Configure your environment¶
For this workshop we prepared a docker image with everything you need installed for you. If you prefer installing yourself, follow the normal tutorial since "Booting".
Install docker in your distro.
For Ubuntu or Debian based distros, use the following command:
sudo apt update
sudo apt install docker-ce
sudo service docker start
For Arch Linux based distros, use the following commands:
sudo pacman -S docker
sudo systemctl start docker.service
sudo systemctl enable docker.service
Now, lets launch docker and download the source code:
mkdir linux
sudo docker run -i -t --volume $(realpath linux):/linux -w /linux rocha1558/lkcamp-kerneltools:slim
docker# git clone --depth 1 -b staging-testing git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
Build and Run¶
Lets compile and run using virtme
docker# cd /linux/staging
docker# virtme-configkernel --defconfig
docker# make -j$(nproc)
docker# virtme-run --kdir=.
root@(none):/# uname -r
Make some change¶
Lets hack the kernel a bit:
To exit virtme, press ctrl+a x
docker# vim init/main.c
Search for the kernel_init() function and add the following line just after rcu_end_inkernel_boot();
pr_err("\n================\nHello LKCAMP !!!\n================\n\n");
Save and close the file and compile again:
docker# make -j$(nproc)
docker# virtme-run --kdir=.
You should see your print there :)
Send your first patch¶
Configure your mail¶
As it was already mentioned the kernel development is made through mail. So setup your git to send mails. Edit the following file:
docker# cd /linux/staging && vim .git/config
And add the lines:
[sendemail]
smtpEncryption = tls
smtpServer = smtp.gmail.com
smtpUser = your.email@gmail.com
smtpServerPort = 587
[user]
name = <your name>
email = <your email>
Testing git send-email¶
docker# echo -e "\nChecking if send-email works\n" >> README
docker# git add README && git commit -m "Testing git send-email"
docker# git send-email --suppress-cc=all --to=<your email> HEAD^
Check your mailing box
Beware with gmail secure
Gmail has a security feature that block e-mail send. To disable this feature access de URL above and turn off.
2FA Gmail
If you have 2FA enabled in your Gmail follow this tip:
If you have multifactor authentication setup on your gmail account, you will need to generate an app-specific password for use with git send-email. Visit https://security.google.com/settings/security/apppasswords to create it. Then you can add "smtpPass = Your password" in your .git/config
If you use other e-mail domain
Adapt your configuration.
Finding something to contribute¶
For the first contribution lets start easy and correct a simple thing as a typo inside the staging folder.
The staging folder contains temporary drivers that doesn't meet the kernel quality standards. Once those drivers are fixed, they are migrated to the drivers/ folder. So this is a great place to start, as there are several minor things to fix, and the community is used to receive patches from new contributors through the staging tree.
To find something to fix, there is a script called checkpatch that shows you several style errors in the file:
docker# cd /linux/staging
docker# scripts/checkpatch.pl -f drivers/staging/isdn/hysdn/hycapi.c
...
ERROR: that open brace { should be on the previous line
#312: FILE: drivers/staging/isdn/hysdn/hycapi.c:312:
+ if (chk == 1)
+ {
}}
...
Sending your first patch to the maintainer¶
Inside the kernel repo add your change to stage:
git add <the_file_you_changed>
Commit your changes:
git commit -s
To see how you should format your commit message, check how other commits were previously made in this same file.
To check this, you can go to:
https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git/log/<path to the file you changed>
Check how in this case, all commits starts with staging: android: vsoc:, so other changes to this file should also follow this model.
Also, you should mention which error from Checkpath you are fixing, check this example https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git/commit/?id=e4d7efbb91efc3040e3f1c645571c1769095ae79
From Beatriz Martins de Carvalho <martinsdecarvalhobeatriz@gmail.com>
Subject [PATCH v2] staging: rtl8723bs: hal: replace spaces by tabs.
Date Thu, 4 Apr 2019 10:09:30 -0300
Fix checkpatch error "ERROR: code indent should use tabs where possible"
in hal_com_phycfg.c:1726.
Signed-off-by: Beatriz Martins de Carvalho <martinsdecarvalhobeatriz@gmail.com>
---
Changes in v2:
- correction commit title
- added more information about the error
---
drivers/staging/rtl8723bs/hal/hal_com_phycfg.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/staging/rtl8723bs/hal/hal_com_phycfg.c b/drivers/staging/rtl8723bs/hal/hal_com_phycfg.c
index 828b328adab8..fc49cdfcd477 100644
--- a/drivers/staging/rtl8723bs/hal/hal_com_phycfg.c
+++ b/drivers/staging/rtl8723bs/hal/hal_com_phycfg.c
@@ -1723,7 +1723,7 @@ s8 phy_get_tx_pwr_lmt(struct adapter *adapter, u32 reg_pwr_tbl_sel,
idx_rate_sctn = get_rate_sctn_idx(data_rate);
if (band_type == BAND_ON_5G && idx_rate_sctn == 0)
- DBG_871X("Wrong rate 0x%x: No CCK in 5G Band\n", DataRate);
+ DBG_871X("Wrong rate 0x%x: No CCK in 5G Band\n", DataRate);
/* workaround for wrong index combination to obtain tx power limit, */
/* OFDM only exists in BW 20M */
--
2.17.1
Checkpatch your patch first and solve the errors:
perl scripts/checkpatch.pl -g HEAD
Search maintainer's email, in this case catch the mailing list e-mail:
git show | perl scripts/get_maintainer.pl --nokeywords \
--nogit \
--nogit-fallback \
--norolestats
Check how the patch would be sent:
git send-email --annotate --suppress-cc=all --cc='~lkcamp/patches@lists.sr.ht' --dry-run HEAD^
Don't forget to add the emails from the maintainers. Add also lkcamp
e-mail to the list (~lkcamp/patches@lists.sr.ht), so we can give feedbacks at
each others patches.
Now, send your first patch to the maintainer:
git send-email --annotate --suppress-cc=all --cc='~lkcamp/patches@lists.sr.ht' HEAD^
Sending a second version of a patch¶
Note
This section shows how to send a second version of a patch that has already review by the community. If you haven't sent your patch to the mail lists, follow the previous section.
Many times, the kernel community will give feedback to improve your patch. It is not uncommon patches that are not accepted at first version. In that cases, make the modifications required and send a second version -V2 of your patch.
Modifying your commit¶
Make the modifications required and add them to stage:
git add <the_file_you_changed>
Add the alterations to your first commit. If your commit is the last in the tree, it's possible to just amend the staged alterations into the last commit:
git commit --amend
Sending a V2¶
Make a V2 from your patch:
git format-patch HEAD~ -v2
The previous command will provide a
Send it to the emails lists and maintainers.
git send-email <your_patch>.patch --to "<lists>","<mantainers>","<lkcamp list>"