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 DEBUG_DRIVER
 149        bool "Driver Core verbose debug messages"
 150        depends on DEBUG_KERNEL
 151        help
 152          Say Y here if you want the Driver core to produce a bunch of
 153          debug messages to the system log. Select this if you are having a
 154          problem with the driver core and want to see more of what is
 155          going on.
 156
 157          If you are unsure about this, say N here.
 158
 159config DEBUG_DEVRES
 160        bool "Managed device resources verbose debug messages"
 161        depends on DEBUG_KERNEL
 162        help
 163          This option enables kernel parameter devres.log. If set to
 164          non-zero, devres debug messages are printed. Select this if
 165          you are having a problem with devres or want to debug
 166          resource management for a managed device. devres.log can be
 167          switched on and off from sysfs node.
 168
 169          If you are unsure about this, Say N here.
 170
 171config SYS_HYPERVISOR
 172        bool
 173        default n
 174
 175config GENERIC_CPU_DEVICES
 176        bool
 177        default n
 178
 179config SOC_BUS
 180        bool
 181
 182source "drivers/base/regmap/Kconfig"
 183
 184config DMA_SHARED_BUFFER
 185        bool
 186        default n
 187        select ANON_INODES
 188        help
 189          This option enables the framework for buffer-sharing between
 190          multiple drivers. A buffer is associated with a file using driver
 191          APIs extension; the file's descriptor can then be passed on to other
 192          driver.
 193
 194config CMA
 195        bool "Contiguous Memory Allocator"
 196        depends on HAVE_DMA_CONTIGUOUS && HAVE_MEMBLOCK
 197        select MIGRATION
 198        select MEMORY_ISOLATION
 199        help
 200          This enables the Contiguous Memory Allocator which allows drivers
 201          to allocate big physically-contiguous blocks of memory for use with
 202          hardware components that do not support I/O map nor scatter-gather.
 203
 204          For more information see <include/linux/dma-contiguous.h>.
 205          If unsure, say "n".
 206
 207if CMA
 208
 209config CMA_DEBUG
 210        bool "CMA debug messages (DEVELOPMENT)"
 211        depends on DEBUG_KERNEL
 212        help
 213          Turns on debug messages in CMA.  This produces KERN_DEBUG
 214          messages for every CMA call as well as various messages while
 215          processing calls such as dma_alloc_from_contiguous().
 216          This option does not affect warning and error messages.
 217
 218comment "Default contiguous memory area size:"
 219
 220config CMA_SIZE_MBYTES
 221        int "Size in Mega Bytes"
 222        depends on !CMA_SIZE_SEL_PERCENTAGE
 223        default 16
 224        help
 225          Defines the size (in MiB) of the default memory area for Contiguous
 226          Memory Allocator.
 227
 228config CMA_SIZE_PERCENTAGE
 229        int "Percentage of total memory"
 230        depends on !CMA_SIZE_SEL_MBYTES
 231        default 10
 232        help
 233          Defines the size of the default memory area for Contiguous Memory
 234          Allocator as a percentage of the total memory in the system.
 235
 236choice
 237        prompt "Selected region size"
 238        default CMA_SIZE_SEL_MBYTES
 239
 240config CMA_SIZE_SEL_MBYTES
 241        bool "Use mega bytes value only"
 242
 243config CMA_SIZE_SEL_PERCENTAGE
 244        bool "Use percentage value only"
 245
 246config CMA_SIZE_SEL_MIN
 247        bool "Use lower value (minimum)"
 248
 249config CMA_SIZE_SEL_MAX
 250        bool "Use higher value (maximum)"
 251
 252endchoice
 253
 254config CMA_ALIGNMENT
 255        int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
 256        range 4 9
 257        default 8
 258        help
 259          DMA mapping framework by default aligns all buffers to the smallest
 260          PAGE_SIZE order which is greater than or equal to the requested buffer
 261          size. This works well for buffers up to a few hundreds kilobytes, but
 262          for larger buffers it just a memory waste. With this parameter you can
 263          specify the maximum PAGE_SIZE order for contiguous buffers. Larger
 264          buffers will be aligned only to this specified order. The order is
 265          expressed as a power of two multiplied by the PAGE_SIZE.
 266
 267          For example, if your system defaults to 4KiB pages, the order value
 268          of 8 means that the buffers will be aligned up to 1MiB only.
 269
 270          If unsure, leave the default value "8".
 271
 272config CMA_AREAS
 273        int "Maximum count of the CMA device-private areas"
 274        default 7
 275        help
 276          CMA allows to create CMA areas for particular devices. This parameter
 277          sets the maximum number of such device private CMA areas in the
 278          system.
 279
 280          If unsure, leave the default value "7".
 281
 282endif
 283
 284endmenu
 285
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