bootstrapping an OS

[orangecms]

When an OS kernel is loaded, it needs to know

• where it is loaded and its size; the load address is the initial PC and the size is known at build time
• the data that firmware passes; commonly EFI System Table or DTB from a register by convention
• the reserved memory regions, obtained from ACPI tables (via EFI tables) or DTB (/reserved-memory)

related: #29

To get the initial PC, store it in the first assembly instruction.
E.g., for RISC-V: auipc x3, 0 (add 0 to the PC)

[orangecms]

see also https://blogsystem5.substack.com/p/hardware-autoconfiguration
and https://docs.u-boot.org/en/latest/develop/devicetree/control.html