Difference between revisions of "LAR Design"
From coreboot
(→TODO) |
Hailfinger (Talk | contribs) |
||
| (5 intermediate revisions by 3 users not shown) | |||
| Line 1: | Line 1: | ||
| + | <div style="margin:0.5em 0; padding:0.5em; background:#ffd0d0; border:1px solid #aabbcc;"> | ||
| + | Please note that LAR is not used in coreboot v2 trunk (which has the alternative [[CBFS]]), but LAR is still used for coreboot v3. | ||
| + | </div> | ||
| + | |||
= Introduction = | = Introduction = | ||
| − | LAR is the | + | <div style="margin:0.5em 0; padding:0.5em; background:#ffd0d0; border:1px solid #aabbcc;"> |
| + | Please note that this page is incomplete and outdated, the LAR documentation in the coreboot v3 source tree (including code comments) lists the current features and has up-to-date design documentation. | ||
| + | </div> | ||
| + | LAR is the coreboot archiver. It is a small utility that we use to create and change coreboot images and their modules. | ||
It is a simple archiver, similar to cpio, ar or tar. | It is a simple archiver, similar to cpio, ar or tar. | ||
| Line 12: | Line 19: | ||
For a usage example see example.c. | For a usage example see example.c. | ||
| − | For questions contact | + | For questions contact [mailto:stepan@coresystems.de Stefan Reinauer]. |
| − | + | ||
= Usage = | = Usage = | ||
| Line 46: | Line 52: | ||
Headers have to be 16 byte aligned. | Headers have to be 16 byte aligned. | ||
| − | + | Data blocks have to be 16 byte aligned. | |
|----------------------------| | |----------------------------| | ||
| magic (8 bytes) | | | magic (8 bytes) | | ||
|----------------------------| | |----------------------------| | ||
| − | | length (4 bytes) | + | | compressed length (4 bytes)| |
| + | |----------------------------| | ||
| + | | real length (4 bytes) | | ||
|----------------------------| | |----------------------------| | ||
| checksum (4 bytes) | | | checksum (4 bytes) | | ||
| + | |----------------------------| | ||
| + | | chksum compressed blob (4b)| | ||
|----------------------------| | |----------------------------| | ||
| offset to blob (4 bytes) | | | offset to blob (4 bytes) | | ||
|----------------------------| | |----------------------------| | ||
| − | | | + | | compression id (4 bytes) | |
| + | |----------------------------| | ||
| + | | "path",\0 (16b aligned) | | ||
|----------------------------| | |----------------------------| | ||
| blob (aligned to 16 bytes) | | | blob (aligned to 16 bytes) | | ||
|----------------------------| | |----------------------------| | ||
| + | * compressed length means: length of blob | ||
| + | * real length means: size of the uncompressed blob | ||
| + | * checksum covers: header and blob, with "checksum" and "checksum compressed blob" set to 0 | ||
| + | * checksum compressed blob covers: the uncompressed data (no headers) | ||
= TODO = | = TODO = | ||
| Line 71: | Line 87: | ||
= Discussion = | = Discussion = | ||
| − | Patrick | + | Patrick Georgi and Stefan Reinauer discussed extending LAR so that it handles a MANIFEST file. |
This file will list all existing files, and their current compression. If a file is in the MANIFEST, it's compression status will not be changed. This feature is required for making sure that initram is not compressed. | This file will list all existing files, and their current compression. If a file is in the MANIFEST, it's compression status will not be changed. This feature is required for making sure that initram is not compressed. | ||
| Line 77: | Line 93: | ||
MANIFEST will describe | MANIFEST will describe | ||
* compression of files | * compression of files | ||
| − | * size of the unpacked image | + | * size of the unpacked image (optional on parse-time, to make it easier for "lar c" users) |
* bootblock name | * bootblock name | ||
* other metadata? | * other metadata? | ||
| + | |||
| + | Example: | ||
| + | * normal/initram=../../build/coreboot.initram * none | ||
| + | means: the file "normal/initram" inside the lar file will be created from "../../build/coreboot.initram", with "none" compression. size isn't given and taken from the existing file | ||
Some syntax examples | Some syntax examples | ||
| − | $ lar x | + | $ lar x coreboot.rom # create coreboot/* and coreboot/MANIFEST |
| − | $ lar c | + | $ lar c coreboot.rom coreboot/ # looks for coreboot/MANIFEST |
| − | $ lar x | + | $ lar x coreboot.rom # image without payload |
$ cp payload.bin | $ cp payload.bin | ||
| − | $ lar c | + | $ lar c coreboot.rom coreboot/ -s 512K |
$ # creates image, overiding size to 512K | $ # creates image, overiding size to 512K | ||
Latest revision as of 21:13, 7 November 2009
Please note that LAR is not used in coreboot v2 trunk (which has the alternative CBFS), but LAR is still used for coreboot v3.
Contents |
[edit] Introduction
Please note that this page is incomplete and outdated, the LAR documentation in the coreboot v3 source tree (including code comments) lists the current features and has up-to-date design documentation.
LAR is the coreboot archiver. It is a small utility that we use to create and change coreboot images and their modules.
It is a simple archiver, similar to cpio, ar or tar.
Design goals were
- minimum overhead - maximum fault tolerance - simplicity
For a usage example see example.c.
For questions contact Stefan Reinauer.
[edit] Usage
Create archive archive.lar containing files file1 ... fileN:
$ lar c archive.lar file1 ... fileN
Extract files from archive.lar:
$ lar x archive.lar [file1 ... fileN]
List files in archive:
$ lar l archive.lar
[edit] Archive format
The rough format is:
|--------------| | header | |--------------| | data | |--------------| | header | |--------------| | data | |--------------| ...
Headers have to be 16 byte aligned.
Data blocks have to be 16 byte aligned.
|----------------------------| | magic (8 bytes) | |----------------------------| | compressed length (4 bytes)| |----------------------------| | real length (4 bytes) | |----------------------------| | checksum (4 bytes) | |----------------------------| | chksum compressed blob (4b)| |----------------------------| | offset to blob (4 bytes) | |----------------------------| | compression id (4 bytes) | |----------------------------| | "path",\0 (16b aligned) | |----------------------------| | blob (aligned to 16 bytes) | |----------------------------|
- compressed length means: length of blob
- real length means: size of the uncompressed blob
- checksum covers: header and blob, with "checksum" and "checksum compressed blob" set to 0
- checksum compressed blob covers: the uncompressed data (no headers)
[edit] TODO
- Reading flash layouts
- This does not enforce any alignment yet
- Alignment enforcing will be optional
[edit] Discussion
Patrick Georgi and Stefan Reinauer discussed extending LAR so that it handles a MANIFEST file.
This file will list all existing files, and their current compression. If a file is in the MANIFEST, it's compression status will not be changed. This feature is required for making sure that initram is not compressed.
MANIFEST will describe
- compression of files
- size of the unpacked image (optional on parse-time, to make it easier for "lar c" users)
- bootblock name
- other metadata?
Example:
- normal/initram=../../build/coreboot.initram * none
means: the file "normal/initram" inside the lar file will be created from "../../build/coreboot.initram", with "none" compression. size isn't given and taken from the existing file
Some syntax examples
$ lar x coreboot.rom # create coreboot/* and coreboot/MANIFEST
$ lar c coreboot.rom coreboot/ # looks for coreboot/MANIFEST
$ lar x coreboot.rom # image without payload $ cp payload.bin $ lar c coreboot.rom coreboot/ -s 512K $ # creates image, overiding size to 512K
