Welma's structural lines¶

First, let's have a look at the main concepts that shape how Welma is designed. These all work together and need consistency.

Software update: Welma's smallest software package that can be installed is a partition (typically a GPT partition).
Secure boot: integrating secure boot also means being able to update those partitions that are protected under secure boot.
Partition layout: this is typically something that Welma users need to customize, as they have different needs (size, granularity of partitions...). And the ability to customize this must be compliant with software update and secure boot.

Here is an illustration of Welma's default partition layout:

┌────────────┐ ┌───────────┐ ┌───────────┐
│ bootloader │ │ bootflags │ │ datastore │
└────────────┘ └───────────┘ └───────────┘
┌─ boot.vfat (A) ────┐ ┌─ boot.vfat (B) ────┐
│                    │ │                    │
│ ┌─ Kernel image ─┐ │ │ ┌─ Kernel image ─┐ │
│ │ Linux kernel   │ │ │ │ Linux kernel   │ │
│ │ initramfs      │ │ │ │ initramfs      │ │
│ │ ...            │ │ │ │ ...            │ │
│ └────────────────┘ │ │ └────────────────┘ │
└────────────────────┘ └────────────────────┘
┌─ sysro.ext4 (A) ─────┐ ┌─ sysro.ext4 (B) ─────┐
│                      │ │                      │
│                      │ │                      │
└──────────────────────┘ └──────────────────────┘
┌─ appro.ext4 (A) ──────┐ ┌─ appro.ext4 (B) ──────┐
│                       │ │                       │
│                       │ │                       │
└───────────────────────┘ └───────────────────────┘
┌─ sysrw.ext4 ─────────────────────────────────────────┐
│                                                      │
│                                                      │
└──────────────────────────────────────────────────────┘