Documentation

documentation/2 - booting.md

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+# Boot into C
+
+> - [Mittos64 documentation chapter 2](https://github.com/thomasloven/mittos64/blob/master/doc/2_A_Bootable_Kernel.md).
+> - [Mittos64 documentation chapter 3](https://github.com/thomasloven/mittos64/blob/master/doc/3_Activate_Long_Mode.md)
+> - [Mittos64 documentation chapter 4](https://github.com/thomasloven/mittos64/blob/master/doc/4_Higher_Half_Kernel.md)
+
+`src/kernel/boot/boot.S` will set up the bootstrap processoc (BSP) for running higher-half c code in 64 bit mode as soon as possible.
+
+Data structures such as the Page Directory, GDT and Multiboot2 Headers are hardcoded as far as possible. The GDT is hardcoded in c, the rest in ASM.
+
+Mittos requires a MultiBoot2 compliant bootloader such as Grub 2.0 and assumes an x86_64 processor. Therefore several sanity checks are currently not performed.
+
+## Parsing multiboot data
+
+> - [Mittos64 documentation chapter 7](https://github.com/thomasloven/mittos64/blob/master/doc/7_Multiboot_Data.md)
+> - [The MultiBoot 2 specification](https://www.gnu.org/software/grub/manual/multiboot2/multiboot.html)
+
+`parse_multiboot2(struct taglist *tags)` in `src/kernel/boot/multiboot.c` goes through the taglist passed to the kernel from the bootloader and saves some relevant information into a global data structure.
+
+What's currently saved is:
+- Bootloader name (unused)
+- Kernel command line (unused)
+- Memory map
+- Framebuffer information
+- RSDP information
+
+## Exceptions and interrupts
+> - [Mittos64 documentation chapter 8](https://github.com/thomasloven/mittos64/blob/master/doc/8_Exceptions.md)
+
+## Relevant files:
+- `src/kernel/boot/boot.S`
+- `src/kernel/boot/boot_PT.S`
+- `src/kernel/boot/multiboot_header.S`
+- `src/kernel/cpu/gdt.c`
+- `src/kernel/boot/kmain.c`
+- `src/kernel/boot/multiboot.c`