drivers/base/Kconfig

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