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