1. U-boot Source Code Clean
Up Project
and
How-to
Recruiting Volunteers!
Macpaul Lin
(2012/08/18)

2. Outline
• Why do we do clean up?
• Who should join the clean up project?
And How will you be benefited with it?
• How to do the clean up work?
• Summary.

3. Why do we do clean up?
• U-boot is old.
– It is an old boot loader project and widely be
used in various embedded systems.
– There are many dirty historical codes. Linux
has them, too.
• Coding style are mixed.
– It supports booting OS from various different
devices which leverage codes from various
open source projects. Such as dlmalloc, Linux,
and etc.

4. Why do we do clean up?
• Developers usually get confused.
– Some coding style really introduce problem
when doing debugging.
– New contributor usually get confused between
old and new coding style.
• This usually lead unnecessary time cost when
developers reviewing and fixing their patches.

5. Why do we do clean up?
• It follows Linux coding style.
• However, since u-boot has long history just
like Linux kernel, source codes some were
dirty and need to be clean up.
• New comers and new contributors usually
reference the old coding style. Hence the
patch is usually need to be reworked and
viewers spent lots of effort on replying mail.

6. Who should join the clean up project
and how will you be benefits with it?
• U-boot uses git and mailing list to
management the source code developing.
– Student who wants to be familiar with git
source version control.
– Student who wants to join a open source
project and practice with patch commitment
mailing discussion.
– People who is interested in boot loader with
embedded device development environments.

7. How to do the clean up work?
• U-boot project uses the checkpatch.pl in
Linux kernel to check the patches.
• Clean up patches must obey both Linux
coding style and u-boot coding style.
• Coding style
– http://www.denx.de/wiki/U-Boot/CodingStyle
• Patch rules
– http://www.denx.de/wiki/U-Boot/Patches

8. Steps to join u-boot project
1. Sign-up the mailing list
2. Clone the source code
3. Use checkpatch.pl to check the old
codes.
4. Fix warnings reported by checkpatch.pl
5. Use git send-email to commit the
cleanup back to mailing list.
6. Fix your patch if maintainer give you
suggestion to fix.

9. 1. Sign-up the mailing list
• Subscribe
http://lists.denx.de/mailman/listinfo/u-boot
Don't choose "yes"
because maintainers
will reply your patch by mail.

10. 2. Clone the source code
• Clone the source code
– git clone git://git.denx.de/u-boot.git u-boot.git
• Setting git users and email
– git config --global user.name "yourname";
– git config --global user.email "you@youremail";
• Make a working branch
– cd u-boot.git
– git branch cleanup
• Checkout the working branch and getting start
– git checkout cleanup

11. 3. Use checkpatch.pl to check
the old codes.
• Once you finish a patch, use
tools/checkpatch.pl to verify the patch is
clean before send it out.
• So we can use this checkpatch.pl to check
if the current files are clean.
• Most of the old code is inside “common
folder".

12. 3. Use checkpatch.pl to check
the old codes.
• 3.0 Export the path of checkpatch.pl into
$PATH
– export PATH=$PATH:~/u-boot.git/tools

13. 3. Use checkpatch.pl to check
the old codes.
• 3.1 find a unclean file in folder “common”
– For example: "bedbug.c"
– cd common
• 3.2 copy it as a backup
– cp bedbug.c bedbug.c.bak

14. 3. Use checkpatch.pl to check
the old codes.
• 3.3 remove “bedbug.c” as commit 'A'
because we will check the whole file later
– git rm bedbug.c
– git commit -s
• Input some reason because this is just a temporary
work.

15. 3. Use checkpatch.pl to check
the old codes.
• 3.4 now we recover the unclean file and
make this as a commit 'B'.
– mv bedbug.c.bak bedbug.c
– git add bedbug.c
– git commit -s
• Input the real commit log.

16. 4. Fix warnings reported by
checkpatch.pl
• 4.1 Create a folder for this commit 'B'
– mkdir patch
– cd patch
• 4.2 Export this commit 'B' (the latest
commit) and use checkpatch.pl to get the
report.
– git format-patch HEAD~1
– checkpatch 0001-cosmetic-add-bedbug.c-
back.patch

17. 4. Fix warnings reported by
checkpatch.pl
• 4.3 You will get the report from checkpatch.

18. 4. Fix warnings reported by
checkpatch.pl
• 4.4 Now you can fix all the error of
bedbug.c with your favorite editor based on
this report.
– cd .. (back to “common" folder)
– vim bedbug.c
– (you can also use “git diff” to check your
changes)

19. 4. Fix warnings reported by
checkpatch.pl
• 4.5 Create a clean commit "C" as the result
of your work.
– git add debug.c
– git commit -s

20. 4. Fix warnings reported by
checkpatch.pl
• 4.6 Now you have 3 commits “A,B,C” in
"cleanup" branch

21. 4. Fix warnings reported by
checkpatch.pl
• 4.7 We only need the last commit "C" to
send back to mailing list.
– Remove commit "B" in patch folder
• rm patch/0001-cosmetic-add-bedbug.c-back.patch
– Export the final patch commit "C"
• cd patch
• git format-patch HEAD~1
– Use checkpatch.pl to check it again.
• checkpatch 0001-cosmetic-clean-up-common-
bedbug.c-by-checkpatch.pl.patch

22. 5. Use git send-email to commit
the cleanup back to mailing list.
• 5.1 Finally send the patch out.
– git send-email 0001-cosmetic-clean-up-
common-bedbug.c-by-checkpatch.pl.patch
– Remember add maintainers to “To:” list to
review the patch.

23. 6. Fix your patch if maintainer
give you suggestion to fix.
• After a maintainer reviewed your patch, he
will reply your mail to inform you if the
patch has been accepted or the patch is
still need to be fixed.

24. Summary
• There are many old-style codes need to be
cleaned up. We need your help.
• Please join u-boot project.
– Just subscribe
http://lists.denx.de/mailman/listinfo/u-boot