CMOS.layout guide

From coreboot
Revision as of 16:50, 25 January 2011 by MBertens (Talk | contribs)

Jump to: navigation, search

CMOS layout

This page explain the workings of the CMOS layout file. The CMOS layout file can be linked into a board specific environment. By creating the cmos.layout file in the board directory. and set the HAVE_OPTION_TABLE in the Kconfig file of the board.

The CMOS layout file must contain the following sections;

  • entries
  • enumerations
  • checksums

The hash (#) character is the comment prefix, all characters until the eof of line are treated as comment.

entries section

enumerations section

checksums section

The checksums section has one variable with three parameters;

 checksum <startbit> <endbit> <start-of-checksumbit>

The <startbit> parameter is the bit position where the calculation of the checksum starts from.

The <endbit> parameter is the bit position there the calculation of the checksum starts on.

The <start-of-checksumbit> parameter is the bit position there the checksum will be stored, there must be space for 16 bits of checksum data.

Example;

 checksum 392 983 984