The original post: /r/ubuntu by /u/pourpasand on 2025-03-10 12:13:34.

I was curious about how Ubuntu serves APT packages, so I explored the archive.ubuntu.com repository. While browsing, I found something I didn’t quite understand. Specifically, in the directory: http://archive.ubuntu.com/ubuntu/dists/jammy/main/signed/ I saw filenames like: linux-5.4-amd64 linux-5.7-amd64 linux-amd64 linux-azure-amd64 linux-gcp-amd64 linux-kvm-amd64 linux-oem-5.4-amd64 linux-oem-5.6-amd64 linux-oem-amd64 linux-oem-osp1-amd64 linux-oracle-amd64 shim-amd64 shim-canonical-amd64

What exactly are these files? I understand that “amd64” refers to the architecture, but what’s the meaning of “gcp” here? Also, what is the purpose of the signed directory? Does it contain cryptographically signed kernel images, or something else?