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x86 bootloader
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C 68.6%
Assembly 25.5%
Makefile 4.8%
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Hojun-Cho 98601ac381 add CPUID probe 
Just print vendor, Hypervisor...
2024-12-09 21:28:45 +09:00
biosboot can read character from keyboard now 2024-12-04 23:05:28 +09:00
boot add CPUID probe 2024-12-09 21:28:45 +09:00
installboot change btld_conf.h 2024-12-05 15:31:56 +09:00
installmbr change btld_conf.h 2024-12-05 15:31:56 +09:00
mbr can read character from keyboard now 2024-12-04 23:05:28 +09:00
.gitignore add va_list for print 2024-12-05 16:29:49 +09:00
btld_conf.h change btld_conf.h 2024-12-05 15:31:56 +09:00
btld_disk.h can read character from keyboard now 2024-12-04 23:05:28 +09:00
install.sh first commit 2024-11-27 17:06:47 +09:00
Makefile can read character from keyboard now 2024-12-04 23:05:28 +09:00
Makefile.inc can read character from keyboard now 2024-12-04 23:05:28 +09:00
README.md add readme 2024-11-27 22:56:59 +09:00
u.h add va_list for print 2024-12-05 16:29:49 +09:00

README.md

FAT16 bootloader

x86 FAT16 bootloader

How to run

1. install image to device
	install to device
		./install.sh /dev/sda
	create image and install
		./install.sh
2. run with qemu
	qemu-systme-i386 [device | ./build/img]

Disk layout

0x0000 ~ 0x0200: "mbr"
0x8000 ~ *     : Using FAT16 filesystem
0x8000 ~ 0x8200: "biosboot"
    exist "boot" somewhere in FAT16

How to work

mbr
	1. bios take us to 0x7C00
	2. relocate 0x7c00~0x7DFF to 0x7A00~0x7BFF
	3. load "biosboot" to 0x7C00~0x7DFF
	4. jump to 0x7c00 => biosboot
biosboot
	1. find "boot" file in FAT16 file sysytem
	2. load "boot" to 0x40000
	2-1. 0x40000 ~ 0x401ff: ELF information
		 0x40120 ~ *      : text, data, bss section 
	3. jump to 0x40120 => boot
boot
	1. set Global Descriptor Table
	2. enter protected mode
	2. set Interrupt Descriptor Table
	3. call boot function