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