NAME

     nvram — non-volatile RAM

SYNOPSIS

     To compile this driver into the kernel, place the following line in your kernel
     configuration file:

           device nvram

     Alternatively, to load the driver as a module at boot time, place the following line in
     loader.conf(5):

           nvram_load="YES"

DESCRIPTION

     The nvram driver provides access to BIOS configuration NVRAM on i386 and amd64 systems.

     PC motherboard uses a small non-volatile memory to store BIOS settings which is usually part
     of its clock chip and sometimes referred as “CMOS SRAM”.  This driver exposes bytes 14
     through 128 of the NVRAM, or a total of 114 bytes, at offset zero of the device file
     /dev/nvram.

     This driver is useful for cloning machines that shares the same hardware configuration and
     need same BIOS setting tweaks.

IMPLEMENTATION NOTES

     The BIOS NVRAM's bytes 16 through 31 are checksummed at byte 32.  This driver does not take
     care for these checksums.

EXAMPLES

     Backup existing BIOS NVRAM to nvram.bin:

           dd if=/dev/nvram of=nvram.bin

     Restore BIOS NVRAM from nvram.bin:

           dd if=nvram.bin of=/dev/nvram

SEE ALSO

     dd(1)

HISTORY

     The nvram device driver first appeared in FreeBSD 6.4.

AUTHORS

     The nvram device driver was written by Peter Wemm.  This manual page was written by Xin LI.