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 HAVE_CPU_AUTOPROBE
 191         def_bool ARCH_HAS_CPU_AUTOPROBE
 192
 193 config GENERIC_CPU_AUTOPROBE
 194         bool
 195         depends on !ARCH_HAS_CPU_AUTOPROBE
 196         select HAVE_CPU_AUTOPROBE
 197
 198 config SOC_BUS
 199         bool
 200
 201 source "drivers/base/regmap/Kconfig"
 202
 203 config DMA_SHARED_BUFFER
 204         bool
 205         default n
 206         select ANON_INODES
 207         help
 208           This option enables the framework for buffer-sharing between
 209           multiple drivers. A buffer is associated with a file using driver
 210           APIs extension; the file's descriptor can then be passed on to other
 211           driver.
 212
 213 config CMA
 214         bool "Contiguous Memory Allocator"
 215         depends on HAVE_DMA_CONTIGUOUS && HAVE_MEMBLOCK
 216         select MIGRATION
 217         select MEMORY_ISOLATION
 218         help
 219           This enables the Contiguous Memory Allocator which allows drivers
 220           to allocate big physically-contiguous blocks of memory for use with
 221           hardware components that do not support I/O map nor scatter-gather.
 222
 223           For more information see <include/linux/dma-contiguous.h>.
 224           If unsure, say "n".
 225
 226 if CMA
 227
 228 config CMA_DEBUG
 229         bool "CMA debug messages (DEVELOPMENT)"
 230         depends on DEBUG_KERNEL
 231         help
 232           Turns on debug messages in CMA.  This produces KERN_DEBUG
 233           messages for every CMA call as well as various messages while
 234           processing calls such as dma_alloc_from_contiguous().
 235           This option does not affect warning and error messages.
 236
 237 comment "Default contiguous memory area size:"
 238
 239 config CMA_SIZE_MBYTES
 240         int "Size in Mega Bytes"
 241         depends on !CMA_SIZE_SEL_PERCENTAGE
 242         default 16
 243         help
 244           Defines the size (in MiB) of the default memory area for Contiguous
 245           Memory Allocator.
 246
 247 config CMA_SIZE_PERCENTAGE
 248         int "Percentage of total memory"
 249         depends on !CMA_SIZE_SEL_MBYTES
 250         default 10
 251         help
 252           Defines the size of the default memory area for Contiguous Memory
 253           Allocator as a percentage of the total memory in the system.
 254
 255 choice
 256         prompt "Selected region size"
 257         default CMA_SIZE_SEL_MBYTES
 258
 259 config CMA_SIZE_SEL_MBYTES
 260         bool "Use mega bytes value only"
 261
 262 config CMA_SIZE_SEL_PERCENTAGE
 263         bool "Use percentage value only"
 264
 265 config CMA_SIZE_SEL_MIN
 266         bool "Use lower value (minimum)"
 267
 268 config CMA_SIZE_SEL_MAX
 269         bool "Use higher value (maximum)"
 270
 271 endchoice
 272
 273 config CMA_ALIGNMENT
 274         int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
 275         range 4 9
 276         default 8
 277         help
 278           DMA mapping framework by default aligns all buffers to the smallest
 279           PAGE_SIZE order which is greater than or equal to the requested buffer
 280           size. This works well for buffers up to a few hundreds kilobytes, but
 281           for larger buffers it just a memory waste. With this parameter you can
 282           specify the maximum PAGE_SIZE order for contiguous buffers. Larger
 283           buffers will be aligned only to this specified order. The order is
 284           expressed as a power of two multiplied by the PAGE_SIZE.
 285
 286           For example, if your system defaults to 4KiB pages, the order value
 287           of 8 means that the buffers will be aligned up to 1MiB only.
 288
 289           If unsure, leave the default value "8".
 290
 291 config CMA_AREAS
 292         int "Maximum count of the CMA device-private areas"
 293         default 7
 294         help
 295           CMA allows to create CMA areas for particular devices. This parameter
 296           sets the maximum number of such device private CMA areas in the
 297           system.
 298
 299           If unsure, leave the default value "7".
 300
 301 endif
 302
 303 endmenu