linux/drivers/base/Kconfig
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   1menu "Generic Driver Options"
   2
   3config 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
  24config 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
  44config 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
  59config 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
  68config 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
  77config 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
  85config 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
 110config 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
 137config 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
 148config 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
 159config 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
 170config 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
 182config SYS_HYPERVISOR
 183        bool
 184        default n
 185
 186config GENERIC_CPU_DEVICES
 187        bool
 188        default n
 189
 190config SOC_BUS
 191        bool
 192
 193source "drivers/base/regmap/Kconfig"
 194
 195config 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
 205config 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
 218if CMA
 219
 220config 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
 229comment "Default contiguous memory area size:"
 230
 231config 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
 239config 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
 247choice
 248        prompt "Selected region size"
 249        default CMA_SIZE_SEL_MBYTES
 250
 251config CMA_SIZE_SEL_MBYTES
 252        bool "Use mega bytes value only"
 253
 254config CMA_SIZE_SEL_PERCENTAGE
 255        bool "Use percentage value only"
 256
 257config CMA_SIZE_SEL_MIN
 258        bool "Use lower value (minimum)"
 259
 260config CMA_SIZE_SEL_MAX
 261        bool "Use higher value (maximum)"
 262
 263endchoice
 264
 265config 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
 283config 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
 293endif
 294
 295endmenu
 296
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