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