drivers/base/Kconfig - linux - Git at Google

 # SPDX-License-Identifier: GPL-2.0
 menu "Generic Driver Options"

 config AUXILIARY_BUS
 	bool

 config UEVENT_HELPER
 	bool "Support for uevent helper"
 	help
 	  The uevent helper program is forked by the kernel for
 	  every uevent.
 	  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.

 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
 	  via /proc/sys/kernel/hotplug or via /sys/kernel/uevent_helper
 	  later at runtime.

 config DEVTMPFS
 	bool "Maintain a devtmpfs filesystem to mount at /dev"
 	help
 	  This creates a tmpfs/ramfs filesystem instance early at bootup.
 	  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.

 	  Notice: if CONFIG_TMPFS isn't enabled, the simpler ramfs
 	  file system will be used instead.

 config DEVTMPFS_MOUNT
 	bool "Automount devtmpfs at /dev, after the kernel mounted the rootfs"
 	depends on DEVTMPFS
 	help
 	  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
 	  after the rootfs is mounted.
 	  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.

 config DEVTMPFS_SAFE
 	bool "Use nosuid,noexec mount options on devtmpfs"
 	depends on DEVTMPFS
 	help
 	  This instructs the kernel to include the MS_NOEXEC and MS_NOSUID mount
 	  flags when mounting devtmpfs.

 	  Notice: If enabled, things like /dev/mem cannot be mmapped
 	  with the PROT_EXEC flag. This can break, for example, non-KMS
 	  video drivers.

 config STANDALONE
 	bool "Select only drivers that don't need compile-time external firmware"
 	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 "Disable drivers features which enable custom firmware building"
 	default y
 	help
 	  Say yes to disable driver features which enable building a custom
 	  driver firmware at kernel build time. These drivers do not use the
 	  kernel firmware API to load firmware (CONFIG_FW_LOADER), instead they
 	  use their own custom loading mechanism. The required firmware is
 	  usually shipped with the driver, building the driver firmware
 	  should only be needed if you have an updated firmware source.

 	  Firmware should not be being built as part of kernel, these days
 	  you should always prevent this and say Y here. There are only two
 	  old drivers which enable building of its firmware at kernel build
 	  time:

 	    o CONFIG_WANXL through CONFIG_WANXL_BUILD_FIRMWARE
 	    o CONFIG_SCSI_AIC79XX through CONFIG_AIC79XX_BUILD_FIRMWARE

 source "drivers/base/firmware_loader/Kconfig"

 config WANT_DEV_COREDUMP
 	bool
 	help
 	  Drivers should "select" this option if they desire to use the
 	  device coredump mechanism.

 config ALLOW_DEV_COREDUMP
 	bool "Allow device coredump" if EXPERT
 	default y
 	help
 	  This option controls if the device coredump mechanism is available or
 	  not; if disabled, the mechanism will be omitted even if drivers that
 	  can use it are enabled.
 	  Say 'N' for more sensitive systems or systems that don't want
 	  to ever access the information to not have the code, nor keep any
 	  data.

 	  If unsure, say Y.

 config DEV_COREDUMP
 	bool
 	default y if WANT_DEV_COREDUMP
 	depends on ALLOW_DEV_COREDUMP

 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.

 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.

 config DEBUG_TEST_DRIVER_REMOVE
 	bool "Test driver remove calls during probe (UNSTABLE)"
 	depends on DEBUG_KERNEL
 	help
 	  Say Y here if you want the Driver core to test driver remove functions
 	  by calling probe, remove, probe. This tests the remove path without
 	  having to unbind the driver or unload the driver module.

 	  This option is expected to find errors and may render your system
 	  unusable. You should say N here unless you are explicitly looking to
 	  test this functionality.

 config PM_QOS_KUNIT_TEST
 	bool "KUnit Test for PM QoS features" if !KUNIT_ALL_TESTS
 	depends on KUNIT=y
 	default KUNIT_ALL_TESTS

 config HMEM_REPORTING
 	bool
 	default n
 	depends on NUMA
 	help
 	  Enable reporting for heterogeneous memory access attributes under
 	  their non-uniform memory nodes.

 source "drivers/base/test/Kconfig"

 config SYS_HYPERVISOR
 	bool
 	default n

 config GENERIC_CPU_DEVICES
 	bool
 	default n

 config GENERIC_CPU_AUTOPROBE
 	bool

 config GENERIC_CPU_VULNERABILITIES
 	bool

 config SOC_BUS
 	bool
 	select GLOB

 source "drivers/base/regmap/Kconfig"

 config DMA_SHARED_BUFFER
 	bool
 	default n
 	select IRQ_WORK
 	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.

 config DMA_FENCE_TRACE
 	bool "Enable verbose DMA_FENCE_TRACE messages"
 	depends on DMA_SHARED_BUFFER
 	help
 	  Enable the DMA_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.

 config GENERIC_ARCH_TOPOLOGY
 	bool
 	help
 	  Enable support for architectures common topology code: e.g., parsing
 	  CPU capacity information from DT, usage of such information for
 	  appropriate scaling, sysfs interface for reading capacity values at
 	  runtime.

 config GENERIC_ARCH_NUMA
 	bool
 	help
 	  Enable support for generic NUMA implementation. Currently, RISC-V
 	  and ARM64 use it.

 config FW_DEVLINK_SYNC_STATE_TIMEOUT
 	bool "sync_state() behavior defaults to timeout instead of strict"
 	help
 	  This is build time equivalent of adding kernel command line parameter
 	  "fw_devlink.sync_state=timeout". Give up waiting on consumers and
 	  call sync_state() on any devices that haven't yet received their
 	  sync_state() calls after deferred_probe_timeout has expired or by
 	  late_initcall() if !CONFIG_MODULES. You should almost always want to
 	  select N here unless you have already successfully tested with the
 	  command line option on every system/board your kernel is expected to
 	  work on.

 endmenu
	# SPDX-License-Identifier: GPL-2.0
	menu "Generic Driver Options"

	config AUXILIARY_BUS
	bool

	config UEVENT_HELPER
	bool "Support for uevent helper"
	help
	The uevent helper program is forked by the kernel for
	every uevent.
	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.

	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
	via /proc/sys/kernel/hotplug or via /sys/kernel/uevent_helper
	later at runtime.

	config DEVTMPFS
	bool "Maintain a devtmpfs filesystem to mount at /dev"
	help
	This creates a tmpfs/ramfs filesystem instance early at bootup.
	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.

	Notice: if CONFIG_TMPFS isn't enabled, the simpler ramfs
	file system will be used instead.

	config DEVTMPFS_MOUNT
	bool "Automount devtmpfs at /dev, after the kernel mounted the rootfs"
	depends on DEVTMPFS
	help
	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
	after the rootfs is mounted.
	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.

	config DEVTMPFS_SAFE
	bool "Use nosuid,noexec mount options on devtmpfs"
	depends on DEVTMPFS
	help
	This instructs the kernel to include the MS_NOEXEC and MS_NOSUID mount
	flags when mounting devtmpfs.

	Notice: If enabled, things like /dev/mem cannot be mmapped
	with the PROT_EXEC flag. This can break, for example, non-KMS
	video drivers.

	config STANDALONE
	bool "Select only drivers that don't need compile-time external firmware"
	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 "Disable drivers features which enable custom firmware building"
	default y
	help
	Say yes to disable driver features which enable building a custom
	driver firmware at kernel build time. These drivers do not use the
	kernel firmware API to load firmware (CONFIG_FW_LOADER), instead they
	use their own custom loading mechanism. The required firmware is
	usually shipped with the driver, building the driver firmware
	should only be needed if you have an updated firmware source.

	Firmware should not be being built as part of kernel, these days
	you should always prevent this and say Y here. There are only two
	old drivers which enable building of its firmware at kernel build
	time:

	o CONFIG_WANXL through CONFIG_WANXL_BUILD_FIRMWARE
	o CONFIG_SCSI_AIC79XX through CONFIG_AIC79XX_BUILD_FIRMWARE

	source "drivers/base/firmware_loader/Kconfig"

	config WANT_DEV_COREDUMP
	bool
	help
	Drivers should "select" this option if they desire to use the
	device coredump mechanism.

	config ALLOW_DEV_COREDUMP
	bool "Allow device coredump" if EXPERT
	default y
	help
	This option controls if the device coredump mechanism is available or
	not; if disabled, the mechanism will be omitted even if drivers that
	can use it are enabled.
	Say 'N' for more sensitive systems or systems that don't want
	to ever access the information to not have the code, nor keep any
	data.

	If unsure, say Y.

	config DEV_COREDUMP
	bool
	default y if WANT_DEV_COREDUMP
	depends on ALLOW_DEV_COREDUMP

	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.

	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.

	config DEBUG_TEST_DRIVER_REMOVE
	bool "Test driver remove calls during probe (UNSTABLE)"
	depends on DEBUG_KERNEL
	help
	Say Y here if you want the Driver core to test driver remove functions
	by calling probe, remove, probe. This tests the remove path without
	having to unbind the driver or unload the driver module.

	This option is expected to find errors and may render your system
	unusable. You should say N here unless you are explicitly looking to
	test this functionality.

	config PM_QOS_KUNIT_TEST
	bool "KUnit Test for PM QoS features" if !KUNIT_ALL_TESTS
	depends on KUNIT=y
	default KUNIT_ALL_TESTS

	config HMEM_REPORTING
	bool
	default n
	depends on NUMA
	help
	Enable reporting for heterogeneous memory access attributes under
	their non-uniform memory nodes.

	source "drivers/base/test/Kconfig"

	config SYS_HYPERVISOR
	bool
	default n

	config GENERIC_CPU_DEVICES
	bool
	default n

	config GENERIC_CPU_AUTOPROBE
	bool

	config GENERIC_CPU_VULNERABILITIES
	bool

	config SOC_BUS
	bool
	select GLOB

	source "drivers/base/regmap/Kconfig"

	config DMA_SHARED_BUFFER
	bool
	default n
	select IRQ_WORK
	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.

	config DMA_FENCE_TRACE
	bool "Enable verbose DMA_FENCE_TRACE messages"
	depends on DMA_SHARED_BUFFER
	help
	Enable the DMA_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.

	config GENERIC_ARCH_TOPOLOGY
	bool
	help
	Enable support for architectures common topology code: e.g., parsing
	CPU capacity information from DT, usage of such information for
	appropriate scaling, sysfs interface for reading capacity values at
	runtime.

	config GENERIC_ARCH_NUMA
	bool
	help
	Enable support for generic NUMA implementation. Currently, RISC-V
	and ARM64 use it.

	config FW_DEVLINK_SYNC_STATE_TIMEOUT
	bool "sync_state() behavior defaults to timeout instead of strict"
	help
	This is build time equivalent of adding kernel command line parameter
	"fw_devlink.sync_state=timeout". Give up waiting on consumers and
	call sync_state() on any devices that haven't yet received their
	sync_state() calls after deferred_probe_timeout has expired or by
	late_initcall() if !CONFIG_MODULES. You should almost always want to
	select N here unless you have already successfully tested with the
	command line option on every system/board your kernel is expected to
	work on.

	endmenu