1 # SPDX-License-Identifier: GPL-2.0
3 # Character device configuration
6 menu "Character devices"
8 source "drivers/tty/Kconfig"
11 tristate "TTY driver to output user messages via printk"
12 depends on EXPERT && TTY
15 If you say Y here, the support for writing user messages (i.e.
16 console messages) via printk is available.
18 The feature is useful to inline user messages with kernel
20 In order to use this feature, you should output user messages
21 to /dev/ttyprintk or redirect console to this TTY.
25 config TTY_PRINTK_LEVEL
27 int "ttyprintk log level (1-7)"
31 Printk log level to use for ttyprintk messages.
34 tristate "Parallel printer support"
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>.
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.
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.
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>.
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.
60 bool "Support for console on line printer"
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.
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.
77 tristate "Support for user-space parallel port device drivers"
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
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.
89 To compile this driver as a module, choose M here: the
90 module will be called ppdev.
95 tristate "Virtio console"
100 Virtio console for use with hypervisors.
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.
112 tristate "IBM POWER Barrier Synchronization Register support"
113 depends on PPC_PSERIES
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
119 config POWERNV_OP_PANEL
120 tristate "IBM POWERNV Operator Panel Display support"
121 depends on PPC_POWERNV
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.
128 If you don't require access to the operator panel display from user
131 If unsure, say M here to build it as a module called powernv-op-panel.
133 source "drivers/char/ipmi/Kconfig"
136 tristate "NetWinder thermometer support"
137 depends on ARCH_NETWINDER
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.
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
148 tristate "NetWinder Button"
149 depends on ARCH_NETWINDER
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.
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
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.
165 To compile this driver as a module, choose M here: the
166 module will be called nwbutton.
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.
171 config NWBUTTON_REBOOT
172 bool "Reboot Using Button"
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>".
184 tristate "NetWinder flash support"
185 depends on ARCH_NETWINDER
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. :-)
193 To compile this driver as a module, choose M here: the
194 module will be called nwflash.
196 If you're not sure, say N.
198 source "drivers/char/hw_random/Kconfig"
201 tristate "Double Talk PC internal speech card support"
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'.
208 To compile this driver as a module, choose M here: the
209 module will be called dtlk.
212 tristate "Xilinx HWICAP Support"
213 depends on MICROBLAZE
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.
222 tristate "Siemens R3964 line discipline"
223 depends on TTY && BROKEN
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.
229 To compile this driver as a module, choose M here: the
230 module will be called n_r3964.
235 tristate "Applicom intelligent fieldbus card support"
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>.
244 To compile this driver as a module, choose M here: the
245 module will be called applicom.
250 tristate "Sony Vaio Programmable I/O Control Device support"
251 depends on X86_32 && PCI && INPUT
253 This driver enables access to the Sony Programmable I/O Control
254 Device which can be found in many (all ?) Sony Vaio laptops.
256 If you have one of those laptops, read
257 <file:Documentation/admin-guide/laptops/sonypi.rst>, and say Y or M here.
259 To compile this driver as a module, choose M here: the
260 module will be called sonypi.
263 tristate "TANBAC TB0219 GPIO support"
264 depends on TANBAC_TB022X
267 source "drivers/char/pcmcia/Kconfig"
270 tristate "ACP Modem (Mwave) support"
271 depends on X86 && TTY
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.
279 This version of the ACP Modem driver supports the IBM Thinkpad 600E,
280 600, and 770 that include on board ACP modem hardware.
282 The modem also supports the standard communications port interface
283 (ttySx) and is compatible with the Hayes AT Command Set.
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/>.
289 If you own one of the above IBM Thinkpads which has the Mwave chipset
292 To compile this driver as a module, choose M here: the
293 module will be called mwave.
296 tristate "NatSemi SCx200 GPIO Support"
300 Give userspace access to the GPIO pins on the National
301 Semiconductor SCx200 processors.
303 If compiled as a module, it will be called scx200_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
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
316 If compiled as a module, it will be called pc8736x_gpio.
319 tristate "NatSemi Base GPIO Support"
321 # selected by SCx200_GPIO and PC8736x_GPIO
322 # what about 2 selectors differing: m != y
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
329 bool "/dev/mem virtual device support"
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
335 When in doubt, say "Y".
338 bool "/dev/kmem virtual device support"
339 # On arm64, VMALLOC_START < PAGE_OFFSET, which confuses kmem read/write
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".
348 tristate "/dev/nvram support"
349 depends on X86 || HAVE_ARCH_NVRAM_OPS
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.
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.
364 This memory is conventionally called "NVRAM" on PowerPC machines,
365 "CMOS RAM" on PCs, "NVRAM" on Ataris and "PRAM" on Macintoshes.
367 To compile this driver as a module, choose M here: the
368 module will be called nvram.
371 tristate "RAW driver (/dev/raw/rawN)"
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.
378 Applications should preferably open the device (eg /dev/hda1)
379 with the O_DIRECT flag.
382 int "Maximum number of RAW devices to support (1-65536)"
383 depends on RAW_DRIVER
387 The maximum number of RAW devices that are supported.
388 Default is 256. Increase this number in case you need lots of
392 bool "/dev/port character device"
393 depends on ISA || PCI
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.
400 bool "HPET - High Precision Event Timer" if (X86 || IA64)
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.
409 bool "Allow mmap of HPET"
413 If you say Y here, user applications will be able to mmap
416 config HPET_MMAP_DEFAULT
417 bool "Enable HPET MMAP access by default"
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.
427 config HANGCHECK_TIMER
428 tristate "Hangcheck timer"
429 depends on X86 || IA64 || PPC64 || S390
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.
436 tristate "UV_MMTIMER Memory mapped RTC for SGI UV"
440 The uv_mmtimer device allows direct userspace access to the
443 source "drivers/char/tpm/Kconfig"
446 tristate "Telecom clock driver for ATCA SBC"
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.
458 source "drivers/s390/char/Kconfig"
460 source "drivers/char/xillybus/Kconfig"
463 tristate "SPARC Privileged ADI driver"
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.
476 config RANDOM_TRUST_CPU
477 bool "Trust the CPU manufacturer to initialize Linux's CRNG"
478 depends on ARCH_RANDOM
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".
491 config RANDOM_TRUST_BOOTLOADER
492 bool "Trust the bootloader to initialize Linux's CRNG"
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.