Nvramtool: Difference between revisions

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Lxbios is a utility for reading/writing LinuxBIOS parameters and displaying information from the LinuxBIOS table in CMOS.
'''nvramtool''' (previously known as '''lxbios''' and '''cmos_util''') is a utility for reading/writing coreboot parameters and displaying information from the coreboot table in CMOS/NVRAM.


The program works only on x86-based Linux systems that use LinuxBIOS.
The program is intended only for x86-based Linux systems that use coreboot, but can also be used for non-coreboot systems (e.g. for dumping all NVRAM bytes).


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


== Using lxbios ==
'''Manual Installation'''


Running lxbios on a system running LinuxBIOS would yield a result like this:
$ '''git clone http://review.coreboot.org/coreboot.git'''
$ '''cd coreboot/util/nvramtool'''
$ '''make'''
$ '''sudo make install''' (optional)


   # ./lxbios -a
'''Debian'''
 
$ '''sudo aptitude install nvramtool'''
 
== Using nvramtool ==
 
Running nvramtool on a system running coreboot would yield a result like this:
 
   $ '''./nvramtool -a'''
   boot_option = Fallback
   boot_option = Fallback
   last_boot = Fallback
   last_boot = Fallback
Line 28: Line 39:
   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.
   nvramtool: Can not read coreboot parameter user_data because layout info specifies CMOS area that is too wide.
 
== Commonly used CMOS/NVRAM options ==
 
=== coreboot v4 ===
 
{| border="0"
|- bgcolor="#6699dd"
! align="left" | Option
! align="left" | Used in
! align="left" | Comment
! align="left" | Possible values
|- bgcolor="#eeeeee"
| baud_rate
| src/pc80/serial.c
| The serial port BAUD rate setup by coreboot.
| 115200, 57600, 38400, 19200, 9600, 4800, 2400, 1200
|- bgcolor="#eeeeee"
| debug_level
| src/console/console.c
| The coreboot debugging level.
| Notice, Info, Debug, Spew
|- bgcolor="#eeeeee"
| ECC_memory
| src/northbridge/intel/e7520/raminit.c<br />src/northbridge/intel/e7525/raminit.c<br />src/northbridge/amd/amdk8/raminit.c<br />src/northbridge/amd/amdk8/raminit_f.c
|
| Enable, Disable
|- bgcolor="#eeeeee"
| interleave_chip_selects
| src/northbridge/amd/amdk8/raminit.c<br />src/northbridge/amd/amdk8/raminit_f.c
|
| Enable, Disable
|- bgcolor="#eeeeee"
| max_mem_clock
| src/northbridge/amd/amdk8/raminit.c<br />src/northbridge/amd/amdk8/raminit_f.c
|
| mainboard-dependent
|- bgcolor="#eeeeee"
| dual_core
| src/cpu/amd/model_fxx/init_cpus.c<br />src/cpu/amd/dualcore/dualcore.c<br />src/northbridge/amd/amdk8/coherent_ht.c<br />src/cpu/amd/dualcore/amd_sibling.c<br />src/northbridge/amd/amdk8/northbridge.c
|
| Enable, Disable
|- bgcolor="#eeeeee"
| quad_core
| src/cpu/amd/quadcore/quadcore.c<br />src/cpu/amd/model_10xxx/init_cpus.c<br />src/cpu/amd/quadcore/amd_sibling.c<br />src/northbridge/amd/amdfam10/northbridge.c
|
|
|- bgcolor="#eeeeee"
| power_on_after_fail
| src/southbridge/amd/sb600/sb600_sm.c<br />src/southbridge/amd/amd8111/amd8111_acpi.c<br />src/southbridge/nvidia/ck804/ck804_lpc.c<br />src/southbridge/nvidia/mcp55/mcp55_lpc.c<br />src/southbridge/intel/i82801ca/i82801ca_lpc.c<br />src/southbridge/intel/esb6300/esb6300_lpc.c<br />src/southbridge/intel/i82801er/i82801er_lpc.c<br />src/southbridge/intel/i3100/i3100_lpc.c<br />src/southbridge/sis/sis966/sis966_lpc.c<br />src/superio/winbond/w83627ehg/superio.c<br />src/superio/winbond/w83627hf/superio.c
|
| Enable, Disable
|- bgcolor="#eeeeee"
| slow_cpu
| src/southbridge/amd/amd8111/amd8111_acpi.c<br />src/southbridge/nvidia/ck804/ck804_lpc.c<br />src/southbridge/nvidia/mcp55/mcp55_lpc.c<br />src/southbridge/sis/sis966/sis966_lpc.c
|
| off, 87.5%, 75.0%, 62.5%, 50.0%, 37.5%, 25.0%, 12.5%
|- bgcolor="#eeeeee"
| nmi
| src/southbridge/amd/sb600/sb600_sm.c<br />src/southbridge/amd/amd8111/amd8111_acpi.c<br />src/southbridge/amd/amd8111/amd8111_lpc.c<br />src/southbridge/amd/amd8131/amd8131_bridge.c<br />src/southbridge/broadcom/bcm5785/bcm5785_sb_pci_main.c<br />src/southbridge/nvidia/ck804/ck804_lpc.c<br />src/southbridge/nvidia/mcp55/mcp55_lpc.c<br />src/southbridge/intel/i82801ca/i82801ca_lpc.c<br />src/southbridge/intel/esb6300/esb6300_lpc.c<br />src/southbridge/intel/i82801er/i82801er_lpc.c<br />src/southbridge/intel/pxhd/pxhd_bridge.c<br />src/southbridge/intel/i82801xx/i82801xx_lpc.c<br />src/southbridge/intel/i3100/i3100_lpc.c<br />src/southbridge/intel/i82801dbm/i82801dbm_lpc.c<br />src/southbridge/sis/sis966/sis966_lpc.c
|
| Enable, Disable
|- bgcolor="#eeeeee"
| pxhd_bus_speed_100
| src/southbridge/intel/pxhd/pxhd_bridge.c
|
|
|- bgcolor="#eeeeee"
| hw_scrubber
| src/cpu/amd/model_fxx/model_fxx_init.c
|
|
|- bgcolor="#eeeeee"
| hyper_threading
| src/cpu/intel/hyperthreading/intel_sibling.c
|
|
|- bgcolor="#eeeeee"
| iommu
| src/northbridge/amd/amdk8/misc_control.c<br />src/northbridge/amd/amdfam10/misc_control.c
|
| Enable, Disable
|}
 
=== FILO 0.6 ===
 
{| border="0"
|- bgcolor="#6699dd"
! align="left" | Option
! align="left" | Used in
! align="left" | Comment
! align="left" | Possible values
|- bgcolor="#eeeeee"
| boot_devices
| main/grub/grub.c
|
|
|}
 
=== Etherboot 5.4.2 ===
 
{| border="0"
|- bgcolor="#6699dd"
! align="left" | Option
! align="left" | Used in
! align="left" | Comment
! align="left" | Possible values
|- bgcolor="#eeeeee"
| last_boot
| src/firmware/linuxbios/linuxbios.c
|
|
|- bgcolor="#eeeeee"
| boot_countdown
| src/firmware/linuxbios/linuxbios.c
|
|
|- bgcolor="#eeeeee"
| boot_index
| src/firmware/linuxbios/linuxbios.c
|
|
|- bgcolor="#eeeeee"
| boot_first
| src/firmware/linuxbios/linuxbios.c
|
|
|- bgcolor="#eeeeee"
| boot_second
| src/firmware/linuxbios/linuxbios.c
|
|
|- bgcolor="#eeeeee"
| boot_third
| src/firmware/linuxbios/linuxbios.c
|
|
|}


== Things to know ==
== Things to know ==


# LinuxBIOS will ignore the CMOS table if the checksum is incorrect, and will fallback to its hardcoded defaults.
* CMOS table default value are stored in a "src/mainboard/$(MAINBOARDDIR)/cmos.default" file, it is taken into account only if coreboot is built with "HAVE_CMOS_DEFAULT".
# LinuxBIOS does not initialize the CMOS LinuxBIOS table to default values. In other words, until you set values with the lxbios tool, your CMOS table will have an incorrect checksum, and will simply be ignored.
* If coreboot handle "cmos.default" and if the checksum in the CMOS/NVRAM is incorrect, coreboot will write all the default value and compute a correct checksum.
# Not all of the fields that lxbios can set are used by LinuxBIOS on every mainboard.
* for each board "src/mainboard/$(MAINBOARDDIR)/cmos.layout" list the parameters and their available values. Some board doesn't handle CMOS/NVRAM (HAVE_OPTION_TABLE is disabled). The file structure is explained in the [[CMOS.layout_guide]].
# 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!).
* If coreboot does not handle "cmos.default" the checksum is not taken into account and values are read even if the checksum is bad.
* Not all of the fields that nvramtool can set are used by coreboot on every mainboard.
* Some of the fields are used by [[payloads]] &mdash; for instance all the fields that start with '''boot_''' in the list above. [[FILO]] and [[Etherboot]] are two examples of bootloaders parsing NVRAM values (see their pages for a list of known variables).
 
== Old websites ==
 
The nvramtool tool is now maintained by the coreboot developers and this page is the main website of nvramtool. For reference, the following websites were previously used, but are now deprecated:
 
* http://www.llnl.gov/linux/lxbios/lxbios.html (dead)
* https://computing.llnl.gov/linux/lxbios.html (dead)
* http://sourceforge.net/projects/lxbios/
 
{{GPL}}

Latest revision as of 20:48, 6 September 2015

nvramtool (previously known as lxbios and cmos_util) is a utility for reading/writing coreboot parameters and displaying information from the coreboot table in CMOS/NVRAM.

The program is intended only for x86-based Linux systems that use coreboot, but can also be used for non-coreboot systems (e.g. for dumping all NVRAM bytes).

Installation

Manual Installation 

$ git clone http://review.coreboot.org/coreboot.git
$ cd coreboot/util/nvramtool
$ make
$ sudo make install (optional)

Debian 

$ sudo aptitude install nvramtool

Using nvramtool

Running nvramtool on a system running coreboot would yield a result like this: 

 $ ./nvramtool -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
 nvramtool: Can not read coreboot parameter user_data because layout info specifies CMOS area that is too wide.

Commonly used CMOS/NVRAM options

coreboot v4

Option Used in Comment Possible values
baud_rate src/pc80/serial.c The serial port BAUD rate setup by coreboot. 115200, 57600, 38400, 19200, 9600, 4800, 2400, 1200
debug_level src/console/console.c The coreboot debugging level. Notice, Info, Debug, Spew
ECC_memory src/northbridge/intel/e7520/raminit.c
src/northbridge/intel/e7525/raminit.c
src/northbridge/amd/amdk8/raminit.c
src/northbridge/amd/amdk8/raminit_f.c 		Enable, Disable
interleave_chip_selects src/northbridge/amd/amdk8/raminit.c
src/northbridge/amd/amdk8/raminit_f.c 		Enable, Disable
max_mem_clock src/northbridge/amd/amdk8/raminit.c
src/northbridge/amd/amdk8/raminit_f.c 		mainboard-dependent
dual_core src/cpu/amd/model_fxx/init_cpus.c
src/cpu/amd/dualcore/dualcore.c
src/northbridge/amd/amdk8/coherent_ht.c
src/cpu/amd/dualcore/amd_sibling.c
src/northbridge/amd/amdk8/northbridge.c 		Enable, Disable
quad_core src/cpu/amd/quadcore/quadcore.c
src/cpu/amd/model_10xxx/init_cpus.c
src/cpu/amd/quadcore/amd_sibling.c
src/northbridge/amd/amdfam10/northbridge.c
power_on_after_fail src/southbridge/amd/sb600/sb600_sm.c
src/southbridge/amd/amd8111/amd8111_acpi.c
src/southbridge/nvidia/ck804/ck804_lpc.c
src/southbridge/nvidia/mcp55/mcp55_lpc.c
src/southbridge/intel/i82801ca/i82801ca_lpc.c
src/southbridge/intel/esb6300/esb6300_lpc.c
src/southbridge/intel/i82801er/i82801er_lpc.c
src/southbridge/intel/i3100/i3100_lpc.c
src/southbridge/sis/sis966/sis966_lpc.c
src/superio/winbond/w83627ehg/superio.c
src/superio/winbond/w83627hf/superio.c 		Enable, Disable
slow_cpu src/southbridge/amd/amd8111/amd8111_acpi.c
src/southbridge/nvidia/ck804/ck804_lpc.c
src/southbridge/nvidia/mcp55/mcp55_lpc.c
src/southbridge/sis/sis966/sis966_lpc.c 		off, 87.5%, 75.0%, 62.5%, 50.0%, 37.5%, 25.0%, 12.5%
nmi src/southbridge/amd/sb600/sb600_sm.c
src/southbridge/amd/amd8111/amd8111_acpi.c
src/southbridge/amd/amd8111/amd8111_lpc.c
src/southbridge/amd/amd8131/amd8131_bridge.c
src/southbridge/broadcom/bcm5785/bcm5785_sb_pci_main.c
src/southbridge/nvidia/ck804/ck804_lpc.c
src/southbridge/nvidia/mcp55/mcp55_lpc.c
src/southbridge/intel/i82801ca/i82801ca_lpc.c
src/southbridge/intel/esb6300/esb6300_lpc.c
src/southbridge/intel/i82801er/i82801er_lpc.c
src/southbridge/intel/pxhd/pxhd_bridge.c
src/southbridge/intel/i82801xx/i82801xx_lpc.c
src/southbridge/intel/i3100/i3100_lpc.c
src/southbridge/intel/i82801dbm/i82801dbm_lpc.c
src/southbridge/sis/sis966/sis966_lpc.c 		Enable, Disable
pxhd_bus_speed_100 src/southbridge/intel/pxhd/pxhd_bridge.c
hw_scrubber src/cpu/amd/model_fxx/model_fxx_init.c
hyper_threading src/cpu/intel/hyperthreading/intel_sibling.c
iommu src/northbridge/amd/amdk8/misc_control.c
src/northbridge/amd/amdfam10/misc_control.c 		Enable, Disable

FILO 0.6

Option Used in Comment Possible values
boot_devices main/grub/grub.c

Etherboot 5.4.2

Option Used in Comment Possible values
last_boot src/firmware/linuxbios/linuxbios.c
boot_countdown src/firmware/linuxbios/linuxbios.c
boot_index src/firmware/linuxbios/linuxbios.c
boot_first src/firmware/linuxbios/linuxbios.c
boot_second src/firmware/linuxbios/linuxbios.c
boot_third src/firmware/linuxbios/linuxbios.c

Things to know

  • CMOS table default value are stored in a "src/mainboard/$(MAINBOARDDIR)/cmos.default" file, it is taken into account only if coreboot is built with "HAVE_CMOS_DEFAULT".
  • If coreboot handle "cmos.default" and if the checksum in the CMOS/NVRAM is incorrect, coreboot will write all the default value and compute a correct checksum.
  • for each board "src/mainboard/$(MAINBOARDDIR)/cmos.layout" list the parameters and their available values. Some board doesn't handle CMOS/NVRAM (HAVE_OPTION_TABLE is disabled). The file structure is explained in the CMOS.layout_guide.
  • If coreboot does not handle "cmos.default" the checksum is not taken into account and values are read even if the checksum is bad.
  • Not all of the fields that nvramtool 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 and Etherboot are two examples of bootloaders parsing NVRAM values (see their pages for a list of known variables).

Old websites

The nvramtool tool is now maintained by the coreboot developers and this page is the main website of nvramtool. For reference, the following websites were previously used, but are now deprecated:

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.
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