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 "Fallback user-helper invocation for firmware loading"
 153         depends on FW_LOADER
 154         default y
 155         help
 156           This option enables / disables the invocation of user-helper
 157           (e.g. udev) for loading firmware files as a fallback after the
 158           direct file loading in kernel fails.  The user-mode helper is
 159           no longer required unless you have a special firmware file that
 160           resides in a non-standard path.
 161
 162 config DEBUG_DRIVER
 163         bool "Driver Core verbose debug messages"
 164         depends on DEBUG_KERNEL
 165         help
 166           Say Y here if you want the Driver core to produce a bunch of
 167           debug messages to the system log. Select this if you are having a
 168           problem with the driver core and want to see more of what is
 169           going on.
 170
 171           If you are unsure about this, say N here.
 172
 173 config DEBUG_DEVRES
 174         bool "Managed device resources verbose debug messages"
 175         depends on DEBUG_KERNEL
 176         help
 177           This option enables kernel parameter devres.log. If set to
 178           non-zero, devres debug messages are printed. Select this if
 179           you are having a problem with devres or want to debug
 180           resource management for a managed device. devres.log can be
 181           switched on and off from sysfs node.
 182
 183           If you are unsure about this, Say N here.
 184
 185 config SYS_HYPERVISOR
 186         bool
 187         default n
 188
 189 config GENERIC_CPU_DEVICES
 190         bool
 191         default n
 192
 193 config GENERIC_CPU_AUTOPROBE
 194         bool
 195
 196 config SOC_BUS
 197         bool
 198
 199 source "drivers/base/regmap/Kconfig"
 200
 201 config DMA_SHARED_BUFFER
 202         bool
 203         default n
 204         select ANON_INODES
 205         help
 206           This option enables the framework for buffer-sharing between
 207           multiple drivers. A buffer is associated with a file using driver
 208           APIs extension; the file's descriptor can then be passed on to other
 209           driver.
 210
 211 config DMA_CMA
 212         bool "DMA Contiguous Memory Allocator"
 213         depends on HAVE_DMA_CONTIGUOUS && CMA
 214         help
 215           This enables the Contiguous Memory Allocator which allows drivers
 216           to allocate big physically-contiguous blocks of memory for use with
 217           hardware components that do not support I/O map nor scatter-gather.
 218
 219           For more information see <include/linux/dma-contiguous.h>.
 220           If unsure, say "n".
 221
 222 if  DMA_CMA
 223 comment "Default contiguous memory area size:"
 224
 225 config CMA_SIZE_MBYTES
 226         int "Size in Mega Bytes"
 227         depends on !CMA_SIZE_SEL_PERCENTAGE
 228         default 16
 229         help
 230           Defines the size (in MiB) of the default memory area for Contiguous
 231           Memory Allocator.
 232
 233 config CMA_SIZE_PERCENTAGE
 234         int "Percentage of total memory"
 235         depends on !CMA_SIZE_SEL_MBYTES
 236         default 10
 237         help
 238           Defines the size of the default memory area for Contiguous Memory
 239           Allocator as a percentage of the total memory in the system.
 240
 241 choice
 242         prompt "Selected region size"
 243         default CMA_SIZE_SEL_MBYTES
 244
 245 config CMA_SIZE_SEL_MBYTES
 246         bool "Use mega bytes value only"
 247
 248 config CMA_SIZE_SEL_PERCENTAGE
 249         bool "Use percentage value only"
 250
 251 config CMA_SIZE_SEL_MIN
 252         bool "Use lower value (minimum)"
 253
 254 config CMA_SIZE_SEL_MAX
 255         bool "Use higher value (maximum)"
 256
 257 endchoice
 258
 259 config CMA_ALIGNMENT
 260         int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
 261         range 4 9
 262         default 8
 263         help
 264           DMA mapping framework by default aligns all buffers to the smallest
 265           PAGE_SIZE order which is greater than or equal to the requested buffer
 266           size. This works well for buffers up to a few hundreds kilobytes, but
 267           for larger buffers it just a memory waste. With this parameter you can
 268           specify the maximum PAGE_SIZE order for contiguous buffers. Larger
 269           buffers will be aligned only to this specified order. The order is
 270           expressed as a power of two multiplied by the PAGE_SIZE.
 271
 272           For example, if your system defaults to 4KiB pages, the order value
 273           of 8 means that the buffers will be aligned up to 1MiB only.
 274
 275           If unsure, leave the default value "8".
 276
 277 config CMA_AREAS
 278         int "Maximum count of the CMA device-private areas"
 279         default 7
 280         help
 281           CMA allows to create CMA areas for particular devices. This parameter
 282           sets the maximum number of such device private CMA areas in the
 283           system.
 284
 285           If unsure, leave the default value "7".
 286
 287 endif
 288
 289 endmenu