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24 .\" $FreeBSD: src/share/man/man9/firmware.9,v 1.9 2010/04/14 19:08:06 uqs Exp $
30 .Nm firmware_register ,
31 .Nm firmware_unregister ,
34 .Nd firmware image loading and management
42 const char *name; /* system-wide name */
43 const void *data; /* location of image */
44 size_t datasize; /* size of image in bytes */
45 unsigned int version; /* version of the image */
48 .Ft "const struct firmware *"
50 .Fa "const char *imagename"
51 .Fa "const void *data"
53 .Fa "unsigned int version"
54 .Fa "const struct firmware *parent"
57 .Fn firmware_unregister "const char *imagename"
58 .Ft "const struct firmware *"
59 .Fn firmware_get "const char *imagename"
61 .Fn firmware_put "const struct firmware *fp" "int flags"
65 abstraction provides a convenient interface for loading
67 into the kernel, and for accessing such images from kernel components.
74 is an opaque block of data residing in kernel memory.
75 It is associated to a unique
77 which constitutes a search key, and to an integer
79 number, which is also an opaque piece of information for the
82 An image is registered with the
84 subsystem by calling the function
85 .Fn firmware_register ,
86 and unregistered by calling
87 .Fn firmware_unregister .
88 These functions are usually (but not exclusively) called by
89 specially crafted kernel modules that contain the firmware image.
90 The modules can be statically compiled in the kernel, or loaded by
92 manually at runtime, or on demand by the firmware subsystem.
95 of the firmware subsystem can request access to a given image
96 by calling the function
100 they want as an argument. If a matching image is not already registered,
101 the firmware subsystem will try to load it using the
102 mechanisms specified below (typically, a kernel module
109 is made of the following functions:
111 .Fn firmware_register
112 registers with the kernel an image of size
119 The function returns NULL on error (e.g. because an
120 image with the same name already exists, or the image
122 .Ft const struct firmware *
123 pointer to the image requested.
125 .Fn firmware_unregister
126 tries to unregister the firmware image
128 from the system. The function is successful and returns 0
129 if there are no pending references to the image, otherwise
130 it does not unregister the image and returns
134 returns the requested firmware image.
135 If the image is not yet registered with the system,
136 the function tries to load it.
137 This involves the linker subsystem and disk access, so
139 must not be called with any locks (except for
141 Note also that if the firmware image is loaded from a filesystem
142 it must already be mounted.
143 In particular this means that it may be necessary to defer requests
144 from a driver attach method unless it is known the root filesystem is
149 returns a pointer to the image description and increases the reference count
150 for this image. On failure, the function returns NULL.
153 drops a reference to a firmware image.
156 argument may be set to
159 firmware_put is free to reclaim resources associated with
160 the firmware image if this is the last reference.
161 By default a firmware image will be deferred to a
163 thread so the call may be done while holding a lock.
164 In certain cases, such as on driver detach, this cannot be allowed.
165 .Sh FIRMWARE LOADING MECHANISMS
166 As mentioned before, any component of the system can register
167 firmware images at any time by simply calling
168 .Fn firmware_register .
170 This is typically done when a module containing
171 a firmware image is given control,
172 whether compiled in, or preloaded by
174 or manually loaded with
176 However, a system can implement additional mechanisms to bring
177 these images in memory before calling
178 .Fn firmware_register .
182 does not find the requested image, it tries to load it using
183 one of the available loading mechanisms.
184 At the moment, there is only one, namely
185 .Nm Loadable kernel modules :
187 A firmware image named
189 is looked up by trying to load the module named
191 using the facilities described in
193 In particular, images are looked up in the directories specified
194 by the sysctl variable
196 which on most systems defaults to
197 .Nm /boot/kernel;/boot/modules .
199 Note that in case a module contains multiple images,
200 the caller should first request a
202 for the first image contained in the module, followed by requests
203 for the other images.
204 .Sh BUILDING FIRMWARE LOADABLE MODULES
205 A firmware module is built by embedding the
207 into a suitable loadable kernel module that calls
208 .Fn firmware_register
210 .Fn firmware_unregister
213 Various system scripts and makefiles let you build a module
214 by simply writing a Makefile with the following entries:
218 FIRMWS= image_file:imagename[:version]
219 .include <bsd.kmod.mk>
222 where KMOD is the basename of the module; FIRMWS is a list of
223 colon-separated tuples indicating the image_file's to be embedded
224 in the module, the imagename and version of each firmware image.
226 If you need to embed firmware images into a system, you should write
227 appropriate entries in the
234 wpifw.c optional wpifw \\
235 dependency "$S/contrib/dev/wpi/iwlwifi-3945-2.14.4.fw.uu" \\
236 compile-with "${AWK} -f $S/tools/fw_stub.awk wpi.fw:wpifw:2144 -mwpifw -c${.TARGET}" \\
237 no-implicit-rule before-depend local \\
239 wpifw.fwo optional wpifw \\
240 dependency "wpi.fw" \\
241 compile-with "${LD} -b binary -d -warn-common -r -d -o ${.TARGET} wpi.fw" \\
244 wpi.fw optional wpifw \\
245 dependency "$S/contrib/dev/wpi/iwlwifi-3945-2.14.4.fw.uu" \\
246 compile-with "uudecode -o ${.TARGET} $S/contrib/dev/wpi/iwlwifi-3945-2.14.4.fw.uu" \\
247 no-obj no-implicit-rule \\
251 Note that generating the firmware modules in this way requires
252 the availability of the following tools:
255 the compiler and the linker.
260 .Pa /usr/share/examples/kld/firmware
264 system was introduced in
267 This manual page was written by
268 .An Max Laier Aq Mt mlaier@FreeBSD.org .