspace.
168
169config FW_LOADER_USER_HELPER_FALLBACK
170	bool "Force the firmware sysfs fallback mechanism when possible"
171	depends on FW_LOADER_USER_HELPER
172	help
173	  Enabling this option forces a sysfs userspace fallback mechanism
174	  to be used for all firmware requests which explicitly do not disable a
175	  a fallback mechanism. Firmware calls which do prohibit a fallback
176	  mechanism is request_firmware_direct(). This option is kept for
177	  backward compatibility purposes given this precise mechanism can also
178	  be enabled by setting the proc sysctl value to true:
179
180	       /proc/sys/kernel/firmware_config/force_sysfs_fallback
181
182	  If you are unsure about this, say N here.
183
184config FW_LOADER_COMPRESS
185	bool "Enable compressed firmware support"
 
 
186	help
187	  This option enables the support for loading compressed firmware
188	  files. The caller of firmware API receives the decompressed file
189	  content. The compressed file is loaded as a fallback, only after
190	  loading the raw file failed at first.
191
192	  Compressed firmware support does not apply to firmware images
193	  that are built into the kernel image (CONFIG_EXTRA_FIRMWARE).
194
195if FW_LOADER_COMPRESS
196config FW_LOADER_COMPRESS_XZ
197	bool "Enable XZ-compressed firmware support"
198	select FW_LOADER_PAGED_BUF
199	select XZ_DEC
200	default y
201	help
202	  This option adds the support for XZ-compressed files.
203	  The files have to be compressed with either none or crc32
204	  integrity check type (pass "-C crc32" option to xz command).
205
206config FW_LOADER_COMPRESS_ZSTD
207	bool "Enable ZSTD-compressed firmware support"
208	select ZSTD_DECOMPRESS
209	help
210	  This option adds the support for ZSTD-compressed files.
211
212endif # FW_LOADER_COMPRESS
213
214config FW_CACHE
215	bool "Enable firmware caching during suspend"
216	depends on PM_SLEEP
217	default y if PM_SLEEP
218	help
219	  Because firmware caching generates uevent messages that are sent
220	  over a netlink socket, it can prevent suspend on many platforms.
221	  It is also not always useful, so on such platforms we have the
222	  option.
223
224	  If unsure, say Y.
225
226config FW_UPLOAD
227	bool "Enable users to initiate firmware updates using sysfs"
228	select FW_LOADER_SYSFS
229	select FW_LOADER_PAGED_BUF
230	help
231	  Enabling this option will allow device drivers to expose a persistent
232	  sysfs interface that allows firmware updates to be initiated from
233	  userspace. For example, FPGA based PCIe cards load firmware and FPGA
234	  images from local FLASH when the card boots. The images in FLASH may
235	  be updated with new images provided by the user. Enable this device
236	  to support cards that rely on user-initiated updates for firmware files.
237
238	  If unsure, say N.
239
240endif # FW_LOADER
241endmenu