350 lines
12 KiB
Plaintext
350 lines
12 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0
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menu "Generic Driver Options"
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config UEVENT_HELPER
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bool "Support for uevent helper"
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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
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used to hook hotplug scripts into kernel device events. It
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usually pointed to a shell script at /sbin/hotplug.
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This should not be used today, because usual systems create
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many events at bootup or device discovery in a very short time
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frame. One forked process per event can create so many processes
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that it creates a high system load, or on smaller systems
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it is known to create out-of-memory situations during bootup.
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config UEVENT_HELPER_PATH
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string "path to uevent helper"
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depends on UEVENT_HELPER
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default ""
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help
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To disable user space helper program execution at by default
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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
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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
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nodes with their default names and permissions for all
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registered devices with an assigned major/minor number.
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Userspace can modify the filesystem content as needed, add
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symlinks, and apply needed permissions.
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It provides a fully functional /dev directory, where usually
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udev runs on top, managing permissions and adding meaningful
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symlinks.
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In very limited environments, it may provide a sufficient
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functional /dev without any further help. It also allows simple
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rescue systems, and reliably handles dynamic major/minor numbers.
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Notice: if CONFIG_TMPFS isn't enabled, the simpler ramfs
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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
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help
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This will instruct the kernel to automatically mount the
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devtmpfs filesystem at /dev, directly after the kernel has
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mounted the root filesystem. The behavior can be overridden
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with the commandline parameter: devtmpfs.mount=0|1.
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This option does not affect initramfs based booting, here
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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
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rescue mode with init=/bin/sh, even when the /dev directory
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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
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help
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Select this option if you don't have magic firmware for drivers that
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need it.
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If unsure, say Y.
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config PREVENT_FIRMWARE_BUILD
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bool "Prevent firmware from being built"
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default y
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help
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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
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rebuild be made.
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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
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require userspace firmware loading support, but a module built
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out-of-tree does.
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config FIRMWARE_IN_KERNEL
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bool "Include in-kernel firmware blobs in kernel binary"
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depends on FW_LOADER
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default y
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help
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Various drivers in the kernel source tree may require firmware,
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which is generally available in your distribution's linux-firmware
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package.
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The linux-firmware package should install firmware into
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/lib/firmware/ on your system, so they can be loaded by userspace
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helpers on request.
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Enabling this option will build each required firmware blob
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specified by EXTRA_FIRMWARE into the kernel directly, where
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request_firmware() will find them without having to call out to
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userspace. This may be useful if your root file system requires a
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device that uses such firmware and you do not wish to use an
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initrd.
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This single option controls the inclusion of firmware for
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every driver that uses request_firmware(), which avoids a
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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
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string "External firmware blobs to build into the kernel binary"
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depends on FW_LOADER
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help
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This option allows firmware to be built into the kernel for the case
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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
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required for accessing the boot device, and the user doesn't want to
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use an initrd).
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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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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
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the usb8388.bin file into the firmware directory, and build the kernel.
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Then any request_firmware("usb8388.bin") will be satisfied internally
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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.
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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
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config FW_LOADER_USER_HELPER_FALLBACK
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bool "Fallback user-helper invocation for firmware loading"
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depends on FW_LOADER
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select FW_LOADER_USER_HELPER
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help
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This option enables / disables the invocation of user-helper
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(e.g. udev) for loading firmware files as a fallback after the
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direct file loading in kernel fails. The user-mode helper is
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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
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been deprecated upstream.
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If you are unsure about this, say N here.
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config WANT_DEV_COREDUMP
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bool
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help
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Drivers should "select" this option if they desire to use the
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device coredump mechanism.
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config ALLOW_DEV_COREDUMP
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bool "Allow device coredump" if EXPERT
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default y
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help
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This option controls if the device coredump mechanism is available or
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not; if disabled, the mechanism will be omitted even if drivers that
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can use it are enabled.
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Say 'N' for more sensitive systems or systems that don't want
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to ever access the information to not have the code, nor keep any
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data.
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If unsure, say Y.
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config DEV_COREDUMP
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bool
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default y if WANT_DEV_COREDUMP
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depends on ALLOW_DEV_COREDUMP
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config DEBUG_DRIVER
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bool "Driver Core verbose debug messages"
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depends on DEBUG_KERNEL
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help
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Say Y here if you want the Driver core to produce a bunch of
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debug messages to the system log. Select this if you are having a
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problem with the driver core and want to see more of what is
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going on.
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If you are unsure about this, say N here.
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config DEBUG_DEVRES
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bool "Managed device resources verbose debug messages"
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depends on DEBUG_KERNEL
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help
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This option enables kernel parameter devres.log. If set to
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non-zero, devres debug messages are printed. Select this if
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you are having a problem with devres or want to debug
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resource management for a managed device. devres.log can be
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switched on and off from sysfs node.
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If you are unsure about this, Say N here.
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config DEBUG_TEST_DRIVER_REMOVE
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bool "Test driver remove calls during probe (UNSTABLE)"
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depends on DEBUG_KERNEL
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help
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Say Y here if you want the Driver core to test driver remove functions
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by calling probe, remove, probe. This tests the remove path without
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having to unbind the driver or unload the driver module.
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This option is expected to find errors and may render your system
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unusable. You should say N here unless you are explicitly looking to
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test this functionality.
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source "drivers/base/test/Kconfig"
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config SYS_HYPERVISOR
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bool
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default n
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config GENERIC_CPU_DEVICES
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bool
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default n
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config GENERIC_CPU_AUTOPROBE
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bool
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config SOC_BUS
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bool
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select GLOB
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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
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select ANON_INODES
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help
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This option enables the framework for buffer-sharing between
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multiple drivers. A buffer is associated with a file using driver
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APIs extension; the file's descriptor can then be passed on to other
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driver.
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config DMA_FENCE_TRACE
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bool "Enable verbose DMA_FENCE_TRACE messages"
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depends on DMA_SHARED_BUFFER
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help
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Enable the DMA_FENCE_TRACE printks. This will add extra
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spam to the console log, but will make it easier to diagnose
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lockup related problems for dma-buffers shared across multiple
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devices.
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config DMA_CMA
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bool "DMA Contiguous Memory Allocator"
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depends on HAVE_DMA_CONTIGUOUS && CMA
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help
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This enables the Contiguous Memory Allocator which allows drivers
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to allocate big physically-contiguous blocks of memory for use with
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hardware components that do not support I/O map nor scatter-gather.
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You can disable CMA by specifying "cma=0" on the kernel's command
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line.
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For more information see <include/linux/dma-contiguous.h>.
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If unsure, say "n".
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if DMA_CMA
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comment "Default contiguous memory area size:"
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config CMA_SIZE_MBYTES
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int "Size in Mega Bytes"
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depends on !CMA_SIZE_SEL_PERCENTAGE
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default 0 if X86
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default 16
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help
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Defines the size (in MiB) of the default memory area for Contiguous
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Memory Allocator. If the size of 0 is selected, CMA is disabled by
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default, but it can be enabled by passing cma=size[MG] to the kernel.
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config CMA_SIZE_PERCENTAGE
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int "Percentage of total memory"
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depends on !CMA_SIZE_SEL_MBYTES
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default 0 if X86
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default 10
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help
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Defines the size of the default memory area for Contiguous Memory
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Allocator as a percentage of the total memory in the system.
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If 0 percent is selected, CMA is disabled by default, but it can be
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enabled by passing cma=size[MG] to the kernel.
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choice
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prompt "Selected region size"
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default CMA_SIZE_SEL_MBYTES
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config CMA_SIZE_SEL_MBYTES
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bool "Use mega bytes value only"
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config CMA_SIZE_SEL_PERCENTAGE
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bool "Use percentage value only"
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config CMA_SIZE_SEL_MIN
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bool "Use lower value (minimum)"
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config CMA_SIZE_SEL_MAX
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bool "Use higher value (maximum)"
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endchoice
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config CMA_ALIGNMENT
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int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
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range 4 12
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default 8
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help
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DMA mapping framework by default aligns all buffers to the smallest
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PAGE_SIZE order which is greater than or equal to the requested buffer
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size. This works well for buffers up to a few hundreds kilobytes, but
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for larger buffers it just a memory waste. With this parameter you can
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specify the maximum PAGE_SIZE order for contiguous buffers. Larger
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buffers will be aligned only to this specified order. The order is
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expressed as a power of two multiplied by the PAGE_SIZE.
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For example, if your system defaults to 4KiB pages, the order value
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of 8 means that the buffers will be aligned up to 1MiB only.
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If unsure, leave the default value "8".
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endif
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config GENERIC_ARCH_TOPOLOGY
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bool
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help
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Enable support for architectures common topology code: e.g., parsing
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CPU capacity information from DT, usage of such information for
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appropriate scaling, sysfs interface for changing capacity values at
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runtime.
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endmenu
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