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 DISABLE_DEV_COREDUMP
 175         bool "Disable device coredump" if EXPERT
 176         help
 177           Disable the device coredump mechanism despite drivers wanting to
 178           use it; this allows for more sensitive systems or systems that
 179           don't want to ever access the information to not have the code,
 180           nor keep any data.
 181
 182           If unsure, say N.
 183
 184 config DEV_COREDUMP
 185         bool
 186         default y if WANT_DEV_COREDUMP
 187         depends on !DISABLE_DEV_COREDUMP
 188
 189 config DEBUG_DRIVER
 190         bool "Driver Core verbose debug messages"
 191         depends on DEBUG_KERNEL
 192         help
 193           Say Y here if you want the Driver core to produce a bunch of
 194           debug messages to the system log. Select this if you are having a
 195           problem with the driver core and want to see more of what is
 196           going on.
 197
 198           If you are unsure about this, say N here.
 199
 200 config DEBUG_DEVRES
 201         bool "Managed device resources verbose debug messages"
 202         depends on DEBUG_KERNEL
 203         help
 204           This option enables kernel parameter devres.log. If set to
 205           non-zero, devres debug messages are printed. Select this if
 206           you are having a problem with devres or want to debug
 207           resource management for a managed device. devres.log can be
 208           switched on and off from sysfs node.
 209
 210           If you are unsure about this, Say N here.
 211
 212 config SYS_HYPERVISOR
 213         bool
 214         default n
 215
 216 config GENERIC_CPU_DEVICES
 217         bool
 218         default n
 219
 220 config GENERIC_CPU_AUTOPROBE
 221         bool
 222
 223 config SOC_BUS
 224         bool
 225
 226 source "drivers/base/regmap/Kconfig"
 227
 228 config DMA_SHARED_BUFFER
 229         bool
 230         default n
 231         select ANON_INODES
 232         help
 233           This option enables the framework for buffer-sharing between
 234           multiple drivers. A buffer is associated with a file using driver
 235           APIs extension; the file's descriptor can then be passed on to other
 236           driver.
 237
 238 config FENCE_TRACE
 239         bool "Enable verbose FENCE_TRACE messages"
 240         depends on DMA_SHARED_BUFFER
 241         help
 242           Enable the FENCE_TRACE printks. This will add extra
 243           spam to the console log, but will make it easier to diagnose
 244           lockup related problems for dma-buffers shared across multiple
 245           devices.
 246
 247 config DMA_CMA
 248         bool "DMA Contiguous Memory Allocator"
 249         depends on HAVE_DMA_CONTIGUOUS && CMA
 250         help
 251           This enables the Contiguous Memory Allocator which allows drivers
 252           to allocate big physically-contiguous blocks of memory for use with
 253           hardware components that do not support I/O map nor scatter-gather.
 254
 255           You can disable CMA by specifying "cma=0" on the kernel's command
 256           line.
 257
 258           For more information see <include/linux/dma-contiguous.h>.
 259           If unsure, say "n".
 260
 261 if  DMA_CMA
 262 comment "Default contiguous memory area size:"
 263
 264 config CMA_SIZE_MBYTES
 265         int "Size in Mega Bytes"
 266         depends on !CMA_SIZE_SEL_PERCENTAGE
 267         default 16
 268         help
 269           Defines the size (in MiB) of the default memory area for Contiguous
 270           Memory Allocator.
 271
 272 config CMA_SIZE_PERCENTAGE
 273         int "Percentage of total memory"
 274         depends on !CMA_SIZE_SEL_MBYTES
 275         default 10
 276         help
 277           Defines the size of the default memory area for Contiguous Memory
 278           Allocator as a percentage of the total memory in the system.
 279
 280 choice
 281         prompt "Selected region size"
 282         default CMA_SIZE_SEL_MBYTES
 283
 284 config CMA_SIZE_SEL_MBYTES
 285         bool "Use mega bytes value only"
 286
 287 config CMA_SIZE_SEL_PERCENTAGE
 288         bool "Use percentage value only"
 289
 290 config CMA_SIZE_SEL_MIN
 291         bool "Use lower value (minimum)"
 292
 293 config CMA_SIZE_SEL_MAX
 294         bool "Use higher value (maximum)"
 295
 296 endchoice
 297
 298 config CMA_ALIGNMENT
 299         int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
 300         range 4 12
 301         default 8
 302         help
 303           DMA mapping framework by default aligns all buffers to the smallest
 304           PAGE_SIZE order which is greater than or equal to the requested buffer
 305           size. This works well for buffers up to a few hundreds kilobytes, but
 306           for larger buffers it just a memory waste. With this parameter you can
 307           specify the maximum PAGE_SIZE order for contiguous buffers. Larger
 308           buffers will be aligned only to this specified order. The order is
 309           expressed as a power of two multiplied by the PAGE_SIZE.
 310
 311           For example, if your system defaults to 4KiB pages, the order value
 312           of 8 means that the buffers will be aligned up to 1MiB only.
 313
 314           If unsure, leave the default value "8".
 315
 316 endif
 317
 318 endmenu