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CONFIG_NVRAM: /dev/nvram support

General informations

The Linux kernel configuration item CONFIG_NVRAM has multiple definitions:

/dev/nvram support found in drivers/char/Kconfig

The configuration item CONFIG_NVRAM:

Help text

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 extra bytes of non-volatile memory in the real time clock (RTC), which is contained in every PC and most Ataris. The actual number of bytes varies, depending on the nvram in the system, but is usually 114 (128-14 for the RTC).

This memory is conventionally called "CMOS RAM" on PCs and "NVRAM" on Ataris. /dev/nvram may be used to view settings there, 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.

On Atari machines, /dev/nvram is always configured and does not need to be selected.

To compile this driver as a module, choose M here: the module will be called nvram.

found in arch/m68k/Kconfig

The configuration item CONFIG_NVRAM:

Help text

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 50 bytes of non-volatile memory in the real time clock (RTC), which is contained in every PC and most Ataris.

This memory is conventionally called "CMOS RAM" on PCs and "NVRAM" on Ataris. /dev/nvram may be used to view settings there, 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.

On Atari machines, /dev/nvram is always configured and does not need to be selected.

To compile this driver as a module, choose M here: the module will be called nvram.

Hardware

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