Difference between revisions of "Custom Linux Kernel Development"
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| + | These directories will be referred to as needed in this document. | ||
== Configuration == | == Configuration == | ||
| − | + | The kernel uses a configuration system that specifies how every aspect of the kernel is built. This configuration information is generated based on selections by the user as well as dependency information | |
Refer to configuration section in the kernel building document. Show how to add / remove options in the config. | Refer to configuration section in the kernel building document. Show how to add / remove options in the config. | ||
Revision as of 17:53, 29 December 2013
The ability to easily customize and expand any portion of the kernel is a feature of Linux that makes it very well suited for embedded systems development. In the embedded environment, specialized hardware, protocols, and systems may require a look into the kernel internals, custom configuration, feature additions, or driver development. This article aims to provide information on the most common kernel development tasks for EMAC OE Linux systems. In addition, the reader is pointed to additional sources for kernel development resources.
Before continuing, make sure that git tools are installed on your development machine, and review the Building the Linux Kernel document.
Contents
The Kernel Source
Source code for EMAC kernels is provided through our Git server. Refer to the documentation for your system to determine the correct source to use.
 | For this guide, the 2.6.30-at91 kernel tree will be used, which currently covers many of EMAC's SoM-based ARM products. |
Clone the Git Repository
To clone the git repository over anonymous HTTP, run the following commands:
developer@ldc:~$ git clone http://git.emacinc.com/public/source/linux-2.6.30-at91.git
Once the command has completed, the entire source should be contained in the linux-2.6.30-at91 directory. The master branch will be checked out automatically. Because EMAC uses the master branch for all releases, this is the correct branch to use, but other branches or tags may be checked out if directed or required.
Kernel Source Structure
Within the kernel source tree that was downloaded, you will see several directories. Table 1 gives a brief description of each of these directories.
| Directory name | Description |
|---|---|
arch |
Architecture-specific kernel code with subdirectories for each architecture |
block |
Block device driver code |
crypto |
Encryption support algorithms |
Documentation |
Text documentation files on the kernel and APIs |
drivers |
Device driver code, with a subdirectory structure for each device type |
firmware |
Code for building firmware required to communicate with devices |
fs |
File systems code |
include |
Include (header) files required to build the kernel code |
init |
Kernel initialization code |
ipc |
Interprocess communications code |
kernel |
Main internal kernel code |
lib |
Library code |
mm |
Memory management code |
net |
Kernel networking code |
samples |
Code examples and drivers that have not been fully developed |
scripts |
Various scripts used for the configuration and build process as well as standalone utility scripts |
security |
Kernel security support |
sound |
Sound and audio driver code |
usr |
Code used during kernel image creation |
virt |
Virtualization support code |
These directories will be referred to as needed in this document.
Configuration
The kernel uses a configuration system that specifies how every aspect of the kernel is built. This configuration information is generated based on selections by the user as well as dependency information
Refer to configuration section in the kernel building document. Show how to add / remove options in the config.
Adding Support for a new Carrier Board
Show how to add a carrier board in the 2.6.30 "emac-carrier" structure.
Driver Development
Basic info on driver structure here.
Licensing
Where to go for Additional Information
LDD3, mailing list, EMAC support.
