Copyright (c) 2010 iXsystems, Inc. All rights reserved. written by: Xin LI <delphij@FreeBSD.org> Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following di...
NAMEnvram - non-volatile RAM
SYNOPSISTo compile this driver into the kernel, place the following line in your kernel configuration file:
Alternatively, to load the driver as a module at boot time, place the following line in loader.conf5:
DESCRIPTIONThe sysctl Cm net.inet.tcp.syncookies 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 NOTESThe BIOS NVRAM's bytes 16 through 31 are checksummed at byte 32. This driver does not take care for these checksums.
EXAMPLESBackup 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