Nvramtool

lxbios

Lxbios is a utility for reading/writing LinuxBIOS parameters and displaying information from the LinuxBIOS table in CMOS. The program works only on x86-based Linux systems that use LinuxBIOS. It can be downloaded here.

Running lxbios on a system running LinuxBIOS would yield a result like this:

 # ./lxbios -a
 boot_option = Fallback
 last_boot = Fallback
 ECC_memory = Disable
 baud_rate = 115200
 hw_scrubber = Enable
 interleave_chip_selects = Enable
 max_mem_clock = 100Mhz
 dual_core = Enable
 power_on_after_fail = Enable
 debug_level = Spew
 boot_first = HDD
 boot_second = Network
 boot_third = Floppy
 boot_index = 0xe
 boot_countdown = 0xfa
 slow_cpu = off
 nmi = Enable
 iommu = Enable
 lxbios: Can not read LinuxBIOS parameter user_data because layout info specifies CMOS area that is too wide.

Things to know

1. LinuxBIOS will ignore the CMOS table if the checksum is incorrect, and will fallback to its hardcoded defaults.

2. LinuxBIOS does not initialize the CMOS LinuxBIOS table to default values. In other words, until you set values with the lxbios tool, your CMOS table will have an incorrect checksum, and will simply be ignored

3. Not all of the fields that lxbios can set are used by LinuxBIOS on every mainboard.

4. Some of the fields are used by payloads - for instance all the fields that start with 'boot_' in the list above. FILO does not use those fields currently, but Etherboot does (someone confirm this please!).