CMOS.layout guide: Difference between revisions
| Line 76: | Line 76: | ||
'''entries''' | '''entries''' | ||
#start-bit length config config-ID name | #start-bit length config config-ID name | ||
0 384 r 0 reserved_memory | 0 384 r 0 reserved_memory | ||
| Line 102: | Line 102: | ||
# Reserve the extended AMD configuration registers | # Reserve the extended AMD configuration registers | ||
1000 24 r 0 amd_reserved | 1000 24 r 0 amd_reserved | ||
'''enumerations''' | '''enumerations''' | ||
#ID value text | #ID value text | ||
# for ECC_memory, hw_scrubber, interleave_chip_selects, power_on_after_fail, nmi, iommu | # for ECC_memory, hw_scrubber, interleave_chip_selects, power_on_after_fail, nmi, iommu | ||
| Line 151: | Line 151: | ||
9 6 25.0% | 9 6 25.0% | ||
9 7 12.5% | 9 7 12.5% | ||
'''checksums''' | '''checksums''' | ||
checksum 392 983 984 | checksum 392 983 984 | ||
Revision as of 17:19, 25 January 2011
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
This section defined all the variables used within coreboot. Each line consists out of the following parameters;
<start-bit> <bit-length> <config> <config-id> <parameter-name>
The parameter <start-bit> is the start position is bit position where the parameter get stored.
The parameter <bit-length> is the length in bits of the parameter.
The parameter <config> indicates the type of parameter, currently there are three known types;
- r = register
- e = enumeration
- h = ?
The parameter <config-id> is used when the <config> is set to 'e', than there must be at least one item in the enumeration section. The <config-id> does not have to be unique, a <config-id> in the enumeration section can be used for different entries.
The parameter <parameter-name> is the name the coreboot retrieval and storage functions will refer to.
Example:
0 384 r 0 reserved_memory 384 3 e 5 baud_rate 487 1 e 1 power_on_after_fail
enumerations section
Each line in the the enumerations section is contructed as follows;
<config-id> <value> <label>
The parameter <config-id> is the same value as the <config-id> from the entries section.
The parameter <value> is the value that get stored at the bit location defined in the entries section, where that config-id is being used.
The parameter <label> is the label for displaying in the the presentation layer.
Example;
1 0 Disable 1 1 Enable 5 0 115200 5 1 57600 5 2 38400 5 3 19200 5 4 9600 5 5 4800 5 6 2400 5 7 1200
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
Example cmos.layout file
entries #start-bit length config config-ID name 0 384 r 0 reserved_memory 384 1 e 4 boot_option 385 1 e 4 last_boot 386 1 e 1 ECC_memory 388 4 r 0 reboot_bits 392 3 e 5 baud_rate 395 1 e 1 hw_scrubber 396 1 e 1 interleave_chip_selects 397 2 e 8 max_mem_clock 399 1 e 2 multi_core 400 1 e 1 power_on_after_fail 412 4 e 6 debug_level 416 4 e 7 boot_first 420 4 e 7 boot_second 424 4 e 7 boot_third 428 4 h 0 boot_index 432 8 h 0 boot_countdown 440 4 e 9 slow_cpu 444 1 e 1 nmi 445 1 e 1 iommu 728 256 h 0 user_data 984 16 h 0 check_sum # Reserve the extended AMD configuration registers 1000 24 r 0 amd_reserved enumerations #ID value text # for ECC_memory, hw_scrubber, interleave_chip_selects, power_on_after_fail, nmi, iommu 1 0 Disable 1 1 Enable # multi_core 2 0 Enable 2 1 Disable # boot_option, last_boot 4 0 Fallback 4 1 Normal # baud_rate 5 0 115200 5 1 57600 5 2 38400 5 3 19200 5 4 9600 5 5 4800 5 6 2400 5 7 1200 # debug_level 6 6 Notice 6 7 Info 6 8 Debug 6 9 Spew # boot_first, boot_second, boot_third 7 0 Network 7 1 HDD 7 2 Floppy 7 8 Fallback_Network 7 9 Fallback_HDD 7 10 Fallback_Floppy 7 3 ROM # max_mem_clock 8 0 DDR400 8 1 DDR333 8 2 DDR266 8 3 DDR200 # slow_cpu 9 0 off 9 1 87.5% 9 2 75.0% 9 3 62.5% 9 4 50.0% 9 5 37.5% 9 6 25.0% 9 7 12.5% checksums checksum 392 983 984