# 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 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 TTY_PRINTK_LEVEL
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depends on TTY_PRINTK
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int "ttyprintk log level (1-7)"
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range 1 7
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default "6"
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help
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Printk log level to use for ttyprintk messages.
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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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<https://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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config VIRTIO_CONSOLE
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tristate "Virtio console"
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depends on TTY
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select HVC_DRIVER
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select VIRTIO
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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 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 (<https://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 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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<https://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/admin-guide/laptops/sonypi.rst>, 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 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 NVRAM
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tristate "/dev/nvram support"
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depends on X86 || HAVE_ARCH_NVRAM_OPS
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default M68K || PPC
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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 non-volatile memory.
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/dev/nvram may be used to view settings in NVRAM or to change them
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(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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This memory is conventionally called "NVRAM" on PowerPC machines,
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"CMOS RAM" on PCs, "NVRAM" on Ataris and "PRAM" on Macintoshes.
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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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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 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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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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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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config RANDOM_TRUST_CPU
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bool "Initialize RNG using CPU RNG instructions"
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default y
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depends on ARCH_RANDOM
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help
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Initialize the RNG using random numbers supplied by the CPU's
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RNG instructions (e.g. RDRAND), if supported and available. These
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random numbers are never used directly, but are rather hashed into
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the main input pool, and this happens regardless of whether or not
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this option is enabled. Instead, this option controls whether the
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they are credited and hence can initialize the RNG. Additionally,
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other sources of randomness are always used, regardless of this
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setting. Enabling this implies trusting that the CPU can supply high
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quality and non-backdoored random numbers.
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Say Y here unless you have reason to mistrust your CPU or believe
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its RNG facilities may be faulty. This may also be configured at
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boot time with "random.trust_cpu=on/off".
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config RANDOM_TRUST_BOOTLOADER
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bool "Initialize RNG using bootloader-supplied seed"
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default y
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help
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Initialize the RNG using a seed supplied by the bootloader or boot
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environment (e.g. EFI or a bootloader-generated device tree). This
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seed is not used directly, but is rather hashed into the main input
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pool, and this happens regardless of whether or not this option is
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enabled. Instead, this option controls whether the seed is credited
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and hence can initialize the RNG. Additionally, other sources of
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randomness are always used, regardless of this setting. Enabling
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this implies trusting that the bootloader can supply high quality and
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non-backdoored seeds.
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Say Y here unless you have reason to mistrust your bootloader or
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believe its RNG facilities may be faulty. This may also be configured
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at boot time with "random.trust_bootloader=on/off".
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endmenu
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