drivers/base/Kconfig

   1 menu "Generic Driver Options"
   2
   3 config 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
  23 config 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
  42 config 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 rootfs 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
  57 config 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
  66 config 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
  75 config 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
  83 config 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
 108 config 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
 135 config 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
 146 config 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
 157 config 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
 168 config 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
 180 config SYS_HYPERVISOR
 181         bool
 182         default n
 183
 184 config GENERIC_CPU_DEVICES
 185         bool
 186         default n
 187
 188 config SOC_BUS
 189         bool
 190
 191 source "drivers/base/regmap/Kconfig"
 192
 193 config 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
 203 config DMA_CMA
 204         bool "DMA Contiguous Memory Allocator"
 205         depends on HAVE_DMA_CONTIGUOUS && CMA
 206         help
 207           This enables the Contiguous Memory Allocator which allows drivers
 208           to allocate big physically-contiguous blocks of memory for use with
 209           hardware components that do not support I/O map nor scatter-gather.
 210
 211           For more information see <include/linux/dma-contiguous.h>.
 212           If unsure, say "n".
 213
 214 if  DMA_CMA
 215 comment "Default contiguous memory area size:"
 216
 217 config CMA_SIZE_MBYTES
 218         int "Size in Mega Bytes"
 219         depends on !CMA_SIZE_SEL_PERCENTAGE
 220         default 16
 221         help
 222           Defines the size (in MiB) of the default memory area for Contiguous
 223           Memory Allocator.
 224
 225 config CMA_SIZE_PERCENTAGE
 226         int "Percentage of total memory"
 227         depends on !CMA_SIZE_SEL_MBYTES
 228         default 10
 229         help
 230           Defines the size of the default memory area for Contiguous Memory
 231           Allocator as a percentage of the total memory in the system.
 232
 233 choice
 234         prompt "Selected region size"
 235         default CMA_SIZE_SEL_MBYTES
 236
 237 config CMA_SIZE_SEL_MBYTES
 238         bool "Use mega bytes value only"
 239
 240 config CMA_SIZE_SEL_PERCENTAGE
 241         bool "Use percentage value only"
 242
 243 config CMA_SIZE_SEL_MIN
 244         bool "Use lower value (minimum)"
 245
 246 config CMA_SIZE_SEL_MAX
 247         bool "Use higher value (maximum)"
 248
 249 endchoice
 250
 251 config CMA_ALIGNMENT
 252         int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
 253         range 4 9
 254         default 8
 255         help
 256           DMA mapping framework by default aligns all buffers to the smallest
 257           PAGE_SIZE order which is greater than or equal to the requested buffer
 258           size. This works well for buffers up to a few hundreds kilobytes, but
 259           for larger buffers it just a memory waste. With this parameter you can
 260           specify the maximum PAGE_SIZE order for contiguous buffers. Larger
 261           buffers will be aligned only to this specified order. The order is
 262           expressed as a power of two multiplied by the PAGE_SIZE.
 263
 264           For example, if your system defaults to 4KiB pages, the order value
 265           of 8 means that the buffers will be aligned up to 1MiB only.
 266
 267           If unsure, leave the default value "8".
 268
 269 config CMA_AREAS
 270         int "Maximum count of the CMA device-private areas"
 271         default 7
 272         help
 273           CMA allows to create CMA areas for particular devices. This parameter
 274           sets the maximum number of such device private CMA areas in the
 275           system.
 276
 277           If unsure, leave the default value "7".
 278
 279 endif
 280
 281 endmenu