1 # SPDX-License-Identifier: GPL-2.0
3 # Character device configuration
6 menu "Character devices"
8 source "drivers/tty/Kconfig"
11 bool "/dev/mem virtual device support"
14 Say Y here if you want to support the /dev/mem device.
15 The /dev/mem device is used to access areas of physical
17 When in doubt, say "Y".
20 bool "/dev/kmem virtual device support"
21 # On arm64, VMALLOC_START < PAGE_OFFSET, which confuses kmem read/write
24 Say Y here if you want to support the /dev/kmem device. The
25 /dev/kmem device is rarely used, but can be used for certain
26 kind of kernel debugging operations.
27 When in doubt, say "N".
30 bool "SGI Altix system controller communication support"
31 depends on (IA64_SGI_SN2 || IA64_GENERIC)
33 If you have an SGI Altix and you want to enable system
34 controller communication from user space (you want this!),
35 say Y. Otherwise, say N.
38 bool "SGI TIO CX driver support"
39 depends on (IA64_SGI_SN2 || IA64_GENERIC)
41 If you have an SGI Altix and you have fpga devices attached
42 to your TIO, say Y here, otherwise say N.
45 tristate "SGI FPGA Core Services driver support"
48 If you have an SGI Altix with an attached SABrick
49 say Y or M here, otherwise say N.
51 source "drivers/tty/serial/Kconfig"
52 source "drivers/tty/serdev/Kconfig"
55 tristate "TTY driver to output user messages via printk"
56 depends on EXPERT && TTY
59 If you say Y here, the support for writing user messages (i.e.
60 console messages) via printk is available.
62 The feature is useful to inline user messages with kernel
64 In order to use this feature, you should output user messages
65 to /dev/ttyprintk or redirect console to this TTY.
69 config TTY_PRINTK_LEVEL
71 int "ttyprintk log level (1-7)"
75 Printk log level to use for ttyprintk messages.
78 tristate "Parallel printer support"
81 If you intend to attach a printer to the parallel port of your Linux
82 box (as opposed to using a serial printer; if the connector at the
83 printer has 9 or 25 holes ["female"], then it's serial), say Y.
84 Also read the Printing-HOWTO, available from
85 <http://www.tldp.org/docs.html#howto>.
87 It is possible to share one parallel port among several devices
88 (e.g. printer and ZIP drive) and it is safe to compile the
89 corresponding drivers into the kernel.
91 To compile this driver as a module, choose M here and read
92 <file:Documentation/admin-guide/parport.rst>. The module will be called lp.
94 If you have several parallel ports, you can specify which ports to
95 use with the "lp" kernel command line option. (Try "man bootparam"
96 or see the documentation of your boot loader (lilo or loadlin) about
97 how to pass options to the kernel at boot time.) The syntax of the
98 "lp" command line option can be found in <file:drivers/char/lp.c>.
100 If you have more than 8 printers, you need to increase the LP_NO
101 macro in lp.c and the PARPORT_MAX macro in parport.h.
104 bool "Support for console on line printer"
107 If you want kernel messages to be printed out as they occur, you
108 can have a console on the printer. This option adds support for
109 doing that; to actually get it to happen you need to pass the
110 option "console=lp0" to the kernel at boot time.
112 If the printer is out of paper (or off, or unplugged, or too
113 busy..) the kernel will stall until the printer is ready again.
114 By defining CONSOLE_LP_STRICT to 0 (at your own risk) you
115 can make the kernel continue when this happens,
116 but it'll lose the kernel messages.
121 tristate "Support for user-space parallel port device drivers"
124 Saying Y to this adds support for /dev/parport device nodes. This
125 is needed for programs that want portable access to the parallel
126 port, for instance deviceid (which displays Plug-and-Play device
129 This is the parallel port equivalent of SCSI generic support (sg).
130 It is safe to say N to this -- it is not needed for normal printing
131 or parallel port CD-ROM/disk support.
133 To compile this driver as a module, choose M here: the
134 module will be called ppdev.
138 source "drivers/tty/hvc/Kconfig"
140 config VIRTIO_CONSOLE
141 tristate "Virtio console"
142 depends on VIRTIO && TTY
145 Virtio console for use with hypervisors.
147 Also serves as a general-purpose serial device for data
148 transfer between the guest and host. Character devices at
149 /dev/vportNpn will be created when corresponding ports are
150 found, where N is the device number and n is the port number
151 within that device. If specified by the host, a sysfs
152 attribute called 'name' will be populated with a name for
153 the port which can be used by udev scripts to create a
154 symlink to the device.
157 tristate "IBM POWER Barrier Synchronization Register support"
158 depends on PPC_PSERIES
160 This devices exposes a hardware mechanism for fast synchronization
161 of threads across a large system which avoids bouncing a cacheline
162 between several cores on a system
164 config POWERNV_OP_PANEL
165 tristate "IBM POWERNV Operator Panel Display support"
166 depends on PPC_POWERNV
169 If you say Y here, a special character device node, /dev/op_panel,
170 will be created which exposes the operator panel display on IBM
171 Power Systems machines with FSPs.
173 If you don't require access to the operator panel display from user
176 If unsure, say M here to build it as a module called powernv-op-panel.
178 source "drivers/char/ipmi/Kconfig"
181 tristate "NetWinder thermometer support"
182 depends on ARCH_NETWINDER
184 Say Y here to include support for the thermal management hardware
185 found in the NetWinder. This driver allows the user to control the
186 temperature set points and to read the current temperature.
188 It is also possible to say M here to build it as a module (ds1620)
189 It is recommended to be used on a NetWinder, but it is not a
193 tristate "NetWinder Button"
194 depends on ARCH_NETWINDER
196 If you say Y here and create a character device node /dev/nwbutton
197 with major and minor numbers 10 and 158 ("man mknod"), then every
198 time the orange button is pressed a number of times, the number of
199 times the button was pressed will be written to that device.
201 This is most useful for applications, as yet unwritten, which
202 perform actions based on how many times the button is pressed in a
205 Do not hold the button down for too long, as the driver does not
206 alter the behaviour of the hardware reset circuitry attached to the
207 button; it will still execute a hard reset if the button is held
208 down for longer than approximately five seconds.
210 To compile this driver as a module, choose M here: the
211 module will be called nwbutton.
213 Most people will answer Y to this question and "Reboot Using Button"
214 below to be able to initiate a system shutdown from the button.
216 config NWBUTTON_REBOOT
217 bool "Reboot Using Button"
220 If you say Y here, then you will be able to initiate a system
221 shutdown and reboot by pressing the orange button a number of times.
222 The number of presses to initiate the shutdown is two by default,
223 but this can be altered by modifying the value of NUM_PRESSES_REBOOT
224 in nwbutton.h and recompiling the driver or, if you compile the
225 driver as a module, you can specify the number of presses at load
226 time with "insmod button reboot_count=<something>".
229 tristate "NetWinder flash support"
230 depends on ARCH_NETWINDER
232 If you say Y here and create a character device /dev/flash with
233 major 10 and minor 160 you can manipulate the flash ROM containing
234 the NetWinder firmware. Be careful as accidentally overwriting the
235 flash contents can render your computer unbootable. On no account
236 allow random users access to this device. :-)
238 To compile this driver as a module, choose M here: the
239 module will be called nwflash.
241 If you're not sure, say N.
243 source "drivers/char/hw_random/Kconfig"
246 tristate "/dev/nvram support"
247 depends on ATARI || X86 || GENERIC_NVRAM
249 If you say Y here and create a character special file /dev/nvram
250 with major number 10 and minor number 144 using mknod ("man mknod"),
251 you get read and write access to the extra bytes of non-volatile
252 memory in the real time clock (RTC), which is contained in every PC
253 and most Ataris. The actual number of bytes varies, depending on the
254 nvram in the system, but is usually 114 (128-14 for the RTC).
256 This memory is conventionally called "CMOS RAM" on PCs and "NVRAM"
257 on Ataris. /dev/nvram may be used to view settings there, or to
258 change them (with some utility). It could also be used to frequently
259 save a few bits of very important data that may not be lost over
260 power-off and for which writing to disk is too insecure. Note
261 however that most NVRAM space in a PC belongs to the BIOS and you
262 should NEVER idly tamper with it. See Ralf Brown's interrupt list
263 for a guide to the use of CMOS bytes by your BIOS.
265 On Atari machines, /dev/nvram is always configured and does not need
268 To compile this driver as a module, choose M here: the
269 module will be called nvram.
272 # These legacy RTC drivers just cause too many conflicts with the generic
273 # RTC framework ... let's not even try to coexist any more.
278 tristate "Enhanced Real Time Clock Support (legacy PC RTC driver)"
281 If you say Y here and create a character special file /dev/rtc with
282 major number 10 and minor number 135 using mknod ("man mknod"), you
283 will get access to the real time clock (or hardware clock) built
286 Every PC has such a clock built in. It can be used to generate
287 signals from as low as 1Hz up to 8192Hz, and can also be used
288 as a 24 hour alarm. It reports status information via the file
289 /proc/driver/rtc and its behaviour is set by various ioctls on
292 If you run Linux on a multiprocessor machine and said Y to
293 "Symmetric Multi Processing" above, you should say Y here to read
294 and set the RTC in an SMP compatible fashion.
296 If you think you have a use for such a device (such as periodic data
297 sampling), then say Y here, and read <file:Documentation/rtc.txt>
300 To compile this driver as a module, choose M here: the
301 module will be called rtc.
304 tristate "Enhanced Real Time Clock Support"
305 depends on SPARC32 && PCI
307 If you say Y here and create a character special file /dev/rtc with
308 major number 10 and minor number 135 using mknod ("man mknod"), you
309 will get access to the real time clock (or hardware clock) built
312 Every PC has such a clock built in. It can be used to generate
313 signals from as low as 1Hz up to 8192Hz, and can also be used
314 as a 24 hour alarm. It reports status information via the file
315 /proc/driver/rtc and its behaviour is set by various ioctls on
318 If you think you have a use for such a device (such as periodic data
319 sampling), then say Y here, and read <file:Documentation/rtc.txt>
322 To compile this driver as a module, choose M here: the
323 module will be called js-rtc.
326 bool "EFI Real Time Clock Services"
332 tristate "Double Talk PC internal speech card support"
335 This driver is for the DoubleTalk PC, a speech synthesizer
336 manufactured by RC Systems (<http://www.rcsys.com/>). It is also
337 called the `internal DoubleTalk'.
339 To compile this driver as a module, choose M here: the
340 module will be called dtlk.
343 tristate "Xilinx HWICAP Support"
344 depends on XILINX_VIRTEX || MICROBLAZE
346 This option enables support for Xilinx Internal Configuration
347 Access Port (ICAP) driver. The ICAP is used on Xilinx Virtex
348 FPGA platforms to partially reconfigure the FPGA at runtime.
353 tristate "Siemens R3964 line discipline"
356 This driver allows synchronous communication with devices using the
357 Siemens R3964 packet protocol. Unless you are dealing with special
358 hardware like PLCs, you are unlikely to need this.
360 To compile this driver as a module, choose M here: the
361 module will be called n_r3964.
366 tristate "Applicom intelligent fieldbus card support"
369 This driver provides the kernel-side support for the intelligent
370 fieldbus cards made by Applicom International. More information
371 about these cards can be found on the WWW at the address
372 <http://www.applicom-int.com/>, or by email from David Woodhouse
373 <dwmw2@infradead.org>.
375 To compile this driver as a module, choose M here: the
376 module will be called applicom.
381 tristate "Sony Vaio Programmable I/O Control Device support"
382 depends on X86_32 && PCI && INPUT
384 This driver enables access to the Sony Programmable I/O Control
385 Device which can be found in many (all ?) Sony Vaio laptops.
387 If you have one of those laptops, read
388 <file:Documentation/laptops/sonypi.txt>, and say Y or M here.
390 To compile this driver as a module, choose M here: the
391 module will be called sonypi.
394 tristate "TANBAC TB0219 GPIO support"
395 depends on TANBAC_TB022X
398 source "drivers/char/pcmcia/Kconfig"
401 tristate "ACP Modem (Mwave) support"
402 depends on X86 && TTY
405 The ACP modem (Mwave) for Linux is a WinModem. It is composed of a
406 kernel driver and a user level application. Together these components
407 support direct attachment to public switched telephone networks (PSTNs)
408 and support selected world wide countries.
410 This version of the ACP Modem driver supports the IBM Thinkpad 600E,
411 600, and 770 that include on board ACP modem hardware.
413 The modem also supports the standard communications port interface
414 (ttySx) and is compatible with the Hayes AT Command Set.
416 The user level application needed to use this driver can be found at
417 the IBM Linux Technology Center (LTC) web site:
418 <http://www.ibm.com/linux/ltc/>.
420 If you own one of the above IBM Thinkpads which has the Mwave chipset
423 To compile this driver as a module, choose M here: the
424 module will be called mwave.
427 tristate "NatSemi SCx200 GPIO Support"
431 Give userspace access to the GPIO pins on the National
432 Semiconductor SCx200 processors.
434 If compiled as a module, it will be called scx200_gpio.
437 tristate "NatSemi PC8736x GPIO Support"
438 depends on X86_32 && !UML
439 default SCx200_GPIO # mostly N
440 select NSC_GPIO # needed for support routines
442 Give userspace access to the GPIO pins on the National
443 Semiconductor PC-8736x (x=[03456]) SuperIO chip. The chip
444 has multiple functional units, inc several managed by
445 hwmon/pc87360 driver. Tested with PC-87366
447 If compiled as a module, it will be called pc8736x_gpio.
450 tristate "NatSemi Base GPIO Support"
452 # selected by SCx200_GPIO and PC8736x_GPIO
453 # what about 2 selectors differing: m != y
455 Common support used (and needed) by scx200_gpio and
456 pc8736x_gpio drivers. If those drivers are built as
457 modules, this one will be too, named nsc_gpio
460 tristate "RAW driver (/dev/raw/rawN)"
463 The raw driver permits block devices to be bound to /dev/raw/rawN.
464 Once bound, I/O against /dev/raw/rawN uses efficient zero-copy I/O.
465 See the raw(8) manpage for more details.
467 Applications should preferably open the device (eg /dev/hda1)
468 with the O_DIRECT flag.
471 int "Maximum number of RAW devices to support (1-65536)"
472 depends on RAW_DRIVER
476 The maximum number of RAW devices that are supported.
477 Default is 256. Increase this number in case you need lots of
481 bool "HPET - High Precision Event Timer" if (X86 || IA64)
485 If you say Y here, you will have a miscdevice named "/dev/hpet/". Each
486 open selects one of the timers supported by the HPET. The timers are
487 non-periodic and/or periodic.
490 bool "Allow mmap of HPET"
494 If you say Y here, user applications will be able to mmap
497 config HPET_MMAP_DEFAULT
498 bool "Enable HPET MMAP access by default"
502 In some hardware implementations, the page containing HPET
503 registers may also contain other things that shouldn't be
504 exposed to the user. This option selects the default (if
505 kernel parameter hpet_mmap is not set) user access to the
506 registers for applications that require it.
508 config HANGCHECK_TIMER
509 tristate "Hangcheck timer"
510 depends on X86 || IA64 || PPC64 || S390
512 The hangcheck-timer module detects when the system has gone
513 out to lunch past a certain margin. It can reboot the system
514 or merely print a warning.
517 tristate "UV_MMTIMER Memory mapped RTC for SGI UV"
521 The uv_mmtimer device allows direct userspace access to the
524 source "drivers/char/tpm/Kconfig"
527 tristate "Telecom clock driver for ATCA SBC"
531 The telecom clock device is specific to the MPCBL0010 and MPCBL0050
532 ATCA computers and allows direct userspace access to the
533 configuration of the telecom clock configuration settings. This
534 device is used for hardware synchronization across the ATCA backplane
535 fabric. Upon loading, the driver exports a sysfs directory,
536 /sys/devices/platform/telco_clock, with a number of files for
537 controlling the behavior of this hardware.
540 bool "/dev/port character device"
541 depends on ISA || PCI
544 Say Y here if you want to support the /dev/port device. The /dev/port
545 device is similar to /dev/mem, but for I/O ports.
547 source "drivers/s390/char/Kconfig"
549 source "drivers/char/xillybus/Kconfig"
552 tristate "SPARC Privileged ADI driver"
556 SPARC M7 and newer processors utilize ADI (Application Data
557 Integrity) to version and protect memory. This driver provides
558 read/write access to the ADI versions for privileged processes.
559 This feature is also known as MCD (Memory Corruption Detection)
560 and SSM (Silicon Secured Memory). Intended consumers of this
561 driver include crash and makedumpfile.
565 config RANDOM_TRUST_CPU
566 bool "Trust the CPU manufacturer to initialize Linux's CRNG"
567 depends on X86 || S390 || PPC
570 Assume that CPU manufacturer (e.g., Intel or AMD for RDSEED or
571 RDRAND, IBM for the S390 and Power PC architectures) is trustworthy
572 for the purposes of initializing Linux's CRNG. Since this is not
573 something that can be independently audited, this amounts to trusting
574 that CPU manufacturer (perhaps with the insistence or mandate
575 of a Nation State's intelligence or law enforcement agencies)
576 has not installed a hidden back door to compromise the CPU's
577 random number generation facilities. This can also be configured
578 at boot with "random.trust_cpu=on/off".