The Boot Sequence and Kernel Entry
AOS++ utilizes a multi-stage bootloader known as AOS Bootloader to transition the system 16-bit Real Mode to 64-bit Long Mode.
This bootloader is also Multi-OS and supports PBFS file system.
This bootloader is made for UEFI and MBR, with future plans for PFI.
- Stage 1: Initial MBR/UEFI loading and drive number detection, as well as loading of Stage 2 and Stage 3
- Stage 2.1: Enabling of A20 Gate, loading of Gloabl Descriptor Table (GDT) and entering Protected Mode
- Stage 2.2: Setting up of initial 4-level paging structures (PML4) before jumping to Stage 3
- Stage 3.1: Initialization of drivers, PBFS as well as initial UI drawing sequence
- Stage 3.2: Loading of OS based of selection of the user from PBFS, and jumping to it