drivers/char/Kconfig

   1 # SPDX-License-Identifier: GPL-2.0
   2 #
   3 # Character device configuration
   4 #
   5
   6 menu "Character devices"
   7
   8 source "drivers/tty/Kconfig"
   9
  10 config TTY_PRINTK
  11         tristate "TTY driver to output user messages via printk"
  12         depends on EXPERT && TTY
  13         default n
  14         help
  15           If you say Y here, the support for writing user messages (i.e.
  16           console messages) via printk is available.
  17
  18           The feature is useful to inline user messages with kernel
  19           messages.
  20           In order to use this feature, you should output user messages
  21           to /dev/ttyprintk or redirect console to this TTY.
  22
  23           If unsure, say N.
  24
  25 config TTY_PRINTK_LEVEL
  26         depends on TTY_PRINTK
  27         int "ttyprintk log level (1-7)"
  28         range 1 7
  29         default "6"
  30         help
  31           Printk log level to use for ttyprintk messages.
  32
  33 config PRINTER
  34         tristate "Parallel printer support"
  35         depends on PARPORT
  36         help
  37           If you intend to attach a printer to the parallel port of your Linux
  38           box (as opposed to using a serial printer; if the connector at the
  39           printer has 9 or 25 holes ["female"], then it's serial), say Y.
  40           Also read the Printing-HOWTO, available from
  41           <https://www.tldp.org/docs.html#howto>.
  42
  43           It is possible to share one parallel port among several devices
  44           (e.g. printer and ZIP drive) and it is safe to compile the
  45           corresponding drivers into the kernel.
  46
  47           To compile this driver as a module, choose M here and read
  48           <file:Documentation/admin-guide/parport.rst>.  The module will be called lp.
  49
  50           If you have several parallel ports, you can specify which ports to
  51           use with the "lp" kernel command line option.  (Try "man bootparam"
  52           or see the documentation of your boot loader (lilo or loadlin) about
  53           how to pass options to the kernel at boot time.)  The syntax of the
  54           "lp" command line option can be found in <file:drivers/char/lp.c>.
  55
  56           If you have more than 8 printers, you need to increase the LP_NO
  57           macro in lp.c and the PARPORT_MAX macro in parport.h.
  58
  59 config LP_CONSOLE
  60         bool "Support for console on line printer"
  61         depends on PRINTER
  62         help
  63           If you want kernel messages to be printed out as they occur, you
  64           can have a console on the printer. This option adds support for
  65           doing that; to actually get it to happen you need to pass the
  66           option "console=lp0" to the kernel at boot time.
  67
  68           If the printer is out of paper (or off, or unplugged, or too
  69           busy..) the kernel will stall until the printer is ready again.
  70           By defining CONSOLE_LP_STRICT to 0 (at your own risk) you
  71           can make the kernel continue when this happens,
  72           but it'll lose the kernel messages.
  73
  74           If unsure, say N.
  75
  76 config PPDEV
  77         tristate "Support for user-space parallel port device drivers"
  78         depends on PARPORT
  79         help
  80           Saying Y to this adds support for /dev/parport device nodes.  This
  81           is needed for programs that want portable access to the parallel
  82           port, for instance deviceid (which displays Plug-and-Play device
  83           IDs).
  84
  85           This is the parallel port equivalent of SCSI generic support (sg).
  86           It is safe to say N to this -- it is not needed for normal printing
  87           or parallel port CD-ROM/disk support.
  88
  89           To compile this driver as a module, choose M here: the
  90           module will be called ppdev.
  91
  92           If unsure, say N.
  93
  94 config VIRTIO_CONSOLE
  95         tristate "Virtio console"
  96         depends on VIRTIO && TTY
  97         select HVC_DRIVER
  98         help
  99           Virtio console for use with hypervisors.
 100
 101           Also serves as a general-purpose serial device for data
 102           transfer between the guest and host.  Character devices at
 103           /dev/vportNpn will be created when corresponding ports are
 104           found, where N is the device number and n is the port number
 105           within that device.  If specified by the host, a sysfs
 106           attribute called 'name' will be populated with a name for
 107           the port which can be used by udev scripts to create a
 108           symlink to the device.
 109
 110 config IBM_BSR
 111         tristate "IBM POWER Barrier Synchronization Register support"
 112         depends on PPC_PSERIES
 113         help
 114           This devices exposes a hardware mechanism for fast synchronization
 115           of threads across a large system which avoids bouncing a cacheline
 116           between several cores on a system
 117
 118 config POWERNV_OP_PANEL
 119         tristate "IBM POWERNV Operator Panel Display support"
 120         depends on PPC_POWERNV
 121         default m
 122         help
 123           If you say Y here, a special character device node, /dev/op_panel,
 124           will be created which exposes the operator panel display on IBM
 125           Power Systems machines with FSPs.
 126
 127           If you don't require access to the operator panel display from user
 128           space, say N.
 129
 130           If unsure, say M here to build it as a module called powernv-op-panel.
 131
 132 source "drivers/char/ipmi/Kconfig"
 133
 134 config DS1620
 135         tristate "NetWinder thermometer support"
 136         depends on ARCH_NETWINDER
 137         help
 138           Say Y here to include support for the thermal management hardware
 139           found in the NetWinder. This driver allows the user to control the
 140           temperature set points and to read the current temperature.
 141
 142           It is also possible to say M here to build it as a module (ds1620)
 143           It is recommended to be used on a NetWinder, but it is not a
 144           necessity.
 145
 146 config NWBUTTON
 147         tristate "NetWinder Button"
 148         depends on ARCH_NETWINDER
 149         help
 150           If you say Y here and create a character device node /dev/nwbutton
 151           with major and minor numbers 10 and 158 ("man mknod"), then every
 152           time the orange button is pressed a number of times, the number of
 153           times the button was pressed will be written to that device.
 154
 155           This is most useful for applications, as yet unwritten, which
 156           perform actions based on how many times the button is pressed in a
 157           row.
 158
 159           Do not hold the button down for too long, as the driver does not
 160           alter the behaviour of the hardware reset circuitry attached to the
 161           button; it will still execute a hard reset if the button is held
 162           down for longer than approximately five seconds.
 163
 164           To compile this driver as a module, choose M here: the
 165           module will be called nwbutton.
 166
 167           Most people will answer Y to this question and "Reboot Using Button"
 168           below to be able to initiate a system shutdown from the button.
 169
 170 config NWBUTTON_REBOOT
 171         bool "Reboot Using Button"
 172         depends on NWBUTTON
 173         help
 174           If you say Y here, then you will be able to initiate a system
 175           shutdown and reboot by pressing the orange button a number of times.
 176           The number of presses to initiate the shutdown is two by default,
 177           but this can be altered by modifying the value of NUM_PRESSES_REBOOT
 178           in nwbutton.h and recompiling the driver or, if you compile the
 179           driver as a module, you can specify the number of presses at load
 180           time with "insmod button reboot_count=<something>".
 181
 182 config NWFLASH
 183         tristate "NetWinder flash support"
 184         depends on ARCH_NETWINDER
 185         help
 186           If you say Y here and create a character device /dev/flash with
 187           major 10 and minor 160 you can manipulate the flash ROM containing
 188           the NetWinder firmware. Be careful as accidentally overwriting the
 189           flash contents can render your computer unbootable. On no account
 190           allow random users access to this device. :-)
 191
 192           To compile this driver as a module, choose M here: the
 193           module will be called nwflash.
 194
 195           If you're not sure, say N.
 196
 197 source "drivers/char/hw_random/Kconfig"
 198
 199 config DTLK
 200         tristate "Double Talk PC internal speech card support"
 201         depends on ISA
 202         help
 203           This driver is for the DoubleTalk PC, a speech synthesizer
 204           manufactured by RC Systems (<https://www.rcsys.com/>).  It is also
 205           called the `internal DoubleTalk'.
 206
 207           To compile this driver as a module, choose M here: the
 208           module will be called dtlk.
 209
 210 config XILINX_HWICAP
 211         tristate "Xilinx HWICAP Support"
 212         depends on MICROBLAZE
 213         help
 214           This option enables support for Xilinx Internal Configuration
 215           Access Port (ICAP) driver.  The ICAP is used on Xilinx Virtex
 216           FPGA platforms to partially reconfigure the FPGA at runtime.
 217
 218           If unsure, say N.
 219
 220 config R3964
 221         tristate "Siemens R3964 line discipline"
 222         depends on TTY && BROKEN
 223         help
 224           This driver allows synchronous communication with devices using the
 225           Siemens R3964 packet protocol. Unless you are dealing with special
 226           hardware like PLCs, you are unlikely to need this.
 227
 228           To compile this driver as a module, choose M here: the
 229           module will be called n_r3964.
 230
 231           If unsure, say N.
 232
 233 config APPLICOM
 234         tristate "Applicom intelligent fieldbus card support"
 235         depends on PCI
 236         help
 237           This driver provides the kernel-side support for the intelligent
 238           fieldbus cards made by Applicom International. More information
 239           about these cards can be found on the WWW at the address
 240           <https://www.applicom-int.com/>, or by email from David Woodhouse
 241           <dwmw2@infradead.org>.
 242
 243           To compile this driver as a module, choose M here: the
 244           module will be called applicom.
 245
 246           If unsure, say N.
 247
 248 config SONYPI
 249         tristate "Sony Vaio Programmable I/O Control Device support"
 250         depends on X86_32 && PCI && INPUT
 251         help
 252           This driver enables access to the Sony Programmable I/O Control
 253           Device which can be found in many (all ?) Sony Vaio laptops.
 254
 255           If you have one of those laptops, read
 256           <file:Documentation/admin-guide/laptops/sonypi.rst>, and say Y or M here.
 257
 258           To compile this driver as a module, choose M here: the
 259           module will be called sonypi.
 260
 261 config GPIO_TB0219
 262         tristate "TANBAC TB0219 GPIO support"
 263         depends on TANBAC_TB022X
 264         select GPIO_VR41XX
 265
 266 source "drivers/char/pcmcia/Kconfig"
 267
 268 config MWAVE
 269         tristate "ACP Modem (Mwave) support"
 270         depends on X86 && TTY
 271         select SERIAL_8250
 272         help
 273           The ACP modem (Mwave) for Linux is a WinModem. It is composed of a
 274           kernel driver and a user level application. Together these components
 275           support direct attachment to public switched telephone networks (PSTNs)
 276           and support selected world wide countries.
 277
 278           This version of the ACP Modem driver supports the IBM Thinkpad 600E,
 279           600, and 770 that include on board ACP modem hardware.
 280
 281           The modem also supports the standard communications port interface
 282           (ttySx) and is compatible with the Hayes AT Command Set.
 283
 284           The user level application needed to use this driver can be found at
 285           the IBM Linux Technology Center (LTC) web site:
 286           <http://www.ibm.com/linux/ltc/>.
 287
 288           If you own one of the above IBM Thinkpads which has the Mwave chipset
 289           in it, say Y.
 290
 291           To compile this driver as a module, choose M here: the
 292           module will be called mwave.
 293
 294 config SCx200_GPIO
 295         tristate "NatSemi SCx200 GPIO Support"
 296         depends on SCx200
 297         select NSC_GPIO
 298         help
 299           Give userspace access to the GPIO pins on the National
 300           Semiconductor SCx200 processors.
 301
 302           If compiled as a module, it will be called scx200_gpio.
 303
 304 config PC8736x_GPIO
 305         tristate "NatSemi PC8736x GPIO Support"
 306         depends on X86_32 && !UML
 307         default SCx200_GPIO     # mostly N
 308         select NSC_GPIO         # needed for support routines
 309         help
 310           Give userspace access to the GPIO pins on the National
 311           Semiconductor PC-8736x (x=[03456]) SuperIO chip.  The chip
 312           has multiple functional units, inc several managed by
 313           hwmon/pc87360 driver.  Tested with PC-87366
 314
 315           If compiled as a module, it will be called pc8736x_gpio.
 316
 317 config NSC_GPIO
 318         tristate "NatSemi Base GPIO Support"
 319         depends on X86_32
 320         # selected by SCx200_GPIO and PC8736x_GPIO
 321         # what about 2 selectors differing: m != y
 322         help
 323           Common support used (and needed) by scx200_gpio and
 324           pc8736x_gpio drivers.  If those drivers are built as
 325           modules, this one will be too, named nsc_gpio
 326
 327 config DEVMEM
 328         bool "/dev/mem virtual device support"
 329         default y
 330         help
 331           Say Y here if you want to support the /dev/mem device.
 332           The /dev/mem device is used to access areas of physical
 333           memory.
 334           When in doubt, say "Y".
 335
 336 config DEVKMEM
 337         bool "/dev/kmem virtual device support"
 338         # On arm64, VMALLOC_START < PAGE_OFFSET, which confuses kmem read/write
 339         depends on !ARM64
 340         help
 341           Say Y here if you want to support the /dev/kmem device. The
 342           /dev/kmem device is rarely used, but can be used for certain
 343           kind of kernel debugging operations.
 344           When in doubt, say "N".
 345
 346 config NVRAM
 347         tristate "/dev/nvram support"
 348         depends on X86 || HAVE_ARCH_NVRAM_OPS
 349         default M68K || PPC
 350         help
 351           If you say Y here and create a character special file /dev/nvram
 352           with major number 10 and minor number 144 using mknod ("man mknod"),
 353           you get read and write access to the non-volatile memory.
 354
 355           /dev/nvram may be used to view settings in NVRAM or to change them
 356           (with some utility). It could also be used to frequently
 357           save a few bits of very important data that may not be lost over
 358           power-off and for which writing to disk is too insecure. Note
 359           however that most NVRAM space in a PC belongs to the BIOS and you
 360           should NEVER idly tamper with it. See Ralf Brown's interrupt list
 361           for a guide to the use of CMOS bytes by your BIOS.
 362
 363           This memory is conventionally called "NVRAM" on PowerPC machines,
 364           "CMOS RAM" on PCs, "NVRAM" on Ataris and "PRAM" on Macintoshes.
 365
 366           To compile this driver as a module, choose M here: the
 367           module will be called nvram.
 368
 369 config RAW_DRIVER
 370         tristate "RAW driver (/dev/raw/rawN)"
 371         depends on BLOCK
 372         help
 373           The raw driver permits block devices to be bound to /dev/raw/rawN.
 374           Once bound, I/O against /dev/raw/rawN uses efficient zero-copy I/O.
 375           See the raw(8) manpage for more details.
 376
 377           Applications should preferably open the device (eg /dev/hda1)
 378           with the O_DIRECT flag.
 379
 380 config MAX_RAW_DEVS
 381         int "Maximum number of RAW devices to support (1-65536)"
 382         depends on RAW_DRIVER
 383         range 1 65536
 384         default "256"
 385         help
 386           The maximum number of RAW devices that are supported.
 387           Default is 256. Increase this number in case you need lots of
 388           raw devices.
 389
 390 config DEVPORT
 391         bool "/dev/port character device"
 392         depends on ISA || PCI
 393         default y
 394         help
 395           Say Y here if you want to support the /dev/port device. The /dev/port
 396           device is similar to /dev/mem, but for I/O ports.
 397
 398 config HPET
 399         bool "HPET - High Precision Event Timer" if (X86 || IA64)
 400         default n
 401         depends on ACPI
 402         help
 403           If you say Y here, you will have a miscdevice named "/dev/hpet/".  Each
 404           open selects one of the timers supported by the HPET.  The timers are
 405           non-periodic and/or periodic.
 406
 407 config HPET_MMAP
 408         bool "Allow mmap of HPET"
 409         default y
 410         depends on HPET
 411         help
 412           If you say Y here, user applications will be able to mmap
 413           the HPET registers.
 414
 415 config HPET_MMAP_DEFAULT
 416         bool "Enable HPET MMAP access by default"
 417         default y
 418         depends on HPET_MMAP
 419         help
 420           In some hardware implementations, the page containing HPET
 421           registers may also contain other things that shouldn't be
 422           exposed to the user.  This option selects the default (if
 423           kernel parameter hpet_mmap is not set) user access to the
 424           registers for applications that require it.
 425
 426 config HANGCHECK_TIMER
 427         tristate "Hangcheck timer"
 428         depends on X86 || IA64 || PPC64 || S390
 429         help
 430           The hangcheck-timer module detects when the system has gone
 431           out to lunch past a certain margin.  It can reboot the system
 432           or merely print a warning.
 433
 434 config UV_MMTIMER
 435         tristate "UV_MMTIMER Memory mapped RTC for SGI UV"
 436         depends on X86_UV
 437         default m
 438         help
 439           The uv_mmtimer device allows direct userspace access to the
 440           UV system timer.
 441
 442 source "drivers/char/tpm/Kconfig"
 443
 444 config TELCLOCK
 445         tristate "Telecom clock driver for ATCA SBC"
 446         depends on X86
 447         default n
 448         help
 449           The telecom clock device is specific to the MPCBL0010 and MPCBL0050
 450           ATCA computers and allows direct userspace access to the
 451           configuration of the telecom clock configuration settings.  This
 452           device is used for hardware synchronization across the ATCA backplane
 453           fabric.  Upon loading, the driver exports a sysfs directory,
 454           /sys/devices/platform/telco_clock, with a number of files for
 455           controlling the behavior of this hardware.
 456
 457 source "drivers/s390/char/Kconfig"
 458
 459 source "drivers/char/xillybus/Kconfig"
 460
 461 config ADI
 462         tristate "SPARC Privileged ADI driver"
 463         depends on SPARC64
 464         default m
 465         help
 466           SPARC M7 and newer processors utilize ADI (Application Data
 467           Integrity) to version and protect memory.  This driver provides
 468           read/write access to the ADI versions for privileged processes.
 469           This feature is also known as MCD (Memory Corruption Detection)
 470           and SSM (Silicon Secured Memory).  Intended consumers of this
 471           driver include crash and makedumpfile.
 472
 473 endmenu
 474
 475 config RANDOM_TRUST_CPU
 476         bool "Trust the CPU manufacturer to initialize Linux's CRNG"
 477         depends on ARCH_RANDOM
 478         default n
 479         help
 480         Assume that CPU manufacturer (e.g., Intel or AMD for RDSEED or
 481         RDRAND, IBM for the S390 and Power PC architectures) is trustworthy
 482         for the purposes of initializing Linux's CRNG.  Since this is not
 483         something that can be independently audited, this amounts to trusting
 484         that CPU manufacturer (perhaps with the insistence or mandate
 485         of a Nation State's intelligence or law enforcement agencies)
 486         has not installed a hidden back door to compromise the CPU's
 487         random number generation facilities. This can also be configured
 488         at boot with "random.trust_cpu=on/off".
 489
 490 config RANDOM_TRUST_BOOTLOADER
 491         bool "Trust the bootloader to initialize Linux's CRNG"
 492         help
 493         Some bootloaders can provide entropy to increase the kernel's initial
 494         device randomness. Say Y here to assume the entropy provided by the
 495         booloader is trustworthy so it will be added to the kernel's entropy
 496         pool. Otherwise, say N here so it will be regarded as device input that
 497         only mixes the entropy pool.