1# SPDX-License-Identifier: GPL-2.0 2# 3# Character device configuration 4# 5 6menu "Character devices" 7 8source "drivers/tty/Kconfig" 9 10config 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 25config 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 33config 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 59config 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 76config 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 94config 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 111config 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 119config 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 133source "drivers/char/ipmi/Kconfig" 134 135config 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 147config 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 171config 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 183config 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 198source "drivers/char/hw_random/Kconfig" 199 200config 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 211config 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 221config 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 234config 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 249config 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 262config GPIO_TB0219 263 tristate "TANBAC TB0219 GPIO support" 264 depends on TANBAC_TB022X 265 select GPIO_VR41XX 266 267source "drivers/char/pcmcia/Kconfig" 268 269config 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 295config 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 305config 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 318config 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 328config 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 337config 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 347config 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 370config 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 381config 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 391config 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 399config 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 408config 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 416config 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 427config 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 435config 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 443source "drivers/char/tpm/Kconfig" 444 445config 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 458source "drivers/s390/char/Kconfig" 459 460source "drivers/char/xillybus/Kconfig" 461 462config 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 474endmenu 475 476config 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 491config 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. 499