tiny-floppy-bootloader

A fork of tiny-linux-bootloader that is floppy-bootable and still fits in the first sector. This bootloader expects to find the kernel immediately after it at sector 1.

For a more generally compatible fork of the original project, please see w98qi-tiny-floppy-bootloader

Differences and tips

• The boot sector is designed to fit within the first sector of a floppy disk. If you're booting from a floppy, it's assumed that the kernel is located directly after the bootloader in subsequent sectors.
• Separate initrd support has been commented out (you could add it back in) -- to get around this, compile your kernel with the initrd embedded using CONFIG_INITRAMFS_SOURCE
• By default build.sh and config.inc makes 1.44mb floppy images -- if you want to use 1.722mb or other sizes, you will have to edit config.inc and build.sh to accomodate

Features/Purpose

• No partition table needed
• Easy to convert to an obfuscated loader (think anti-forensics for crypted disks)
• Easy to modify for a custom experience
• Useful in embedded devices

Building

To build, you need to:

1. Edit build.sh and set paths to your kernel
2. Edit config.inc to set your kernel cmd line (keep it <15chars for the moment, disabling debug makes more room)
3. Run build.sh
   • Use build.sh --objdump to generate an objdump of bootloader.bin
4. Now you can dd this onto your disk, if you have a partition table already, then do not overwrite bytes 446-510 on the first sector (so use dd twice).

Your system should now boot with the new kernel.

Troubleshooting

You can use qemu to boot the image by running:

qemu-system-i386 -fda disk.img

and you can also connect the VM to gdb for actual debugging. There's an included gdb script to get you started.