xref: /openbmc/linux/drivers/base/Kconfig (revision 7934779a)

menu "Generic Driver Options"

config UEVENT_HELPER_PATH
	string "path to uevent helper"
	depends on HOTPLUG
	default ""
	help
	  Path to uevent helper program 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 DEVTMPFS
	bool "Maintain a devtmpfs filesystem to mount at /dev"
	depends on HOTPLUG && SHMEM && TMPFS
	help
	  This creates a tmpfs 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.

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 roots 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 STANDALONE
	bool "Select only drivers that don't need compile-time external firmware" if EXPERIMENTAL
	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
	  with the driver, and only when updating the firmware a rebuild
	  should be made.
	  If unsure say Y here.

config FW_LOADER
	tristate "Userspace firmware loading support" if EMBEDDED
	depends on HOTPLUG
	default y
	---help---
	  This option is provided for the case where no in-kernel-tree modules
	  require userspace firmware loading support, but a module built outside
	  the kernel tree does.

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'
	  which are used by various drivers. The recommended way to
	  use these is to run "make firmware_install" and to copy the
	  resulting binary files created in usr/lib/firmware directory
	  of the kernel tree to the /lib/firmware on your system so
	  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
	  useful if your root file system requires a device which uses
	  such firmware, and do not wish to use an initrd.

	  This single option controls the inclusion of firmware for
	  every driver which uses request_firmware() and ships its
	  firmware in the kernel source tree, to avoid a proliferation
	  of 'Include firmware for xxx device' options.

	  Say 'N' and let firmware be loaded from userspace.

config EXTRA_FIRMWARE
	string "External firmware blobs to build into the kernel binary"
	depends on FW_LOADER
	help
	  This option allows firmware to be built into the kernel, for the
	  cases where the user either cannot or doesn't want to provide it from
	  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).

	  This option is a string, and takes the (space-separated) names of the
	  firmware files -- the same names which 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
	  by default the firmware/ subdirectory of the kernel source tree.

	  So, 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.

	  WARNING: If you include additional firmware files into your binary
	  kernel image which 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
	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.
	  The default is the firmware/ directory in the kernel source tree,
	  but by changing this option you can point it elsewhere, such as
	  the /lib/firmware/ directory or another separate directory
	  containing firmware files.

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 SYS_HYPERVISOR
	bool
	default n

endmenu