Nvramtool
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Documentation is now handled by the same processes we use for code: Add something to the Documentation/ directory in the coreboot repo, and it will be rendered to https://doc.coreboot.org/. Contributions welcome!
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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 from http://www.llnl.gov/linux/lxbios/lxbios.html.
Using lxbios
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
- LinuxBIOS will ignore the CMOS table if the checksum is incorrect, and will fallback to its hardcoded defaults.
- 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.
- Not all of the fields that lxbios can set are used by LinuxBIOS on every mainboard.
- 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!).