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bztsrc--bootboot/x86_64-bios
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bzt 52c96a7d88 Initial commit
2018-06-05 20:34:03 +02:00
..
boot.asm Initial commit 2018-06-05 20:34:03 +02:00
bootboot.asm Initial commit 2018-06-05 20:34:03 +02:00
bootboot.inc Initial commit 2018-06-05 20:34:03 +02:00
fs.inc Initial commit 2018-06-05 20:34:03 +02:00
initrd.asm Initial commit 2018-06-05 20:34:03 +02:00
Makefile Initial commit 2018-06-05 20:34:03 +02:00
mkboot.c Initial commit 2018-06-05 20:34:03 +02:00
README.md Initial commit 2018-06-05 20:34:03 +02:00
tinf.inc Initial commit 2018-06-05 20:34:03 +02:00

README.md

BOOTBOOT BIOS / Multiboot Implementation

See BOOTBOOT Protocol for common details.

On BIOS based systems, the same image can be loaded via Multiboot, chainload from MBR or VBR (GPT hybrid booting) or run as a BIOS Expansion ROM (so not only the ramdisk can be in ROM, but the loader as well).

Machine state

IRQs masked. GDT unspecified, but valid, IDT unset. Code is running in supervisor mode in ring 0.

Installation

  1. BIOS disk: copy bootboot.bin to FS0:\BOOTBOOT\LOADER. You can place it inside your INITRD partition or outside of partition area as well (with dd conv=notrunc oseek=x). Finally install boot.bin in the master boot record (or in volume boot record if you have a boot manager), saving bootboot.bin's first sector's LBA number in a dword at 0x1B0. The mkboot utility will do that for you.

  2. BIOS ROM: install bootboot.bin in a BIOS Expansion ROM.

  3. GRUB: specify bootboot.bin as "kernel" in grub.cfg, or you can chainload boot.bin.

Limitations

  • As it boots in protected mode, it only maps the first 4G of RAM.
  • Compressed initrd in ROM is limited to ~96k.
  • The CMOS nvram does not store timezone, so always GMT+0 returned in bootboot.timezone.