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Хостинг:
firmware_register firmware_unregister firmware_get firmware_put - firmware image loading and management
struct firmware {
const char *name; /* system-wide name */
const void *data; /* location of image */
size_t datasize; /* size of image in bytes */
unsigned int version; /* version of the image */
};
const struct firmware *
Fo firmware_register
Fa const char *imagename
Fa const void *data
Fa size_t datasize
Fa unsigned int version
Fa const struct firmware *parent
Fc Ft int
firmware_unregister (const char *imagename);A firmware image (or image for brevity) is an opaque block of data residing in kernel memory. It is associated to a unique imagename which constitutes a search key, and to an integer version number, which is also an opaque piece of information for the firmware subsystem.
An image is registered with the
firmware
subsystem by calling the function
firmware_register (,);
and unregistered by calling
firmware_unregister (.);
These functions are usually (but not exclusively) called by
specially crafted kernel modules that contain the firmware image.
The modules can be statically compiled in the kernel, or loaded by
/boot/loader
manually at runtime, or on demand by the firmware subsystem.
Clients
of the firmware subsystem can request access to a given image
by calling the function
firmware_get ();
with the
imagename
they want as an argument. If a matching image is not already registered,
the firmware subsystem will try to load it using the
mechanisms specified below (typically, a kernel module
with
the same name
as the image).
firmware_register ();
registers with the kernel an image of size
datasize
located at address
data
under the name
imagename
The function returns NULL on error (e.g. because an image with the same name already exists, or the image table is full), or a const struct firmware * pointer to the image requested.
firmware_unregister ();
tries to unregister the firmware image
imagename
from the system. The function is successful and returns 0
if there are no pending references to the image, otherwise
it does not unregister the image and returns EBUSY.
firmware_get ();
returns the requested firmware image.
If the image is not yet registered with the system,
the function tries to load it.
This involves the linker subsystem and disk access, so
firmware_get ();
must not be called with any locks (except for
Giant )
The caller must also have a process context so filesystem state such as
the root vnode is defined (e.g. you cannot load from a taskqueue thread).
On success,
firmware_get ();
returns a pointer to the image description and increases the reference count
for this image. On failure, the function returns NULL.
firmware_put ();
drops a reference to a firmware image.
The
Fa flags
argument may be set to
FIRMWARE_UNLOAD
to indicate that
firmware_put is free to reclaim resources associated with
the firmware image if this is the last reference.
This is typically done when a module containing
a firmware image is given control,
whether compiled in, or preloaded by
/boot/loader
or manually loaded with
kldload(8).
However, a system can implement additional mechanisms to bring
these images in memory before calling
firmware_register (.);
When
firmware_get ();
does not find the requested image, it tries to load it using
one of the available loading mechanisms.
At the moment, there is only one, namely
Loadable kernel modules
A firmware image named foo is looked up by trying to load the module named foo.ko using the facilities described in kld(4). In particular, images are looked up in the directories specified by the sysctl variable kern.module_path which on most systems defaults to /boot/kernel;/boot/modules
Note that in case a module contains multiple images,
the caller should first request a
firmware_get ();
for the first image contained in the module, followed by requests
for the other images.
Various system scripts and makefiles let you build a module by simply writing a Makefile with the following entries:
KMOD= imagename
FIRMWS= image_file:imagename[:version]
.include <bsd.kmod.mk>
where KMOD is the basename of the module; FIRMWS is a list of
colon-separated tuples indicating the image_file's to be embedded
in the module, the imagename and version of each firmware image.
If you need to embed firmware images into a system, you should write appropriate entries in the <files.arch> file, e.g. this example is from sys/arm/xscale/ixp425/files.ixp425:
ixp425_npe_fw.c optional npe_fw \
compile-with "${AWK} -f $S/tools/fw_stub.awk \
IxNpeMicrocode.dat:npe_fw -mnpe -c${.TARGET}" \
no-implicit-rule before-depend local \
clean "ixp425_npe_fw.c"
#
# NB: ld encodes the path in the binary symbols generated for the
# firmware image so link the file to the object directory to
# get known values for reference in the _fw.c file.
#
IxNpeMicrocode.fwo optional npe_fw \
dependency "IxNpeMicrocode.dat" \
compile-with "${LD} -b binary -d -warn-common \
-r -d -o ${.TARGET} IxNpeMicrocode.dat" \
no-implicit-rule \
clean "IxNpeMicrocode.fwo"
IxNpeMicrocode.dat optional npe_fw \
dependency ".PHONY" \
compile-with "if [ -e $S/arm/xscale/ixp425/IxNpeMicrocode.dat ]; \
then \
ln -sf $S/arm/xscale/ixp425/IxNpeMicrocode.dat .; \
else echo 'WARNING, no IxNpeMicrocode.dat file; you must obtain this from the Intel web site'; false; \
fi" \
no-obj no-implicit-rule \
clean "IxNpeMicrocode.dat"
Note that generating the firmware modules in this way requires the availability of the following tools: awk, Make, the compiler and the linker.
/usr/share/examples/kld/firmware
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