Kconfig 10.2 KB
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menu "Generic Driver Options"

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config UEVENT_HELPER
	bool "Support for uevent helper"
	default y
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	help
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	  The uevent helper program is forked by the kernel for
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	  every uevent.
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	  Before the switch to the netlink-based uevent source, this was
	  used to hook hotplug scripts into kernel device events. It
	  usually pointed to a shell script at /sbin/hotplug.
	  This should not be used today, because usual systems create
	  many events at bootup or device discovery in a very short time
	  frame. One forked process per event can create so many processes
	  that it creates a high system load, or on smaller systems
	  it is known to create out-of-memory situations during bootup.
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config UEVENT_HELPER_PATH
	string "path to uevent helper"
	depends on UEVENT_HELPER
	default ""
	help
	  To disable user space helper program execution at by default
	  specify an empty string here. This setting can still be altered
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	  via /proc/sys/kernel/hotplug or via /sys/kernel/uevent_helper
	  later at runtime.

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config DEVTMPFS
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	bool "Maintain a devtmpfs filesystem to mount at /dev"
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	help
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	  This creates a tmpfs/ramfs filesystem instance early at bootup.
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	  In this filesystem, the kernel driver core maintains device
	  nodes with their default names and permissions for all
	  registered devices with an assigned major/minor number.
	  Userspace can modify the filesystem content as needed, add
	  symlinks, and apply needed permissions.
	  It provides a fully functional /dev directory, where usually
	  udev runs on top, managing permissions and adding meaningful
	  symlinks.
	  In very limited environments, it may provide a sufficient
	  functional /dev without any further help. It also allows simple
	  rescue systems, and reliably handles dynamic major/minor numbers.
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	  Notice: if CONFIG_TMPFS isn't enabled, the simpler ramfs
	  file system will be used instead.

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config DEVTMPFS_MOUNT
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	bool "Automount devtmpfs at /dev, after the kernel mounted the rootfs"
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	depends on DEVTMPFS
	help
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	  This will instruct the kernel to automatically mount the
	  devtmpfs filesystem at /dev, directly after the kernel has
	  mounted the root filesystem. The behavior can be overridden
	  with the commandline parameter: devtmpfs.mount=0|1.
	  This option does not affect initramfs based booting, here
	  the devtmpfs filesystem always needs to be mounted manually
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	  after the rootfs is mounted.
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	  With this option enabled, it allows to bring up a system in
	  rescue mode with init=/bin/sh, even when the /dev directory
	  on the rootfs is completely empty.
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config STANDALONE
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	bool "Select only drivers that don't need compile-time external firmware"
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	default y
	help
	  Select this option if you don't have magic firmware for drivers that
	  need it.

	  If unsure, say Y.

config PREVENT_FIRMWARE_BUILD
	bool "Prevent firmware from being built"
	default y
	help
	  Say yes to avoid building firmware. Firmware is usually shipped
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	  with the driver and only when updating the firmware should a
	  rebuild be made.
	  If unsure, say Y here.
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config FW_LOADER
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	tristate "Userspace firmware loading support" if EXPERT
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	default y
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	---help---
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	  This option is provided for the case where none of the in-tree modules
	  require userspace firmware loading support, but a module built
	  out-of-tree does.
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config FIRMWARE_IN_KERNEL
	bool "Include in-kernel firmware blobs in kernel binary"
	depends on FW_LOADER
	default y
	help
	  The kernel source tree includes a number of firmware 'blobs'
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	  that are used by various drivers. The recommended way to
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	  use these is to run "make firmware_install", which, after
	  converting ihex files to binary, copies all of the needed
	  binary files in firmware/ to /lib/firmware/ on your system so
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	  that they can be loaded by userspace helpers on request.

	  Enabling this option will build each required firmware blob
	  into the kernel directly, where request_firmware() will find
	  them without having to call out to userspace. This may be
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	  useful if your root file system requires a device that uses
	  such firmware and do not wish to use an initrd.
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	  This single option controls the inclusion of firmware for
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	  every driver that uses request_firmware() and ships its
	  firmware in the kernel source tree, which avoids a
	  proliferation of 'Include firmware for xxx device' options.
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	  Say 'N' and let firmware be loaded from userspace.

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config EXTRA_FIRMWARE
	string "External firmware blobs to build into the kernel binary"
	depends on FW_LOADER
	help
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	  This option allows firmware to be built into the kernel for the case
	  where the user either cannot or doesn't want to provide it from
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	  userspace at runtime (for example, when the firmware in question is
	  required for accessing the boot device, and the user doesn't want to
	  use an initrd).

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	  This option is a string and takes the (space-separated) names of the
	  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
	  the directory specified by the EXTRA_FIRMWARE_DIR option, which is
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	  by default the firmware subdirectory of the kernel source tree.
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	  For example, you might set CONFIG_EXTRA_FIRMWARE="usb8388.bin", copy
	  the usb8388.bin file into the firmware directory, and build the kernel.
	  Then any request_firmware("usb8388.bin") will be satisfied internally
	  without needing to call out to userspace.
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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.

config EXTRA_FIRMWARE_DIR
	string "Firmware blobs root directory"
	depends on EXTRA_FIRMWARE != ""
	default "firmware"
	help
	  This option controls the directory in which the kernel build system
	  looks for the firmware files listed in the EXTRA_FIRMWARE option.
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	  The default is firmware/ in the kernel source tree, but by changing
	  this option you can point it elsewhere, such as /lib/firmware/ or
	  some other directory containing the firmware files.
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config FW_LOADER_USER_HELPER
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	bool

config FW_LOADER_USER_HELPER_FALLBACK
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	bool "Fallback user-helper invocation for firmware loading"
	depends on FW_LOADER
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	select FW_LOADER_USER_HELPER
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	help
	  This option enables / disables the invocation of user-helper
	  (e.g. udev) for loading firmware files as a fallback after the
	  direct file loading in kernel fails.  The user-mode helper is
	  no longer required unless you have a special firmware file that
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	  resides in a non-standard path. Moreover, the udev support has
	  been deprecated upstream.

	  If you are unsure about this, say N here.
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config DEBUG_DRIVER
	bool "Driver Core verbose debug messages"
	depends on DEBUG_KERNEL
	help
	  Say Y here if you want the Driver core to produce a bunch of
	  debug messages to the system log. Select this if you are having a
	  problem with the driver core and want to see more of what is
	  going on.

	  If you are unsure about this, say N here.

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config DEBUG_DEVRES
	bool "Managed device resources verbose debug messages"
	depends on DEBUG_KERNEL
	help
	  This option enables kernel parameter devres.log. If set to
	  non-zero, devres debug messages are printed. Select this if
	  you are having a problem with devres or want to debug
	  resource management for a managed device. devres.log can be
	  switched on and off from sysfs node.

	  If you are unsure about this, Say N here.

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config SYS_HYPERVISOR
	bool
	default n
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config GENERIC_CPU_DEVICES
	bool
	default n

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config GENERIC_CPU_AUTOPROBE
	bool

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config SOC_BUS
	bool

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source "drivers/base/regmap/Kconfig"

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config DMA_SHARED_BUFFER
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	bool
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	default n
	select ANON_INODES
	help
	  This option enables the framework for buffer-sharing between
	  multiple drivers. A buffer is associated with a file using driver
	  APIs extension; the file's descriptor can then be passed on to other
	  driver.

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config FENCE_TRACE
	bool "Enable verbose FENCE_TRACE messages"
	depends on DMA_SHARED_BUFFER
	help
	  Enable the FENCE_TRACE printks. This will add extra
	  spam to the console log, but will make it easier to diagnose
	  lockup related problems for dma-buffers shared across multiple
	  devices.

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config DMA_CMA
	bool "DMA Contiguous Memory Allocator"
	depends on HAVE_DMA_CONTIGUOUS && CMA
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	help
	  This enables the Contiguous Memory Allocator which allows drivers
	  to allocate big physically-contiguous blocks of memory for use with
	  hardware components that do not support I/O map nor scatter-gather.

	  For more information see <include/linux/dma-contiguous.h>.
	  If unsure, say "n".

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if  DMA_CMA
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comment "Default contiguous memory area size:"

config CMA_SIZE_MBYTES
	int "Size in Mega Bytes"
	depends on !CMA_SIZE_SEL_PERCENTAGE
	default 16
	help
	  Defines the size (in MiB) of the default memory area for Contiguous
	  Memory Allocator.

config CMA_SIZE_PERCENTAGE
	int "Percentage of total memory"
	depends on !CMA_SIZE_SEL_MBYTES
	default 10
	help
	  Defines the size of the default memory area for Contiguous Memory
	  Allocator as a percentage of the total memory in the system.

choice
	prompt "Selected region size"
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	default CMA_SIZE_SEL_MBYTES
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config CMA_SIZE_SEL_MBYTES
	bool "Use mega bytes value only"

config CMA_SIZE_SEL_PERCENTAGE
	bool "Use percentage value only"

config CMA_SIZE_SEL_MIN
	bool "Use lower value (minimum)"

config CMA_SIZE_SEL_MAX
	bool "Use higher value (maximum)"

endchoice

config CMA_ALIGNMENT
	int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
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	range 4 12
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	default 8
	help
	  DMA mapping framework by default aligns all buffers to the smallest
	  PAGE_SIZE order which is greater than or equal to the requested buffer
	  size. This works well for buffers up to a few hundreds kilobytes, but
	  for larger buffers it just a memory waste. With this parameter you can
	  specify the maximum PAGE_SIZE order for contiguous buffers. Larger
	  buffers will be aligned only to this specified order. The order is
	  expressed as a power of two multiplied by the PAGE_SIZE.

	  For example, if your system defaults to 4KiB pages, the order value
	  of 8 means that the buffers will be aligned up to 1MiB only.

	  If unsure, leave the default value "8".

endif

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endmenu