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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
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