Phabricator is a FreeBSD-hosted service that provides pre-commit code review workflows. Revisions are created via a command-line tool (arc), reviewed and committed once accepted.

This page describes how to use the service hosted at

Admins can be contacted at


Before being able to create revisions for code review, you need to create an account and install the command-line client tools on your machine. This section details the process.

Create an Account

Visit Phabricator Registration to create your account.

If you have one, please use your FreeBSD username as email address so that the Phabricator admins can track who you are.

Install Command Line Client

Arcanist is the command-line client for Phabricator. It can be installed with packages (there are other version for php which may work better for you):

# pkg install arcanist-php74

... or from ports:

# cd /usr/ports/devel/arcanist ; make install

If you have archivers/arc installed (for example for ClamAV), then instead:

# pkg install arcanist-lib-php74

and then add to .cshrc (or .shrc):

# .cshrc
alias arc       /usr/local/lib/php/arcanist/bin/arc
# .shrc
alias arc="/usr/local/lib/php/arcanist/bin/arc"

Configure Client

Set up ~/.arcrc with the certificates required to access the online service. This process requires manually copy/pasting a cookie provided by the online service. Do this by typing the command below and following the online instructions:

$ arc install-certificate

After completion, configure Arcanist to use as the default URI:

$ arc set-config default

Create a Revision

Once you have finished preparing a change locally, you are ready to send it out for review.

Please make sure that your changeset does one thing (and one thing only) so that the review process goes smoothly. Small and self-contained changes are much easier to review!

Phabricator has two groups of participants in a review: Reviewers and Subscribers. Individuals and project groups may be Reviewers, and at least one reviewer must accept the revision for it to proceed. Subscribers are notified of the revision and any changes, but are not required to accept the revision. Subscribers may be individuals, project groups, and mailing lists.

Create a Revision via command line (if using SVN)

From the top of the SVN local copy, run the following command to create a new revision for the given paths:

$ arc diff --create [<path>] ...

This command will open your favorite editor with the following template to fill in:

<<Replace this line with your Revision Title>>


Test Plan:



# Describe the changes in this new revision.
# arc could not identify any existing revision in your working copy.
# If you intended to update an existing revision, use:
#   $ arc diff --update <revision>

Use these guidelines:

After saving and exiting your editor, the changeset will be created in Phabricator and Arcanist will print a tracking link for your revision:

If you specify paths diff you need to do this from $SRCBASE directory, otherwise command will fail with following diagnostic:

Usage Exception: There are no changes to generate a diff from!

Wrong way:

arc diff --create tools/fdt/

Right way

arc diff --create sys/tools/fdt/

Create a Revision via command line (if using git)

As for SVN, you must be at the top of your local repository clone. You also need to be on the branch where the changes you want to review are. The one difference is in the parameter of the arc diff --create command. Instead of <path>, use a commit range such as main (if you have made no updates to the main branch since you started working on your changes) or HEAD^, HEAD^^, etc., depending on how many commits you made in that branch (basically, it's the same argument you'd give to git diff to get the changes you want reviewed). Be sure to commit your changes locally using git commit first, then do:

$ arc diff --create [<range>]

Then proceed with filling in or completing the template displayed in your editor, as for the SVN case. You'll notice that the template will come prefilled with your git commit log message, so be sure to put in something meaningful there.

For git patch series, the scripts under may help. The process described in is also useful to create a live branch that the reviewers can pull from and test.

Create a Revision via Web Interface

Revisions can be created without having Arcanist (arc) installed by uploading a patch via the web interface. Patches can be created by diff, svn, git or other tools.

To make reviewing changes easier, always include as much context as possible with your diff. Phabricator will automatically reduce the context in the default display and when sending emails, but it allows the full context to be displayed on demand in the web interface.

To create a full diff, use one of the following commands.

    git diff -U999999 other-branch > change.diff
    git show -U999999 <commit-hash> > change.diff
    svn diff --diff-cmd=diff -x -U999999 > change.diff

To upload a new patch:

  1. Go to

  2. Click Create Diff in the upper right hand corner.

  3. Upload the patch file (change.diff in the examples above) or copy and paste the text diff.

  4. Click Create Diff in the lower right hand corner.

  5. Leave the drop down on Create a new Revision... and click Continue.

  6. Enter a descriptive title and summary
  7. Add reviewers and mailing lists that you want to be included in the review. Mailing lists are added as subscribers:


  8. Click Save.

To submit an updated patch:

  1. Go to

  2. Click Create Diff.

  3. Paste or upload the updated diff.
  4. Select the review you want to update from the Attach To dropdown and click Continue.

  5. Click Save.

Address Revision Feedback

If the reviewer does not accept your change and asks you to modify stuff in your patch, edit the files in your local client accordingly.

While doing so, fill in replies to any line-specific comments that the reviewer may have left on the site. Don't worry: saving those replies does not cause them to be sent out yet. You must click the Submit button at the very bottom to cause these to be sent out.

After addressing all comments, reupload the patch. path should included all paths that are part of the review, even if their contents haven't changed as part of this update.

arc diff --update DXXX [<path>]

(if using SVN) or

arc diff --update DXXX [<range>]

(if using Git).

Note that this will trigger a notification to the reviewers mentioning that the patch has been updated.

Obtain Approval and Commit

Once the reviewers are happy with your change, they will accept your patch (which will be denoted by a green tick on the web site). At this point, you are free to submit the change to svn or git. Just use svn commit or git push as usual.

NOTE: You must add the "Differential Revision" in the commit message, it is not in the summary.

NOTE: Do not use arc commit because it will not allow you to edit the commit message, and will use a non-standard (for FreeBSD) format.

If you use git you can also now do "arc amend".

Close the Revision

NOTE: If you have added the "Differential Revision" reference correctly to the commit message, Phabricator closes the revision automatically

It is important that you close the revision once you are done with it so that it does not clutter your dashboard nor your reviewers'. Do this by scrolling down to the bottom of the revision page, select the Close option from the Action dropdown menu just above the Comment field, and click Submit. The Close option will not be visible unless the revision is in the Accepted state.

You can close a revision (in any state) from the command line with the following command:

arc close-revision DXXX

Reviewer Workflow

This workflow applies to people reviewing patches sent to them via Phabricator.

Open the Revision

Click on the link that appears in the notification email you received to open Phabricator.

Review Revision and Add Feedback

Review the commit message provided along the patch and the diff for all affected files.

If you want to leave line-specific comments, do so by clicking on the line number. This will open a little popup under the line, allowing you to type whichever comment you may like.

If you have change-wide comments, scroll down to the bottom of the page and type them in the provided box. Note that line-specific comments are vastly preferred over change-wide ones!

Once you are done with your review, don't forget to click on the Submit button at the end.

Optional: Apply the Revision Locally

If you wish to test the patch on your machine, you can use Arcanist to download and apply it. Simply do:

$ arc patch D32

Using Diffusion

Diffusion is the repository browser component of Phabricator. You can use it to add comments to and begin a review for existing code in the source tree. The use is similar to reviewing a proposed patch. For example, you want to make comments on a source file.

1. Go to Diffusion which you can find on the left side of your Phabricator main page.

2. Click on the repository where the file is located (doc, src, ports).

3. Use the list of recent commits to locate the commit and click on it (for example r12345). You can also use "Browse" to navigate to the file.

4. Once you are in the phabricator view where you see the graphical diffs, make your comments on the source lines, same as when doing reviews.

5. On the action combo box at the bottom, choose "Raise concern".

Future Plans

Short Term

Medium Term


CategoryHowTo CategoryServices

Phabricator (last edited 2021-10-24T06:43:47+0000 by GrahamPerrin)