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# SPDX-License-Identifier: GPL-2.0 # # Character device configuration # menu "Character devices" source "drivers/tty/Kconfig" config DEVMEM bool "/dev/mem virtual device support" default y help Say Y here if you want to support the /dev/mem device. The /dev/mem device is used to access areas of physical memory. When in doubt, say "Y". config DEVKMEM bool "/dev/kmem virtual device support" # On arm64, VMALLOC_START < PAGE_OFFSET, which confuses kmem read/write depends on !ARM64 help Say Y here if you want to support the /dev/kmem device. The /dev/kmem device is rarely used, but can be used for certain kind of kernel debugging operations. When in doubt, say "N". source "drivers/tty/serial/Kconfig" source "drivers/tty/serdev/Kconfig" config TTY_PRINTK tristate "TTY driver to output user messages via printk" depends on EXPERT && TTY default n ---help--- If you say Y here, the support for writing user messages (i.e. console messages) via printk is available. The feature is useful to inline user messages with kernel messages. In order to use this feature, you should output user messages to /dev/ttyprintk or redirect console to this TTY. If unsure, say N. config TTY_PRINTK_LEVEL depends on TTY_PRINTK int "ttyprintk log level (1-7)" range 1 7 default "6" help Printk log level to use for ttyprintk messages. config PRINTER tristate "Parallel printer support" depends on PARPORT ---help--- If you intend to attach a printer to the parallel port of your Linux box (as opposed to using a serial printer; if the connector at the printer has 9 or 25 holes ["female"], then it's serial), say Y. Also read the Printing-HOWTO, available from <http://www.tldp.org/docs.html#howto>. It is possible to share one parallel port among several devices (e.g. printer and ZIP drive) and it is safe to compile the corresponding drivers into the kernel. To compile this driver as a module, choose M here and read <file:Documentation/admin-guide/parport.rst>. The module will be called lp. If you have several parallel ports, you can specify which ports to use with the "lp" kernel command line option. (Try "man bootparam" or see the documentation of your boot loader (lilo or loadlin) about how to pass options to the kernel at boot time.) The syntax of the "lp" command line option can be found in <file:drivers/char/lp.c>. If you have more than 8 printers, you need to increase the LP_NO macro in lp.c and the PARPORT_MAX macro in parport.h. config LP_CONSOLE bool "Support for console on line printer" depends on PRINTER ---help--- If you want kernel messages to be printed out as they occur, you can have a console on the printer. This option adds support for doing that; to actually get it to happen you need to pass the option "console=lp0" to the kernel at boot time. If the printer is out of paper (or off, or unplugged, or too busy..) the kernel will stall until the printer is ready again. By defining CONSOLE_LP_STRICT to 0 (at your own risk) you can make the kernel continue when this happens, but it'll lose the kernel messages. If unsure, say N. config PPDEV tristate "Support for user-space parallel port device drivers" depends on PARPORT ---help--- Saying Y to this adds support for /dev/parport device nodes. This is needed for programs that want portable access to the parallel port, for instance deviceid (which displays Plug-and-Play device IDs). This is the parallel port equivalent of SCSI generic support (sg). It is safe to say N to this -- it is not needed for normal printing or parallel port CD-ROM/disk support. To compile this driver as a module, choose M here: the module will be called ppdev. If unsure, say N. source "drivers/tty/hvc/Kconfig" config VIRTIO_CONSOLE tristate "Virtio console" depends on VIRTIO && TTY select HVC_DRIVER help Virtio console for use with hypervisors. Also serves as a general-purpose serial device for data transfer between the guest and host. Character devices at /dev/vportNpn will be created when corresponding ports are found, where N is the device number and n is the port number within that device. If specified by the host, a sysfs attribute called 'name' will be populated with a name for the port which can be used by udev scripts to create a symlink to the device. config IBM_BSR tristate "IBM POWER Barrier Synchronization Register support" depends on PPC_PSERIES help This devices exposes a hardware mechanism for fast synchronization of threads across a large system which avoids bouncing a cacheline between several cores on a system config POWERNV_OP_PANEL tristate "IBM POWERNV Operator Panel Display support" depends on PPC_POWERNV default m help If you say Y here, a special character device node, /dev/op_panel, will be created which exposes the operator panel display on IBM Power Systems machines with FSPs. If you don't require access to the operator panel display from user space, say N. If unsure, say M here to build it as a module called powernv-op-panel. source "drivers/char/ipmi/Kconfig" config DS1620 tristate "NetWinder thermometer support" depends on ARCH_NETWINDER help Say Y here to include support for the thermal management hardware found in the NetWinder. This driver allows the user to control the temperature set points and to read the current temperature. It is also possible to say M here to build it as a module (ds1620) It is recommended to be used on a NetWinder, but it is not a necessity. config NWBUTTON tristate "NetWinder Button" depends on ARCH_NETWINDER ---help--- If you say Y here and create a character device node /dev/nwbutton with major and minor numbers 10 and 158 ("man mknod"), then every time the orange button is pressed a number of times, the number of times the button was pressed will be written to that device. This is most useful for applications, as yet unwritten, which perform actions based on how many times the button is pressed in a row. Do not hold the button down for too long, as the driver does not alter the behaviour of the hardware reset circuitry attached to the button; it will still execute a hard reset if the button is held down for longer than approximately five seconds. To compile this driver as a module, choose M here: the module will be called nwbutton. Most people will answer Y to this question and "Reboot Using Button" below to be able to initiate a system shutdown from the button. config NWBUTTON_REBOOT bool "Reboot Using Button" depends on NWBUTTON help If you say Y here, then you will be able to initiate a system shutdown and reboot by pressing the orange button a number of times. The number of presses to initiate the shutdown is two by default, but this can be altered by modifying the value of NUM_PRESSES_REBOOT in nwbutton.h and recompiling the driver or, if you compile the driver as a module, you can specify the number of presses at load time with "insmod button reboot_count=<something>". config NWFLASH tristate "NetWinder flash support" depends on ARCH_NETWINDER ---help--- If you say Y here and create a character device /dev/flash with major 10 and minor 160 you can manipulate the flash ROM containing the NetWinder firmware. Be careful as accidentally overwriting the flash contents can render your computer unbootable. On no account allow random users access to this device. :-) To compile this driver as a module, choose M here: the module will be called nwflash. If you're not sure, say N. source "drivers/char/hw_random/Kconfig" config NVRAM tristate "/dev/nvram support" depends on X86 || HAVE_ARCH_NVRAM_OPS default M68K || PPC ---help--- If you say Y here and create a character special file /dev/nvram with major number 10 and minor number 144 using mknod ("man mknod"), you get read and write access to the non-volatile memory. /dev/nvram may be used to view settings in NVRAM or to change them (with some utility). It could also be used to frequently save a few bits of very important data that may not be lost over power-off and for which writing to disk is too insecure. Note however that most NVRAM space in a PC belongs to the BIOS and you should NEVER idly tamper with it. See Ralf Brown's interrupt list for a guide to the use of CMOS bytes by your BIOS. This memory is conventionally called "NVRAM" on PowerPC machines, "CMOS RAM" on PCs, "NVRAM" on Ataris and "PRAM" on Macintoshes. To compile this driver as a module, choose M here: the module will be called nvram. # # These legacy RTC drivers just cause too many conflicts with the generic # RTC framework ... let's not even try to coexist any more. # if RTC_LIB=n config RTC tristate "Enhanced Real Time Clock Support (legacy PC RTC driver)" depends on ALPHA ---help--- If you say Y here and create a character special file /dev/rtc with major number 10 and minor number 135 using mknod ("man mknod"), you will get access to the real time clock (or hardware clock) built into your computer. Every PC has such a clock built in. It can be used to generate signals from as low as 1Hz up to 8192Hz, and can also be used as a 24 hour alarm. It reports status information via the file /proc/driver/rtc and its behaviour is set by various ioctls on /dev/rtc. If you run Linux on a multiprocessor machine and said Y to "Symmetric Multi Processing" above, you should say Y here to read and set the RTC in an SMP compatible fashion. If you think you have a use for such a device (such as periodic data sampling), then say Y here, and read <file:Documentation/admin-guide/rtc.rst> for details. To compile this driver as a module, choose M here: the module will be called rtc. config JS_RTC tristate "Enhanced Real Time Clock Support" depends on SPARC32 && PCI ---help--- If you say Y here and create a character special file /dev/rtc with major number 10 and minor number 135 using mknod ("man mknod"), you will get access to the real time clock (or hardware clock) built into your computer. Every PC has such a clock built in. It can be used to generate signals from as low as 1Hz up to 8192Hz, and can also be used as a 24 hour alarm. It reports status information via the file /proc/driver/rtc and its behaviour is set by various ioctls on /dev/rtc. If you think you have a use for such a device (such as periodic data sampling), then say Y here, and read <file:Documentation/admin-guide/rtc.rst> for details. To compile this driver as a module, choose M here: the module will be called js-rtc. config EFI_RTC bool "EFI Real Time Clock Services" depends on IA64 endif # RTC_LIB config DTLK tristate "Double Talk PC internal speech card support" depends on ISA help This driver is for the DoubleTalk PC, a speech synthesizer manufactured by RC Systems (<http://www.rcsys.com/>). It is also called the `internal DoubleTalk'. To compile this driver as a module, choose M here: the module will be called dtlk. config XILINX_HWICAP tristate "Xilinx HWICAP Support" depends on XILINX_VIRTEX || MICROBLAZE help This option enables support for Xilinx Internal Configuration Access Port (ICAP) driver. The ICAP is used on Xilinx Virtex FPGA platforms to partially reconfigure the FPGA at runtime. If unsure, say N. config R3964 tristate "Siemens R3964 line discipline" depends on TTY && BROKEN ---help--- This driver allows synchronous communication with devices using the Siemens R3964 packet protocol. Unless you are dealing with special hardware like PLCs, you are unlikely to need this. To compile this driver as a module, choose M here: the module will be called n_r3964. If unsure, say N. config APPLICOM tristate "Applicom intelligent fieldbus card support" depends on PCI ---help--- This driver provides the kernel-side support for the intelligent fieldbus cards made by Applicom International. More information about these cards can be found on the WWW at the address <http://www.applicom-int.com/>, or by email from David Woodhouse <dwmw2@infradead.org>. To compile this driver as a module, choose M here: the module will be called applicom. If unsure, say N. config SONYPI tristate "Sony Vaio Programmable I/O Control Device support" depends on X86_32 && PCI && INPUT ---help--- This driver enables access to the Sony Programmable I/O Control Device which can be found in many (all ?) Sony Vaio laptops. If you have one of those laptops, read <file:Documentation/admin-guide/laptops/sonypi.rst>, and say Y or M here. To compile this driver as a module, choose M here: the module will be called sonypi. config GPIO_TB0219 tristate "TANBAC TB0219 GPIO support" depends on TANBAC_TB022X select GPIO_VR41XX source "drivers/char/pcmcia/Kconfig" config MWAVE tristate "ACP Modem (Mwave) support" depends on X86 && TTY select SERIAL_8250 ---help--- The ACP modem (Mwave) for Linux is a WinModem. It is composed of a kernel driver and a user level application. Together these components support direct attachment to public switched telephone networks (PSTNs) and support selected world wide countries. This version of the ACP Modem driver supports the IBM Thinkpad 600E, 600, and 770 that include on board ACP modem hardware. The modem also supports the standard communications port interface (ttySx) and is compatible with the Hayes AT Command Set. The user level application needed to use this driver can be found at the IBM Linux Technology Center (LTC) web site: <http://www.ibm.com/linux/ltc/>. If you own one of the above IBM Thinkpads which has the Mwave chipset in it, say Y. To compile this driver as a module, choose M here: the module will be called mwave. config SCx200_GPIO tristate "NatSemi SCx200 GPIO Support" depends on SCx200 select NSC_GPIO help Give userspace access to the GPIO pins on the National Semiconductor SCx200 processors. If compiled as a module, it will be called scx200_gpio. config PC8736x_GPIO tristate "NatSemi PC8736x GPIO Support" depends on X86_32 && !UML default SCx200_GPIO # mostly N select NSC_GPIO # needed for support routines help Give userspace access to the GPIO pins on the National Semiconductor PC-8736x (x=[03456]) SuperIO chip. The chip has multiple functional units, inc several managed by hwmon/pc87360 driver. Tested with PC-87366 If compiled as a module, it will be called pc8736x_gpio. config NSC_GPIO tristate "NatSemi Base GPIO Support" depends on X86_32 # selected by SCx200_GPIO and PC8736x_GPIO # what about 2 selectors differing: m != y help Common support used (and needed) by scx200_gpio and pc8736x_gpio drivers. If those drivers are built as modules, this one will be too, named nsc_gpio config RAW_DRIVER tristate "RAW driver (/dev/raw/rawN)" depends on BLOCK help The raw driver permits block devices to be bound to /dev/raw/rawN. Once bound, I/O against /dev/raw/rawN uses efficient zero-copy I/O. See the raw(8) manpage for more details. Applications should preferably open the device (eg /dev/hda1) with the O_DIRECT flag. config MAX_RAW_DEVS int "Maximum number of RAW devices to support (1-65536)" depends on RAW_DRIVER range 1 65536 default "256" help The maximum number of RAW devices that are supported. Default is 256. Increase this number in case you need lots of raw devices. config HPET bool "HPET - High Precision Event Timer" if (X86 || IA64) default n depends on ACPI help If you say Y here, you will have a miscdevice named "/dev/hpet/". Each open selects one of the timers supported by the HPET. The timers are non-periodic and/or periodic. config HPET_MMAP bool "Allow mmap of HPET" default y depends on HPET help If you say Y here, user applications will be able to mmap the HPET registers. config HPET_MMAP_DEFAULT bool "Enable HPET MMAP access by default" default y depends on HPET_MMAP help In some hardware implementations, the page containing HPET registers may also contain other things that shouldn't be exposed to the user. This option selects the default (if kernel parameter hpet_mmap is not set) user access to the registers for applications that require it. config HANGCHECK_TIMER tristate "Hangcheck timer" depends on X86 || IA64 || PPC64 || S390 help The hangcheck-timer module detects when the system has gone out to lunch past a certain margin. It can reboot the system or merely print a warning. config UV_MMTIMER tristate "UV_MMTIMER Memory mapped RTC for SGI UV" depends on X86_UV default m help The uv_mmtimer device allows direct userspace access to the UV system timer. source "drivers/char/tpm/Kconfig" config TELCLOCK tristate "Telecom clock driver for ATCA SBC" depends on X86 default n help The telecom clock device is specific to the MPCBL0010 and MPCBL0050 ATCA computers and allows direct userspace access to the configuration of the telecom clock configuration settings. This device is used for hardware synchronization across the ATCA backplane fabric. Upon loading, the driver exports a sysfs directory, /sys/devices/platform/telco_clock, with a number of files for controlling the behavior of this hardware. config DEVPORT bool "/dev/port character device" depends on ISA || PCI default y help Say Y here if you want to support the /dev/port device. The /dev/port device is similar to /dev/mem, but for I/O ports. source "drivers/s390/char/Kconfig" source "drivers/char/xillybus/Kconfig" config ADI tristate "SPARC Privileged ADI driver" depends on SPARC64 default m help SPARC M7 and newer processors utilize ADI (Application Data Integrity) to version and protect memory. This driver provides read/write access to the ADI versions for privileged processes. This feature is also known as MCD (Memory Corruption Detection) and SSM (Silicon Secured Memory). Intended consumers of this driver include crash and makedumpfile. config RANDOM_TRUST_CPU bool "Initialize RNG using CPU RNG instructions" default y depends on ARCH_RANDOM help Initialize the RNG using random numbers supplied by the CPU's RNG instructions (e.g. RDRAND), if supported and available. These random numbers are never used directly, but are rather hashed into the main input pool, and this happens regardless of whether or not this option is enabled. Instead, this option controls whether the they are credited and hence can initialize the RNG. Additionally, other sources of randomness are always used, regardless of this setting. Enabling this implies trusting that the CPU can supply high quality and non-backdoored random numbers. Say Y here unless you have reason to mistrust your CPU or believe its RNG facilities may be faulty. This may also be configured at boot time with "random.trust_cpu=on/off". config RANDOM_TRUST_BOOTLOADER bool "Initialize RNG using bootloader-supplied seed" default y help Initialize the RNG using a seed supplied by the bootloader or boot environment (e.g. EFI or a bootloader-generated device tree). This seed is not used directly, but is rather hashed into the main input pool, and this happens regardless of whether or not this option is enabled. Instead, this option controls whether the seed is credited and hence can initialize the RNG. Additionally, other sources of randomness are always used, regardless of this setting. Enabling this implies trusting that the bootloader can supply high quality and non-backdoored seeds. Say Y here unless you have reason to mistrust your bootloader or believe its RNG facilities may be faulty. This may also be configured at boot time with "random.trust_bootloader=on/off". endmenu