libvirt: Submitting patches
Description: libvirt, virtualization, virtualization API

# Submitting patches

The simplest way to send patches is to use the git-publish tool. All libvirt-related repositories contain a config file that tells git-publish to use the correct mailing list and subject prefix.

If you are a first-time contributor, you may wish to read some patch submission threads from the mailing list archive of the mailing list from the .gitpublish file.

Alternatively, you may send patches using git send-email.

The usual workflow of libvirt developer is:

    $ git checkout master
    $ git pull
    $ git checkout -t origin -b workbranch
    (hack, committing any changes along the way)

More hints on compiling can be found here. Make sure to express your agreement with the Developer Certificate of Origin by adding a "Signed-off-by" line to every commit message. When you want to post your patches:

    $ git pull --rebase
    (fix any conflicts)
    $ git send-email --cover-letter --no-chain-reply-to --annotate \
                     --confirm=always --to=devel@lists.libvirt.org master

For a single patch you can omit --cover-letter, but a series of two or more patches needs a cover letter.

Note that the git send-email subcommand may not be in the main git package and using it may require installation of a separate package, for example the "git-email" package in Fedora and Debian.

Avoid using mail clients for sending patches, as most of them will mangle the messages in some way, making them unusable for our purposes. Gmail and other Web-based mail clients are particularly bad at this.

If everything went well, your patch should show up on the devel list archives in a matter of minutes; if you still can't find it on there after an hour or so, you should double-check your setup. Note that, if you are not already a subscriber, your very first post to the mailing list will be subject to moderation, and it's not uncommon for that to take around a day.

Please follow this as close as you can, especially the rebase and git send-email part, as it makes life easier for other developers to review your patch set.

One should avoid sending patches as attachments, but rather send them in email body along with commit message. If a developer is sending another version of the patch (e.g. to address review comments), they are advised to note differences to previous versions after the --- line in the patch so that it helps reviewers but doesn't become part of git history. Moreover, such patch needs to be prefixed correctly with --subject-prefix=PATCHv2 appended to git send-email (substitute v2 with the correct version if needed though).

## Git Configuration

If this is your first time using git send-email, you will probably need to setup your global git configuration, to point to your outgoing SMTP server with something like:

    $ git config --global sendemail.smtpServer stmp.youremailprovider.net

If your email provider (often your employer) has configured a DMARC policy for their domain, there are some additional settings that will be required. Before doing this, check the DMARC policy with

    $ host -t txt _dmarc.$YOURDOMAIN.COM

If this returns no output, or contains p=none then no configuration is required. If it reports p=quarantine or p=reject, then the libvirt lists will apply DMARC countermeasures to your email. To ensure that git authorship is preserved add

    $ git config --global format.from "Your Name <your@email.com>"
    $ git config --global format.forceInBodyFrom true

This will force git to always add an additional line

    From: Your Name <your@email.com>

in the body of the patch, guaranteeing correct author records even when the main From header is rewritten by mailman.

If you get tired of typing --to=devel@lists.libvirt.org all the time, you can configure that to be automatically handled by adding a local repository setting:

    $ git config sendemail.to devel@lists.libvirt.org

This last setting is not required if using git-publish to send patches, as that auto-identifies the mailing list address from its config file stored in git.

## Review process

Reviewing patches may take a lot of effort with review bandwidth being limited in open source projects. Here are a few rules to follow to streamline the process:

> - don't contact individual maintainers/developers directly with your patches; reviewers are subscribed to the mailing list

> - do be patient; reviewers may be busy

> - do respond to reviewer's questions

> - don't ignore a suggestion from a reviewer; if you disagree discuss it on the list before sending a new version

> - do remind us of your patches on the list if they haven't gotten any attention for a prolonged period (>1 week) by replying to your patches with a "ping"

> - do test your patches before sending

Don't feel obliged to review whole patch series if you see any major problems in any of the comprising patches - just point them out on the list.