# SPDX-License-Identifier: GPL-2.0
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#
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# Character device configuration
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#
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menu "Character devices"
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source "drivers/tty/Kconfig"
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config DEVMEM
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bool "/dev/mem virtual device support"
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default y
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help
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Say Y here if you want to support the /dev/mem device.
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The /dev/mem device is used to access areas of physical
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memory.
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When in doubt, say "Y".
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config DEVKMEM
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bool "/dev/kmem virtual device support"
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# On arm64, VMALLOC_START < PAGE_OFFSET, which confuses kmem read/write
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depends on !ARM64
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help
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Say Y here if you want to support the /dev/kmem device. The
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/dev/kmem device is rarely used, but can be used for certain
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kind of kernel debugging operations.
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When in doubt, say "N".
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config SGI_SNSC
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bool "SGI Altix system controller communication support"
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depends on (IA64_SGI_SN2 || IA64_GENERIC)
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help
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If you have an SGI Altix and you want to enable system
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controller communication from user space (you want this!),
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say Y. Otherwise, say N.
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config SGI_TIOCX
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bool "SGI TIO CX driver support"
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depends on (IA64_SGI_SN2 || IA64_GENERIC)
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help
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If you have an SGI Altix and you have fpga devices attached
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to your TIO, say Y here, otherwise say N.
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config SGI_MBCS
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tristate "SGI FPGA Core Services driver support"
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depends on SGI_TIOCX
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help
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If you have an SGI Altix with an attached SABrick
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say Y or M here, otherwise say N.
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source "drivers/tty/serial/Kconfig"
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source "drivers/tty/serdev/Kconfig"
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config TTY_PRINTK
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tristate "TTY driver to output user messages via printk"
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depends on EXPERT && TTY
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default n
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---help---
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If you say Y here, the support for writing user messages (i.e.
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console messages) via printk is available.
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The feature is useful to inline user messages with kernel
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messages.
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In order to use this feature, you should output user messages
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to /dev/ttyprintk or redirect console to this TTY.
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If unsure, say N.
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config PRINTER
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tristate "Parallel printer support"
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depends on PARPORT
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---help---
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If you intend to attach a printer to the parallel port of your Linux
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box (as opposed to using a serial printer; if the connector at the
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printer has 9 or 25 holes ["female"], then it's serial), say Y.
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Also read the Printing-HOWTO, available from
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<http://www.tldp.org/docs.html#howto>.
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It is possible to share one parallel port among several devices
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(e.g. printer and ZIP drive) and it is safe to compile the
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corresponding drivers into the kernel.
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To compile this driver as a module, choose M here and read
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<file:Documentation/admin-guide/parport.rst>. The module will be called lp.
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If you have several parallel ports, you can specify which ports to
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use with the "lp" kernel command line option. (Try "man bootparam"
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or see the documentation of your boot loader (lilo or loadlin) about
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how to pass options to the kernel at boot time.) The syntax of the
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"lp" command line option can be found in <file:drivers/char/lp.c>.
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If you have more than 8 printers, you need to increase the LP_NO
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macro in lp.c and the PARPORT_MAX macro in parport.h.
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config LP_CONSOLE
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bool "Support for console on line printer"
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depends on PRINTER
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---help---
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If you want kernel messages to be printed out as they occur, you
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can have a console on the printer. This option adds support for
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doing that; to actually get it to happen you need to pass the
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option "console=lp0" to the kernel at boot time.
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If the printer is out of paper (or off, or unplugged, or too
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busy..) the kernel will stall until the printer is ready again.
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By defining CONSOLE_LP_STRICT to 0 (at your own risk) you
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can make the kernel continue when this happens,
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but it'll lose the kernel messages.
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If unsure, say N.
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config PPDEV
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tristate "Support for user-space parallel port device drivers"
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depends on PARPORT
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---help---
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Saying Y to this adds support for /dev/parport device nodes. This
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is needed for programs that want portable access to the parallel
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port, for instance deviceid (which displays Plug-and-Play device
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IDs).
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This is the parallel port equivalent of SCSI generic support (sg).
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It is safe to say N to this -- it is not needed for normal printing
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or parallel port CD-ROM/disk support.
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To compile this driver as a module, choose M here: the
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module will be called ppdev.
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If unsure, say N.
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source "drivers/tty/hvc/Kconfig"
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config VIRTIO_CONSOLE
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tristate "Virtio console"
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depends on VIRTIO && TTY
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select HVC_DRIVER
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help
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Virtio console for use with hypervisors.
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Also serves as a general-purpose serial device for data
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transfer between the guest and host. Character devices at
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/dev/vportNpn will be created when corresponding ports are
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found, where N is the device number and n is the port number
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within that device. If specified by the host, a sysfs
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attribute called 'name' will be populated with a name for
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the port which can be used by udev scripts to create a
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symlink to the device.
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config IBM_BSR
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tristate "IBM POWER Barrier Synchronization Register support"
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depends on PPC_PSERIES
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help
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This devices exposes a hardware mechanism for fast synchronization
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of threads across a large system which avoids bouncing a cacheline
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between several cores on a system
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config POWERNV_OP_PANEL
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tristate "IBM POWERNV Operator Panel Display support"
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depends on PPC_POWERNV
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default m
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help
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If you say Y here, a special character device node, /dev/op_panel,
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will be created which exposes the operator panel display on IBM
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Power Systems machines with FSPs.
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If you don't require access to the operator panel display from user
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space, say N.
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If unsure, say M here to build it as a module called powernv-op-panel.
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source "drivers/char/ipmi/Kconfig"
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config DS1620
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tristate "NetWinder thermometer support"
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depends on ARCH_NETWINDER
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help
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Say Y here to include support for the thermal management hardware
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found in the NetWinder. This driver allows the user to control the
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temperature set points and to read the current temperature.
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It is also possible to say M here to build it as a module (ds1620)
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It is recommended to be used on a NetWinder, but it is not a
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necessity.
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config NWBUTTON
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tristate "NetWinder Button"
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depends on ARCH_NETWINDER
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---help---
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If you say Y here and create a character device node /dev/nwbutton
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with major and minor numbers 10 and 158 ("man mknod"), then every
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time the orange button is pressed a number of times, the number of
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times the button was pressed will be written to that device.
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This is most useful for applications, as yet unwritten, which
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perform actions based on how many times the button is pressed in a
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row.
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Do not hold the button down for too long, as the driver does not
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alter the behaviour of the hardware reset circuitry attached to the
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button; it will still execute a hard reset if the button is held
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down for longer than approximately five seconds.
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To compile this driver as a module, choose M here: the
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module will be called nwbutton.
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Most people will answer Y to this question and "Reboot Using Button"
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below to be able to initiate a system shutdown from the button.
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config NWBUTTON_REBOOT
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bool "Reboot Using Button"
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depends on NWBUTTON
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help
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If you say Y here, then you will be able to initiate a system
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shutdown and reboot by pressing the orange button a number of times.
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The number of presses to initiate the shutdown is two by default,
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but this can be altered by modifying the value of NUM_PRESSES_REBOOT
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in nwbutton.h and recompiling the driver or, if you compile the
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driver as a module, you can specify the number of presses at load
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time with "insmod button reboot_count=<something>".
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config NWFLASH
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tristate "NetWinder flash support"
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depends on ARCH_NETWINDER
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---help---
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If you say Y here and create a character device /dev/flash with
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major 10 and minor 160 you can manipulate the flash ROM containing
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the NetWinder firmware. Be careful as accidentally overwriting the
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flash contents can render your computer unbootable. On no account
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allow random users access to this device. :-)
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To compile this driver as a module, choose M here: the
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module will be called nwflash.
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If you're not sure, say N.
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source "drivers/char/hw_random/Kconfig"
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config NVRAM
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tristate "/dev/nvram support"
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depends on ATARI || X86 || GENERIC_NVRAM
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---help---
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If you say Y here and create a character special file /dev/nvram
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with major number 10 and minor number 144 using mknod ("man mknod"),
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you get read and write access to the extra bytes of non-volatile
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memory in the real time clock (RTC), which is contained in every PC
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and most Ataris. The actual number of bytes varies, depending on the
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nvram in the system, but is usually 114 (128-14 for the RTC).
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This memory is conventionally called "CMOS RAM" on PCs and "NVRAM"
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on Ataris. /dev/nvram may be used to view settings there, or to
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change them (with some utility). It could also be used to frequently
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save a few bits of very important data that may not be lost over
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power-off and for which writing to disk is too insecure. Note
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however that most NVRAM space in a PC belongs to the BIOS and you
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should NEVER idly tamper with it. See Ralf Brown's interrupt list
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for a guide to the use of CMOS bytes by your BIOS.
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On Atari machines, /dev/nvram is always configured and does not need
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to be selected.
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To compile this driver as a module, choose M here: the
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module will be called nvram.
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#
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# These legacy RTC drivers just cause too many conflicts with the generic
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# RTC framework ... let's not even try to coexist any more.
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#
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if RTC_LIB=n
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config RTC
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tristate "Enhanced Real Time Clock Support (legacy PC RTC driver)"
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depends on ALPHA || (MIPS && MACH_LOONGSON64)
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---help---
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If you say Y here and create a character special file /dev/rtc with
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major number 10 and minor number 135 using mknod ("man mknod"), you
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will get access to the real time clock (or hardware clock) built
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into your computer.
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Every PC has such a clock built in. It can be used to generate
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signals from as low as 1Hz up to 8192Hz, and can also be used
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as a 24 hour alarm. It reports status information via the file
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/proc/driver/rtc and its behaviour is set by various ioctls on
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/dev/rtc.
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If you run Linux on a multiprocessor machine and said Y to
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"Symmetric Multi Processing" above, you should say Y here to read
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and set the RTC in an SMP compatible fashion.
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If you think you have a use for such a device (such as periodic data
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sampling), then say Y here, and read <file:Documentation/rtc.txt>
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for details.
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To compile this driver as a module, choose M here: the
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module will be called rtc.
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config JS_RTC
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tristate "Enhanced Real Time Clock Support"
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depends on SPARC32 && PCI
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---help---
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If you say Y here and create a character special file /dev/rtc with
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major number 10 and minor number 135 using mknod ("man mknod"), you
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will get access to the real time clock (or hardware clock) built
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into your computer.
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Every PC has such a clock built in. It can be used to generate
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signals from as low as 1Hz up to 8192Hz, and can also be used
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as a 24 hour alarm. It reports status information via the file
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/proc/driver/rtc and its behaviour is set by various ioctls on
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/dev/rtc.
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If you think you have a use for such a device (such as periodic data
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sampling), then say Y here, and read <file:Documentation/rtc.txt>
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for details.
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To compile this driver as a module, choose M here: the
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module will be called js-rtc.
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config EFI_RTC
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bool "EFI Real Time Clock Services"
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depends on IA64
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endif # RTC_LIB
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config DTLK
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tristate "Double Talk PC internal speech card support"
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depends on ISA
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help
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This driver is for the DoubleTalk PC, a speech synthesizer
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manufactured by RC Systems (<http://www.rcsys.com/>). It is also
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called the `internal DoubleTalk'.
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To compile this driver as a module, choose M here: the
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module will be called dtlk.
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config XILINX_HWICAP
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tristate "Xilinx HWICAP Support"
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depends on XILINX_VIRTEX || MICROBLAZE
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help
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This option enables support for Xilinx Internal Configuration
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Access Port (ICAP) driver. The ICAP is used on Xilinx Virtex
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FPGA platforms to partially reconfigure the FPGA at runtime.
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If unsure, say N.
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config R3964
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tristate "Siemens R3964 line discipline"
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depends on TTY && BROKEN
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---help---
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This driver allows synchronous communication with devices using the
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Siemens R3964 packet protocol. Unless you are dealing with special
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hardware like PLCs, you are unlikely to need this.
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To compile this driver as a module, choose M here: the
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module will be called n_r3964.
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If unsure, say N.
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config APPLICOM
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tristate "Applicom intelligent fieldbus card support"
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depends on PCI
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---help---
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This driver provides the kernel-side support for the intelligent
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fieldbus cards made by Applicom International. More information
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about these cards can be found on the WWW at the address
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<http://www.applicom-int.com/>, or by email from David Woodhouse
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<dwmw2@infradead.org>.
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To compile this driver as a module, choose M here: the
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module will be called applicom.
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If unsure, say N.
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config SONYPI
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tristate "Sony Vaio Programmable I/O Control Device support"
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depends on X86_32 && PCI && INPUT
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---help---
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This driver enables access to the Sony Programmable I/O Control
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Device which can be found in many (all ?) Sony Vaio laptops.
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If you have one of those laptops, read
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<file:Documentation/laptops/sonypi.txt>, and say Y or M here.
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To compile this driver as a module, choose M here: the
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module will be called sonypi.
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config GPIO_TB0219
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tristate "TANBAC TB0219 GPIO support"
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depends on TANBAC_TB022X
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select GPIO_VR41XX
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source "drivers/char/pcmcia/Kconfig"
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config MWAVE
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tristate "ACP Modem (Mwave) support"
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depends on X86 && TTY
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select SERIAL_8250
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---help---
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The ACP modem (Mwave) for Linux is a WinModem. It is composed of a
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kernel driver and a user level application. Together these components
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support direct attachment to public switched telephone networks (PSTNs)
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and support selected world wide countries.
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This version of the ACP Modem driver supports the IBM Thinkpad 600E,
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600, and 770 that include on board ACP modem hardware.
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The modem also supports the standard communications port interface
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(ttySx) and is compatible with the Hayes AT Command Set.
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The user level application needed to use this driver can be found at
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the IBM Linux Technology Center (LTC) web site:
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<http://www.ibm.com/linux/ltc/>.
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If you own one of the above IBM Thinkpads which has the Mwave chipset
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in it, say Y.
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To compile this driver as a module, choose M here: the
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module will be called mwave.
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config SCx200_GPIO
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tristate "NatSemi SCx200 GPIO Support"
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depends on SCx200
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select NSC_GPIO
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help
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Give userspace access to the GPIO pins on the National
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Semiconductor SCx200 processors.
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If compiled as a module, it will be called scx200_gpio.
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config PC8736x_GPIO
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tristate "NatSemi PC8736x GPIO Support"
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depends on X86_32 && !UML
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default SCx200_GPIO # mostly N
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select NSC_GPIO # needed for support routines
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help
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Give userspace access to the GPIO pins on the National
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Semiconductor PC-8736x (x=[03456]) SuperIO chip. The chip
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has multiple functional units, inc several managed by
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hwmon/pc87360 driver. Tested with PC-87366
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If compiled as a module, it will be called pc8736x_gpio.
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config NSC_GPIO
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tristate "NatSemi Base GPIO Support"
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depends on X86_32
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# selected by SCx200_GPIO and PC8736x_GPIO
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# what about 2 selectors differing: m != y
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help
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Common support used (and needed) by scx200_gpio and
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pc8736x_gpio drivers. If those drivers are built as
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modules, this one will be too, named nsc_gpio
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config RAW_DRIVER
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tristate "RAW driver (/dev/raw/rawN)"
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depends on BLOCK
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help
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The raw driver permits block devices to be bound to /dev/raw/rawN.
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Once bound, I/O against /dev/raw/rawN uses efficient zero-copy I/O.
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See the raw(8) manpage for more details.
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Applications should preferably open the device (eg /dev/hda1)
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with the O_DIRECT flag.
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config MAX_RAW_DEVS
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int "Maximum number of RAW devices to support (1-65536)"
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depends on RAW_DRIVER
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range 1 65536
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default "256"
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help
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The maximum number of RAW devices that are supported.
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Default is 256. Increase this number in case you need lots of
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raw devices.
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config HPET
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bool "HPET - High Precision Event Timer" if (X86 || IA64)
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default n
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depends on ACPI
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help
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If you say Y here, you will have a miscdevice named "/dev/hpet/". Each
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open selects one of the timers supported by the HPET. The timers are
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non-periodic and/or periodic.
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config HPET_MMAP
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bool "Allow mmap of HPET"
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default y
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depends on HPET
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help
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If you say Y here, user applications will be able to mmap
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the HPET registers.
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config HPET_MMAP_DEFAULT
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bool "Enable HPET MMAP access by default"
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default y
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depends on HPET_MMAP
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help
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In some hardware implementations, the page containing HPET
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registers may also contain other things that shouldn't be
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exposed to the user. This option selects the default (if
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kernel parameter hpet_mmap is not set) user access to the
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registers for applications that require it.
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config HANGCHECK_TIMER
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tristate "Hangcheck timer"
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depends on X86 || IA64 || PPC64 || S390
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help
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The hangcheck-timer module detects when the system has gone
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out to lunch past a certain margin. It can reboot the system
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or merely print a warning.
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config UV_MMTIMER
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tristate "UV_MMTIMER Memory mapped RTC for SGI UV"
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depends on X86_UV
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default m
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help
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The uv_mmtimer device allows direct userspace access to the
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UV system timer.
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source "drivers/char/tpm/Kconfig"
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config TELCLOCK
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tristate "Telecom clock driver for ATCA SBC"
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depends on X86
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default n
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help
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The telecom clock device is specific to the MPCBL0010 and MPCBL0050
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ATCA computers and allows direct userspace access to the
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configuration of the telecom clock configuration settings. This
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device is used for hardware synchronization across the ATCA backplane
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fabric. Upon loading, the driver exports a sysfs directory,
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/sys/devices/platform/telco_clock, with a number of files for
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controlling the behavior of this hardware.
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config DEVPORT
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bool "/dev/port character device"
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depends on ISA || PCI
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default y
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help
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Say Y here if you want to support the /dev/port device. The /dev/port
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device is similar to /dev/mem, but for I/O ports.
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source "drivers/s390/char/Kconfig"
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source "drivers/char/xillybus/Kconfig"
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config ADI
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tristate "SPARC Privileged ADI driver"
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depends on SPARC64
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default m
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help
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SPARC M7 and newer processors utilize ADI (Application Data
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Integrity) to version and protect memory. This driver provides
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read/write access to the ADI versions for privileged processes.
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This feature is also known as MCD (Memory Corruption Detection)
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and SSM (Silicon Secured Memory). Intended consumers of this
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driver include crash and makedumpfile.
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endmenu
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config RANDOM_TRUST_CPU
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bool "Trust the CPU manufacturer to initialize Linux's CRNG"
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depends on X86 || S390 || PPC
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default n
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help
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Assume that CPU manufacturer (e.g., Intel or AMD for RDSEED or
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RDRAND, IBM for the S390 and Power PC architectures) is trustworthy
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for the purposes of initializing Linux's CRNG. Since this is not
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something that can be independently audited, this amounts to trusting
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that CPU manufacturer (perhaps with the insistence or mandate
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of a Nation State's intelligence or law enforcement agencies)
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has not installed a hidden back door to compromise the CPU's
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random number generation facilities. This can also be configured
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at boot with "random.trust_cpu=on/off".
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config RANDOM_TRUST_BOOTLOADER
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bool "Trust the bootloader to initialize Linux's CRNG"
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help
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Some bootloaders can provide entropy to increase the kernel's initial
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device randomness. Say Y here to assume the entropy provided by the
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booloader is trustworthy so it will be added to the kernel's entropy
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pool. Otherwise, say N here so it will be regarded as device input that
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only mixes the entropy pool.
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