Difference between revisions of "Nvramtool"

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{{GPL}}
 
{{GPL}}
Lxbios is a utility for reading/writing LinuxBIOS parameters and displaying information from the LinuxBIOS table in CMOS.
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Lxbios is a utility for reading/writing coreboot parameters and displaying information from the coreboot table in CMOS.
  
The program works only on x86-based Linux systems that use LinuxBIOS.
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The program works only on x86-based Linux systems that use coreboot.
  
 
It can be downloaded from http://www.llnl.gov/linux/lxbios/lxbios.html.
 
It can be downloaded from http://www.llnl.gov/linux/lxbios/lxbios.html.
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== Using lxbios ==
 
== Using lxbios ==
  
Running lxbios on a system running LinuxBIOS would yield a result like this:
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Running lxbios on a system running coreboot would yield a result like this:
  
 
   # ./lxbios -a
 
   # ./lxbios -a
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   nmi = Enable
 
   nmi = Enable
 
   iommu = Enable
 
   iommu = Enable
   lxbios: Can not read LinuxBIOS parameter user_data because layout info specifies CMOS area that is too wide.
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   lxbios: Can not read coreboot parameter user_data because layout info specifies CMOS area that is too wide.
  
 
== Things to know ==
 
== Things to know ==
  
# LinuxBIOS will ignore the CMOS table if the checksum is incorrect, and will fallback to its hardcoded defaults.
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# coreboot 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.
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# coreboot does not initialize the CMOS/NVRAM 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.
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# Not all of the fields that lxbios can set are used by coreboot 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!).
 
# 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!).

Revision as of 14:52, 15 January 2008

GNU head This work is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or any later version. This work is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

Lxbios is a utility for reading/writing coreboot parameters and displaying information from the coreboot table in CMOS.

The program works only on x86-based Linux systems that use coreboot.

It can be downloaded from http://www.llnl.gov/linux/lxbios/lxbios.html.

Using lxbios

Running lxbios on a system running coreboot 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 coreboot parameter user_data because layout info specifies CMOS area that is too wide.

Things to know

  1. coreboot will ignore the CMOS table if the checksum is incorrect, and will fallback to its hardcoded defaults.
  2. coreboot does not initialize the CMOS/NVRAM 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 coreboot 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!).