In T10257#156493, @epriestley wrote:

Broadly:

• You only need to run arc liberate when developing Phabricator itself (e.g., writing Phabricator extensions or otherwise modifying Phabricator).
• The one ARM system (the Raspberry Pi) we have other direct evidence of users attempting to do installs on is explicitly not supported as a Phabricator host platform -- see Installation Guide. You can try, but you're on your own.
• If you're using an ARM system that could, in theory, broadly qualify as a "normal computer" to host and/or develop Phabricator this is something we might eventually look at supporting, but we don't currently have any evidence that anyone else is trying to do this. We are vanishingly unlikely to dedicate resources to ARM support for the benefit of only one user (if you are developing on ARM hardware) or one install (if you are hosting on ARM hardware).
• If you did read the "Installation Guide" and believed ARM hardware to reasonably qualify as "a normal computer", we can add additional language to make it clear that ARM is not included in what we consider "a normal computer".