Linux Kernel Architecture

Mauerer runapp02.tex V2 - 09/04/2008 6:09pm Page 1166

Appendix B: Working with the Source Code

Git does not rank behind BitKeeper in terms of kernel developer productivity. Because it is a very useful

tool to track kernel development history, investigate errors, and carry out programming work, the focus

here is on its most important characteristics. However, if you are interested in detailed information on

the capabilities of git, refer to the documentation that comes with the product.

When working with git, it is very useful to create acloneof Linus Torvalds’s repository as it

contains the ‘‘official‘‘ kernel versions. The repository of developer version 2.6 is available at

git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git.Itcanbeclonedusing

the following command:

wolfgang@meitner>git clone git://git.kernel.org/pub/scm/linux/kernel/git-torvalds/linux-2.6.git

Depending on the network connection, a file transfer initiated by this command takes between a few

minutes and several hours (with extremely slow modems).

The following sections deal with several important commands used to track kernel development his-

tory, although these represent only part of the git functionality. Further information can be obtained by

invoking the online help withgit help. The help system provides an overview of available commands.

A detailed description of the individual commands can be requested by enteringgit helpcommand.

TrackingDevelopmentHistory

Git employscommitsto group development steps. When a new feature that requires modification of

severalfilesisaddedtothekernel,thechangestoallthefilesareconcentratedinacommitthatisapplied

as a whole to a repository. Each commit includes a comment to indicate the purpose of the change. An

individual comment may also be added to each file in a commit.

Displaying Commits

Thegit logcommand displays all commits applied to a repository. For example:

wolfgang@meitner>git log

commit f1d39b291e2263f5e2f2ec5d4061802f76d8ae67

tree 29c33d63b3679103459932d43b8818abdcc7d3d5

parent fd60ae404f104f12369e654af9cf03b1f1047661

author Unicorn Chang <[email protected]> Tue, 01 Aug 2006 12:18:07 +0800

committer Jeff Garzik <[email protected]> Thu, 03 Aug 2006 17:34:52 -0400

[PATCH] ahci: skip protocol test altogether in spurious interrupt code

Skip protocol test altogether in spurious interrupt code. If PIOS is receive

when it shouldn’t, ahci will raise protocol violation.

Signed-off-by: Unicorn Chang <[email protected]>

Signed-off-by: Jeff Garzik <[email protected]>

commit c54772e751c0262073e85a7aa87f093fc0dd44f1

tree 5b6ef64c20ac5c2027f73a59bc7a6b4b21f0b63e

parent e454358ace657af953b5b289f49cf733973f41e4

author Brice Goglin <[email protected]> Sun, 30 Jul 2006 00:14:15 -0400

committer Jeff Garzik <[email protected]> Thu, 03 Aug 2006 17:31:10 -0400

[PATCH] myri10ge - Fix spurious invokations of the watchdog reset handler