firmware_loader: move kconfig FW_LOADER entries to its own file
This will make it easier to track and easier to understand what components and features are part of the FW_LOADER. There are some components related to firmware which have *nothing* to do with the FW_LOADER, souch as PREVENT_FIRMWARE_BUILD. Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Luis R. Rodriguez
Greg Kroah-Hartman
Родитель
367d098241
Коммит
06bfd3c8ab
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@ -88,160 +88,7 @@ config PREVENT_FIRMWARE_BUILD
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o CONFIG_WANXL through CONFIG_WANXL_BUILD_FIRMWARE
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o CONFIG_SCSI_AIC79XX through CONFIG_AIC79XX_BUILD_FIRMWARE
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menu "Firmware loader"
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config FW_LOADER
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tristate "Firmware loading facility" if EXPERT
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default y
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help
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This enables the firmware loading facility in the kernel. The kernel
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will first look for built-in firmware, if it has any. Next, it will
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look for the requested firmware in a series of filesystem paths:
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o firmware_class path module parameter or kernel boot param
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o /lib/firmware/updates/UTS_RELEASE
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o /lib/firmware/updates
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o /lib/firmware/UTS_RELEASE
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o /lib/firmware
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Enabling this feature only increases your kernel image by about
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828 bytes, enable this option unless you are certain you don't
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need firmware.
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You typically want this built-in (=y) but you can also enable this
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as a module, in which case the firmware_class module will be built.
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You also want to be sure to enable this built-in if you are going to
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enable built-in firmware (CONFIG_EXTRA_FIRMWARE).
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if FW_LOADER
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config EXTRA_FIRMWARE
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string "Build named firmware blobs into the kernel binary"
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help
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Device drivers which require firmware can typically deal with
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having the kernel load firmware from the various supported
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||||
/lib/firmware/ paths. This option enables you to build into the
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||||
kernel firmware files. Built-in firmware searches are preceded
|
||||
over firmware lookups using your filesystem over the supported
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/lib/firmware paths documented on CONFIG_FW_LOADER.
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This may be useful for testing or if the firmware is required early on
|
||||
in boot and cannot rely on the firmware being placed in an initrd or
|
||||
initramfs.
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||||
|
||||
This option is a string and takes the (space-separated) names of the
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firmware files -- the same names that appear in MODULE_FIRMWARE()
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and request_firmware() in the source. These files should exist under
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the directory specified by the EXTRA_FIRMWARE_DIR option, which is
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/lib/firmware by default.
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For example, you might set CONFIG_EXTRA_FIRMWARE="usb8388.bin", copy
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the usb8388.bin file into /lib/firmware, and build the kernel. Then
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any request_firmware("usb8388.bin") will be satisfied internally
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||||
inside the kernel without ever looking at your filesystem at runtime.
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||||
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WARNING: If you include additional firmware files into your binary
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kernel image that are not available under the terms of the GPL,
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||||
then it may be a violation of the GPL to distribute the resulting
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||||
image since it combines both GPL and non-GPL work. You should
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||||
consult a lawyer of your own before distributing such an image.
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config EXTRA_FIRMWARE_DIR
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string "Firmware blobs root directory"
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depends on EXTRA_FIRMWARE != ""
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default "/lib/firmware"
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help
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This option controls the directory in which the kernel build system
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looks for the firmware files listed in the EXTRA_FIRMWARE option.
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config FW_LOADER_USER_HELPER
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bool "Enable the firmware sysfs fallback mechanism"
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help
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This option enables a sysfs loading facility to enable firmware
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loading to the kernel through userspace as a fallback mechanism
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if and only if the kernel's direct filesystem lookup for the
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firmware failed using the different /lib/firmware/ paths, or the
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path specified in the firmware_class path module parameter, or the
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firmware_class path kernel boot parameter if the firmware_class is
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built-in. For details on how to work with the sysfs fallback mechanism
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refer to Documentation/driver-api/firmware/fallback-mechanisms.rst.
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The direct filesystem lookup for firmware is always used first now.
|
||||
|
||||
If the kernel's direct filesystem lookup for firmware fails to find
|
||||
the requested firmware a sysfs fallback loading facility is made
|
||||
available and userspace is informed about this through uevents.
|
||||
The uevent can be suppressed if the driver explicitly requested it,
|
||||
this is known as the driver using the custom fallback mechanism.
|
||||
If the custom fallback mechanism is used userspace must always
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||||
acknowledge failure to find firmware as the timeout for the fallback
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||||
mechanism is disabled, and failed requests will linger forever.
|
||||
|
||||
This used to be the default firmware loading facility, and udev used
|
||||
to listen for uvents to load firmware for the kernel. The firmware
|
||||
loading facility functionality in udev has been removed, as such it
|
||||
can no longer be relied upon as a fallback mechanism. Linux no longer
|
||||
relies on or uses a fallback mechanism in userspace. If you need to
|
||||
rely on one refer to the permissively licensed firmwared:
|
||||
|
||||
https://github.com/teg/firmwared
|
||||
|
||||
Since this was the default firmware loading facility at one point,
|
||||
old userspace may exist which relies upon it, and as such this
|
||||
mechanism can never be removed from the kernel.
|
||||
|
||||
You should only enable this functionality if you are certain you
|
||||
require a fallback mechanism and have a userspace mechanism ready to
|
||||
load firmware in case it is not found. One main reason for this may
|
||||
be if you have drivers which require firmware built-in and for
|
||||
whatever reason cannot place the required firmware in initramfs.
|
||||
Another reason kernels may have this feature enabled is to support a
|
||||
driver which explicitly relies on this fallback mechanism. Only two
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drivers need this today:
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||||
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o CONFIG_LEDS_LP55XX_COMMON
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o CONFIG_DELL_RBU
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Outside of supporting the above drivers, another reason for needing
|
||||
this may be that your firmware resides outside of the paths the kernel
|
||||
looks for and cannot possibly be specified using the firmware_class
|
||||
path module parameter or kernel firmware_class path boot parameter
|
||||
if firmware_class is built-in.
|
||||
|
||||
A modern use case may be to temporarily mount a custom partition
|
||||
during provisioning which is only accessible to userspace, and then
|
||||
to use it to look for and fetch the required firmware. Such type of
|
||||
driver functionality may not even ever be desirable upstream by
|
||||
vendors, and as such is only required to be supported as an interface
|
||||
for provisioning. Since udev's firmware loading facility has been
|
||||
removed you can use firmwared or a fork of it to customize how you
|
||||
want to load firmware based on uevents issued.
|
||||
|
||||
Enabling this option will increase your kernel image size by about
|
||||
13436 bytes.
|
||||
|
||||
If you are unsure about this, say N here, unless you are Linux
|
||||
distribution and need to support the above two drivers, or you are
|
||||
certain you need to support some really custom firmware loading
|
||||
facility in userspace.
|
||||
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config FW_LOADER_USER_HELPER_FALLBACK
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bool "Force the firmware sysfs fallback mechanism when possible"
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depends on FW_LOADER_USER_HELPER
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help
|
||||
Enabling this option forces a sysfs userspace fallback mechanism
|
||||
to be used for all firmware requests which explicitly do not disable a
|
||||
a fallback mechanism. Firmware calls which do prohibit a fallback
|
||||
mechanism is request_firmware_direct(). This option is kept for
|
||||
backward compatibility purposes given this precise mechanism can also
|
||||
be enabled by setting the proc sysctl value to true:
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||||
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/proc/sys/kernel/firmware_config/force_sysfs_fallback
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If you are unsure about this, say N here.
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endif # FW_LOADER
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endmenu
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source "drivers/base/firmware_loader/Kconfig"
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config WANT_DEV_COREDUMP
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bool
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@ -0,0 +1,154 @@
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menu "Firmware loader"
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||||
|
||||
config FW_LOADER
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||||
tristate "Firmware loading facility" if EXPERT
|
||||
default y
|
||||
help
|
||||
This enables the firmware loading facility in the kernel. The kernel
|
||||
will first look for built-in firmware, if it has any. Next, it will
|
||||
look for the requested firmware in a series of filesystem paths:
|
||||
|
||||
o firmware_class path module parameter or kernel boot param
|
||||
o /lib/firmware/updates/UTS_RELEASE
|
||||
o /lib/firmware/updates
|
||||
o /lib/firmware/UTS_RELEASE
|
||||
o /lib/firmware
|
||||
|
||||
Enabling this feature only increases your kernel image by about
|
||||
828 bytes, enable this option unless you are certain you don't
|
||||
need firmware.
|
||||
|
||||
You typically want this built-in (=y) but you can also enable this
|
||||
as a module, in which case the firmware_class module will be built.
|
||||
You also want to be sure to enable this built-in if you are going to
|
||||
enable built-in firmware (CONFIG_EXTRA_FIRMWARE).
|
||||
|
||||
if FW_LOADER
|
||||
|
||||
config EXTRA_FIRMWARE
|
||||
string "Build named firmware blobs into the kernel binary"
|
||||
help
|
||||
Device drivers which require firmware can typically deal with
|
||||
having the kernel load firmware from the various supported
|
||||
/lib/firmware/ paths. This option enables you to build into the
|
||||
kernel firmware files. Built-in firmware searches are preceded
|
||||
over firmware lookups using your filesystem over the supported
|
||||
/lib/firmware paths documented on CONFIG_FW_LOADER.
|
||||
|
||||
This may be useful for testing or if the firmware is required early on
|
||||
in boot and cannot rely on the firmware being placed in an initrd or
|
||||
initramfs.
|
||||
|
||||
This option is a string and takes the (space-separated) names of the
|
||||
firmware files -- the same names that appear in MODULE_FIRMWARE()
|
||||
and request_firmware() in the source. These files should exist under
|
||||
the directory specified by the EXTRA_FIRMWARE_DIR option, which is
|
||||
/lib/firmware by default.
|
||||
|
||||
For example, you might set CONFIG_EXTRA_FIRMWARE="usb8388.bin", copy
|
||||
the usb8388.bin file into /lib/firmware, and build the kernel. Then
|
||||
any request_firmware("usb8388.bin") will be satisfied internally
|
||||
inside the kernel without ever looking at your filesystem at runtime.
|
||||
|
||||
WARNING: If you include additional firmware files into your binary
|
||||
kernel image that are not available under the terms of the GPL,
|
||||
then it may be a violation of the GPL to distribute the resulting
|
||||
image since it combines both GPL and non-GPL work. You should
|
||||
consult a lawyer of your own before distributing such an image.
|
||||
|
||||
config EXTRA_FIRMWARE_DIR
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string "Firmware blobs root directory"
|
||||
depends on EXTRA_FIRMWARE != ""
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default "/lib/firmware"
|
||||
help
|
||||
This option controls the directory in which the kernel build system
|
||||
looks for the firmware files listed in the EXTRA_FIRMWARE option.
|
||||
|
||||
config FW_LOADER_USER_HELPER
|
||||
bool "Enable the firmware sysfs fallback mechanism"
|
||||
help
|
||||
This option enables a sysfs loading facility to enable firmware
|
||||
loading to the kernel through userspace as a fallback mechanism
|
||||
if and only if the kernel's direct filesystem lookup for the
|
||||
firmware failed using the different /lib/firmware/ paths, or the
|
||||
path specified in the firmware_class path module parameter, or the
|
||||
firmware_class path kernel boot parameter if the firmware_class is
|
||||
built-in. For details on how to work with the sysfs fallback mechanism
|
||||
refer to Documentation/driver-api/firmware/fallback-mechanisms.rst.
|
||||
|
||||
The direct filesystem lookup for firmware is always used first now.
|
||||
|
||||
If the kernel's direct filesystem lookup for firmware fails to find
|
||||
the requested firmware a sysfs fallback loading facility is made
|
||||
available and userspace is informed about this through uevents.
|
||||
The uevent can be suppressed if the driver explicitly requested it,
|
||||
this is known as the driver using the custom fallback mechanism.
|
||||
If the custom fallback mechanism is used userspace must always
|
||||
acknowledge failure to find firmware as the timeout for the fallback
|
||||
mechanism is disabled, and failed requests will linger forever.
|
||||
|
||||
This used to be the default firmware loading facility, and udev used
|
||||
to listen for uvents to load firmware for the kernel. The firmware
|
||||
loading facility functionality in udev has been removed, as such it
|
||||
can no longer be relied upon as a fallback mechanism. Linux no longer
|
||||
relies on or uses a fallback mechanism in userspace. If you need to
|
||||
rely on one refer to the permissively licensed firmwared:
|
||||
|
||||
https://github.com/teg/firmwared
|
||||
|
||||
Since this was the default firmware loading facility at one point,
|
||||
old userspace may exist which relies upon it, and as such this
|
||||
mechanism can never be removed from the kernel.
|
||||
|
||||
You should only enable this functionality if you are certain you
|
||||
require a fallback mechanism and have a userspace mechanism ready to
|
||||
load firmware in case it is not found. One main reason for this may
|
||||
be if you have drivers which require firmware built-in and for
|
||||
whatever reason cannot place the required firmware in initramfs.
|
||||
Another reason kernels may have this feature enabled is to support a
|
||||
driver which explicitly relies on this fallback mechanism. Only two
|
||||
drivers need this today:
|
||||
|
||||
o CONFIG_LEDS_LP55XX_COMMON
|
||||
o CONFIG_DELL_RBU
|
||||
|
||||
Outside of supporting the above drivers, another reason for needing
|
||||
this may be that your firmware resides outside of the paths the kernel
|
||||
looks for and cannot possibly be specified using the firmware_class
|
||||
path module parameter or kernel firmware_class path boot parameter
|
||||
if firmware_class is built-in.
|
||||
|
||||
A modern use case may be to temporarily mount a custom partition
|
||||
during provisioning which is only accessible to userspace, and then
|
||||
to use it to look for and fetch the required firmware. Such type of
|
||||
driver functionality may not even ever be desirable upstream by
|
||||
vendors, and as such is only required to be supported as an interface
|
||||
for provisioning. Since udev's firmware loading facility has been
|
||||
removed you can use firmwared or a fork of it to customize how you
|
||||
want to load firmware based on uevents issued.
|
||||
|
||||
Enabling this option will increase your kernel image size by about
|
||||
13436 bytes.
|
||||
|
||||
If you are unsure about this, say N here, unless you are Linux
|
||||
distribution and need to support the above two drivers, or you are
|
||||
certain you need to support some really custom firmware loading
|
||||
facility in userspace.
|
||||
|
||||
config FW_LOADER_USER_HELPER_FALLBACK
|
||||
bool "Force the firmware sysfs fallback mechanism when possible"
|
||||
depends on FW_LOADER_USER_HELPER
|
||||
help
|
||||
Enabling this option forces a sysfs userspace fallback mechanism
|
||||
to be used for all firmware requests which explicitly do not disable a
|
||||
a fallback mechanism. Firmware calls which do prohibit a fallback
|
||||
mechanism is request_firmware_direct(). This option is kept for
|
||||
backward compatibility purposes given this precise mechanism can also
|
||||
be enabled by setting the proc sysctl value to true:
|
||||
|
||||
/proc/sys/kernel/firmware_config/force_sysfs_fallback
|
||||
|
||||
If you are unsure about this, say N here.
|
||||
|
||||
endif # FW_LOADER
|
||||
endmenu
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||||
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