drivers/base/Kconfig

   1 menu "Generic Driver Options"
   2
   3 config UEVENT_HELPER
   4         bool "Support for uevent helper"
   5         default y
   6         help
   7           The uevent helper program is forked by the kernel for
   8           every uevent.
   9           Before the switch to the netlink-based uevent source, this was
  10           used to hook hotplug scripts into kernel device events. It
  11           usually pointed to a shell script at /sbin/hotplug.
  12           This should not be used today, because usual systems create
  13           many events at bootup or device discovery in a very short time
  14           frame. One forked process per event can create so many processes
  15           that it creates a high system load, or on smaller systems
  16           it is known to create out-of-memory situations during bootup.
  17
  18 config UEVENT_HELPER_PATH
  19         string "path to uevent helper"
  20         depends on UEVENT_HELPER
  21         default ""
  22         help
  23           To disable user space helper program execution at by default
  24           specify an empty string here. This setting can still be altered
  25           via /proc/sys/kernel/hotplug or via /sys/kernel/uevent_helper
  26           later at runtime.
  27
  28 config DEVTMPFS
  29         bool "Maintain a devtmpfs filesystem to mount at /dev"
  30         help
  31           This creates a tmpfs/ramfs filesystem instance early at bootup.
  32           In this filesystem, the kernel driver core maintains device
  33           nodes with their default names and permissions for all
  34           registered devices with an assigned major/minor number.
  35           Userspace can modify the filesystem content as needed, add
  36           symlinks, and apply needed permissions.
  37           It provides a fully functional /dev directory, where usually
  38           udev runs on top, managing permissions and adding meaningful
  39           symlinks.
  40           In very limited environments, it may provide a sufficient
  41           functional /dev without any further help. It also allows simple
  42           rescue systems, and reliably handles dynamic major/minor numbers.
  43
  44           Notice: if CONFIG_TMPFS isn't enabled, the simpler ramfs
  45           file system will be used instead.
  46
  47 config DEVTMPFS_MOUNT
  48         bool "Automount devtmpfs at /dev, after the kernel mounted the rootfs"
  49         depends on DEVTMPFS
  50         help
  51           This will instruct the kernel to automatically mount the
  52           devtmpfs filesystem at /dev, directly after the kernel has
  53           mounted the root filesystem. The behavior can be overridden
  54           with the commandline parameter: devtmpfs.mount=0|1.
  55           This option does not affect initramfs based booting, here
  56           the devtmpfs filesystem always needs to be mounted manually
  57           after the rootfs is mounted.
  58           With this option enabled, it allows to bring up a system in
  59           rescue mode with init=/bin/sh, even when the /dev directory
  60           on the rootfs is completely empty.
  61
  62 config STANDALONE
  63         bool "Select only drivers that don't need compile-time external firmware"
  64         default y
  65         help
  66           Select this option if you don't have magic firmware for drivers that
  67           need it.
  68
  69           If unsure, say Y.
  70
  71 config PREVENT_FIRMWARE_BUILD
  72         bool "Prevent firmware from being built"
  73         default y
  74         help
  75           Say yes to avoid building firmware. Firmware is usually shipped
  76           with the driver and only when updating the firmware should a
  77           rebuild be made.
  78           If unsure, say Y here.
  79
  80 config FW_LOADER
  81         tristate "Userspace firmware loading support" if EXPERT
  82         default y
  83         ---help---
  84           This option is provided for the case where none of the in-tree modules
  85           require userspace firmware loading support, but a module built
  86           out-of-tree does.
  87
  88 config FIRMWARE_IN_KERNEL
  89         bool "Include in-kernel firmware blobs in kernel binary"
  90         depends on FW_LOADER
  91         default y
  92         help
  93           The kernel source tree includes a number of firmware 'blobs'
  94           that are used by various drivers. The recommended way to
  95           use these is to run "make firmware_install", which, after
  96           converting ihex files to binary, copies all of the needed
  97           binary files in firmware/ to /lib/firmware/ on your system so
  98           that they can be loaded by userspace helpers on request.
  99
 100           Enabling this option will build each required firmware blob
 101           into the kernel directly, where request_firmware() will find
 102           them without having to call out to userspace. This may be
 103           useful if your root file system requires a device that uses
 104           such firmware and do not wish to use an initrd.
 105
 106           This single option controls the inclusion of firmware for
 107           every driver that uses request_firmware() and ships its
 108           firmware in the kernel source tree, which avoids a
 109           proliferation of 'Include firmware for xxx device' options.
 110
 111           Say 'N' and let firmware be loaded from userspace.
 112
 113 config EXTRA_FIRMWARE
 114         string "External firmware blobs to build into the kernel binary"
 115         depends on FW_LOADER
 116         help
 117           This option allows firmware to be built into the kernel for the case
 118           where the user either cannot or doesn't want to provide it from
 119           userspace at runtime (for example, when the firmware in question is
 120           required for accessing the boot device, and the user doesn't want to
 121           use an initrd).
 122
 123           This option is a string and takes the (space-separated) names of the
 124           firmware files -- the same names that appear in MODULE_FIRMWARE()
 125           and request_firmware() in the source. These files should exist under
 126           the directory specified by the EXTRA_FIRMWARE_DIR option, which is
 127           by default the firmware subdirectory of the kernel source tree.
 128
 129           For example, you might set CONFIG_EXTRA_FIRMWARE="usb8388.bin", copy
 130           the usb8388.bin file into the firmware directory, and build the kernel.
 131           Then any request_firmware("usb8388.bin") will be satisfied internally
 132           without needing to call out to userspace.
 133
 134           WARNING: If you include additional firmware files into your binary
 135           kernel image that are not available under the terms of the GPL,
 136           then it may be a violation of the GPL to distribute the resulting
 137           image since it combines both GPL and non-GPL work. You should
 138           consult a lawyer of your own before distributing such an image.
 139
 140 config EXTRA_FIRMWARE_DIR
 141         string "Firmware blobs root directory"
 142         depends on EXTRA_FIRMWARE != ""
 143         default "firmware"
 144         help
 145           This option controls the directory in which the kernel build system
 146           looks for the firmware files listed in the EXTRA_FIRMWARE option.
 147           The default is firmware/ in the kernel source tree, but by changing
 148           this option you can point it elsewhere, such as /lib/firmware/ or
 149           some other directory containing the firmware files.
 150
 151 config FW_LOADER_USER_HELPER
 152         bool
 153
 154 config FW_LOADER_USER_HELPER_FALLBACK
 155         bool "Fallback user-helper invocation for firmware loading"
 156         depends on FW_LOADER
 157         select FW_LOADER_USER_HELPER
 158         help
 159           This option enables / disables the invocation of user-helper
 160           (e.g. udev) for loading firmware files as a fallback after the
 161           direct file loading in kernel fails.  The user-mode helper is
 162           no longer required unless you have a special firmware file that
 163           resides in a non-standard path. Moreover, the udev support has
 164           been deprecated upstream.
 165
 166           If you are unsure about this, say N here.
 167
 168 config WANT_DEV_COREDUMP
 169         bool
 170         help
 171           Drivers should "select" this option if they desire to use the
 172           device coredump mechanism.
 173
 174 config ALLOW_DEV_COREDUMP
 175         bool "Allow device coredump" if EXPERT
 176         default y
 177         help
 178           This option controls if the device coredump mechanism is available or
 179           not; if disabled, the mechanism will be omitted even if drivers that
 180           can use it are enabled.
 181           Say 'N' for more sensitive systems or systems that don't want
 182           to ever access the information to not have the code, nor keep any
 183           data.
 184
 185           If unsure, say Y.
 186
 187 config DEV_COREDUMP
 188         bool
 189         default y if WANT_DEV_COREDUMP
 190         depends on ALLOW_DEV_COREDUMP
 191
 192 config DEBUG_DRIVER
 193         bool "Driver Core verbose debug messages"
 194         depends on DEBUG_KERNEL
 195         help
 196           Say Y here if you want the Driver core to produce a bunch of
 197           debug messages to the system log. Select this if you are having a
 198           problem with the driver core and want to see more of what is
 199           going on.
 200
 201           If you are unsure about this, say N here.
 202
 203 config DEBUG_DEVRES
 204         bool "Managed device resources verbose debug messages"
 205         depends on DEBUG_KERNEL
 206         help
 207           This option enables kernel parameter devres.log. If set to
 208           non-zero, devres debug messages are printed. Select this if
 209           you are having a problem with devres or want to debug
 210           resource management for a managed device. devres.log can be
 211           switched on and off from sysfs node.
 212
 213           If you are unsure about this, Say N here.
 214
 215 config DEBUG_TEST_DRIVER_REMOVE
 216         bool "Test driver remove calls during probe (UNSTABLE)"
 217         depends on DEBUG_KERNEL
 218         help
 219           Say Y here if you want the Driver core to test driver remove functions
 220           by calling probe, remove, probe. This tests the remove path without
 221           having to unbind the driver or unload the driver module.
 222
 223           This option is expected to find errors and may render your system
 224           unusable. You should say N here unless you are explicitly looking to
 225           test this functionality.
 226
 227 source "drivers/base/test/Kconfig"
 228
 229 config SYS_HYPERVISOR
 230         bool
 231         default n
 232
 233 config GENERIC_CPU_DEVICES
 234         bool
 235         default n
 236
 237 config GENERIC_CPU_AUTOPROBE
 238         bool
 239
 240 config GENERIC_CPU_VULNERABILITIES
 241         bool
 242
 243 config SOC_BUS
 244         bool
 245         select GLOB
 246
 247 source "drivers/base/regmap/Kconfig"
 248
 249 config DMA_SHARED_BUFFER
 250         bool
 251         default n
 252         select ANON_INODES
 253         help
 254           This option enables the framework for buffer-sharing between
 255           multiple drivers. A buffer is associated with a file using driver
 256           APIs extension; the file's descriptor can then be passed on to other
 257           driver.
 258
 259 config DMA_FENCE_TRACE
 260         bool "Enable verbose DMA_FENCE_TRACE messages"
 261         depends on DMA_SHARED_BUFFER
 262         help
 263           Enable the DMA_FENCE_TRACE printks. This will add extra
 264           spam to the console log, but will make it easier to diagnose
 265           lockup related problems for dma-buffers shared across multiple
 266           devices.
 267
 268 config DMA_CMA
 269         bool "DMA Contiguous Memory Allocator"
 270         depends on HAVE_DMA_CONTIGUOUS && CMA
 271         help
 272           This enables the Contiguous Memory Allocator which allows drivers
 273           to allocate big physically-contiguous blocks of memory for use with
 274           hardware components that do not support I/O map nor scatter-gather.
 275
 276           You can disable CMA by specifying "cma=0" on the kernel's command
 277           line.
 278
 279           For more information see <include/linux/dma-contiguous.h>.
 280           If unsure, say "n".
 281
 282 if  DMA_CMA
 283 comment "Default contiguous memory area size:"
 284
 285 config CMA_SIZE_MBYTES
 286         int "Size in Mega Bytes"
 287         depends on !CMA_SIZE_SEL_PERCENTAGE
 288         default 0 if X86
 289         default 16
 290         help
 291           Defines the size (in MiB) of the default memory area for Contiguous
 292           Memory Allocator.  If the size of 0 is selected, CMA is disabled by
 293           default, but it can be enabled by passing cma=size[MG] to the kernel.
 294
 295
 296 config CMA_SIZE_PERCENTAGE
 297         int "Percentage of total memory"
 298         depends on !CMA_SIZE_SEL_MBYTES
 299         default 0 if X86
 300         default 10
 301         help
 302           Defines the size of the default memory area for Contiguous Memory
 303           Allocator as a percentage of the total memory in the system.
 304           If 0 percent is selected, CMA is disabled by default, but it can be
 305           enabled by passing cma=size[MG] to the kernel.
 306
 307 choice
 308         prompt "Selected region size"
 309         default CMA_SIZE_SEL_MBYTES
 310
 311 config CMA_SIZE_SEL_MBYTES
 312         bool "Use mega bytes value only"
 313
 314 config CMA_SIZE_SEL_PERCENTAGE
 315         bool "Use percentage value only"
 316
 317 config CMA_SIZE_SEL_MIN
 318         bool "Use lower value (minimum)"
 319
 320 config CMA_SIZE_SEL_MAX
 321         bool "Use higher value (maximum)"
 322
 323 endchoice
 324
 325 config CMA_ALIGNMENT
 326         int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
 327         range 4 12
 328         default 8
 329         help
 330           DMA mapping framework by default aligns all buffers to the smallest
 331           PAGE_SIZE order which is greater than or equal to the requested buffer
 332           size. This works well for buffers up to a few hundreds kilobytes, but
 333           for larger buffers it just a memory waste. With this parameter you can
 334           specify the maximum PAGE_SIZE order for contiguous buffers. Larger
 335           buffers will be aligned only to this specified order. The order is
 336           expressed as a power of two multiplied by the PAGE_SIZE.
 337
 338           For example, if your system defaults to 4KiB pages, the order value
 339           of 8 means that the buffers will be aligned up to 1MiB only.
 340
 341           If unsure, leave the default value "8".
 342
 343 endif
 344
 345 config GENERIC_ARCH_TOPOLOGY
 346         bool
 347         help
 348           Enable support for architectures common topology code: e.g., parsing
 349           CPU capacity information from DT, usage of such information for
 350           appropriate scaling, sysfs interface for changing capacity values at
 351           runtime.
 352
 353 endmenu