Ubuntu Wiki

Packages-arch-specific is a database listing on which arches some packages should not be built.

Upstream maintenance is done in Debian; see: https://lists.ubuntu.com/archives/ubuntu-devel/2008-December/027076.html

And the Ubuntu branch is lp:~ubuntu-core-dev/packages-arch-specific/ubuntu and can be pushed to by core-devs. Do file an upstream bug before applying your changes!

It's preferable to merge the changes from upstream which is regularly imported via lp:packages-arch-specific.

After architectures have been added in the Ubuntu branch, wait until the next 2pm London time and upload your source package again to trigger a build on the new arches. If the new arches aren't picked up, ping buildd admins.