forked from PoliEcho-holding-org/kern
Implemented simple Multiboot1 kernel
This commit is contained in:
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#include "multiboot.h"
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#define FLAGS (MBH_PAGE_ALIGN | MBH_GRAPH_INFO)
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__attribute__ ((section(".multiboot")))
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struct multiboot_header mbh = {
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.magic = HEAD_MAGIC,
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.flags = FLAGS,
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.checksum = -(HEAD_MAGIC + FLAGS),
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// We don't need the a.out format fields
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.mode_type = 0,
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.width = 1920,
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.height = 1080,
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.depth = 32,
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};
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+200
@@ -0,0 +1,200 @@
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#include "stdint.h"
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#include "multiboot.h"
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/* Constants */
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#define COLS 80
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#define ROWS 24
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#define ATTR 0x0f
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#define VID_MEM 0xb8000
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/* Variables */
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static int xpos;
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static int ypos;
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static uint8_t* video;
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/* Forward Declarations */
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void cls(void);
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void itoa(char* buf, int base, int d);
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void putc(int c);
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void printf(const char* fmt, ...);
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/* Entry Point */
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void kmain(void) {
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uint32_t magic, addr;
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__asm__ volatile ("movl %%eax, %0; movl %%ebx, %1" : "=m"(magic), "=m"(addr));
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struct multiboot_info* mbi;
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video = (uint8_t*)VID_MEM;
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// Clear Screen
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cls();
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// Didn't boot with Multiboot
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if (magic != BOOT_MAGIC) {
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printf("Invalid Magic Number: 0x%x\n", magic);
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while (1);
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}
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mbi = (struct multiboot_info*)addr;
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printf("flags: 0x%x\n", mbi->flags);
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if (mbi->flags & MBI_MEMORY) {
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printf("mem_lower: %ukB, mem_upper: %ukB\n",
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mbi->mem_lower, mbi->mem_upper);
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}
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if (mbi->flags & MBI_BOOT_DEV) {
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printf("boot_device: 0x%x\n", mbi->boot_device);
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}
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if (mbi->flags & MBI_CMDLINE) {
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printf("cmdline: %s\n", mbi->cmdline);
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}
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if (mbi->flags & MBI_MODS) {
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printf("mods_count: %d, mods_addr: 0x%x\n",
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mbi->mods_count, mbi->mods_addr);
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struct multiboot_module* mod =
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(struct multiboot_module*)mbi->mods_addr;
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for (size_t i = 0; i < mbi->mods_count; i++) {
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printf(" start 0x%x, end: 0x%x, cmdline: %s\n",
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mod->start, mod->end, mod->cmdline);
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mod++;
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}
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}
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if (mbi->flags & MBI_SYMBOLS &&
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mbi->flags & MBI_ELF_HEAD) {
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printf("Flag SYMBOLS and ELF HEADER are both set!\n");
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while (1);
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}
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if (mbi->flags & MBI_MEMMAP) {
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printf("mmap_addr: 0x%x, mmap_length: 0x%x\n",
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mbi->mmap_addr, mbi->mmap_length);
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struct multiboot_memmap* mmap =
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(struct multiboot_memmap*)mbi->mmap_addr;
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while ((uint32_t)mmap < mbi->mmap_addr + mbi->mmap_length) {
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printf( " size: 0x%x, base: 0x%08x, "
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"length: 0x%08x, type: 0x%x\n",
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mmap->size, mmap->base, mmap->len, mmap->type);
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mmap = (struct multiboot_memmap*)
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((uint32_t)mmap + mmap->size + (sizeof(mmap->size)));
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}
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}
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while (1);
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}
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void cls(void) {
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for (int i = 0; i < COLS * ROWS * 2; i++) video[i] = 0;
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xpos = 0;
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ypos = 0;
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}
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void itoa(char* buf, int base, int d) {
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char* p = buf;
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char* p1;
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char* p2;
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uint32_t ud = d;
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int divisor = 10;
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if (base == 'd' && d < 0) {
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*p++ = '-';
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buf++;
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ud = -d;
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} else if (base == 'x') divisor = 16;
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do {
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int remainder = ud % divisor;
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*p++ = (remainder < 10) ? remainder + '0' : remainder + 'a' - 10;
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} while (ud /= divisor);
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*p = 0;
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p1 = buf;
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p2 = p - 1;
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while (p1 < p2) {
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char tmp = *p1;
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*p1 = *p2;
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*p2 = tmp;
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p1++;
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p2--;
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}
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}
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/* Put the character C on the screen. */
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void putc(int c) {
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if (c == '\n' || c == '\r') {
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newline:
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xpos = 0;
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ypos++;
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if (ypos >= ROWS)
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ypos = 0;
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return;
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}
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video[(xpos + ypos * COLS) * 2] = c & 0xFF;
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video[(xpos + ypos * COLS) * 2 + 1] = ATTR;
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xpos++;
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if (xpos >= COLS)
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goto newline;
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}
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void printf(const char *format, ...) {
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char** arg = (char**)&format;
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int c;
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char buf[20];
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arg++;
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while ((c = *format++) != 0) {
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if (c != '%') {
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putc (c);
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continue;
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}
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char *p, *p2;
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int pad0 = 0, pad = 0;
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c = *format++;
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if (c == '0') {
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pad0 = 1;
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c = *format++;
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}
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if (c >= '0' && c <= '9') {
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pad = c - '0';
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c = *format++;
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}
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switch (c) {
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case 'd':
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case 'u':
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case 'x':
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itoa(buf, c, *((int *) arg++));
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p = buf;
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goto string;
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break;
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case 's':
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p = *arg++;
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if (! p) p = "(null)";
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string:
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for (p2 = p; *p2; p2++);
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for (; p2 < p + pad; p2++) putc (pad0 ? '0' : ' ');
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while (*p) putc (*p++);
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break;
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default:
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putc(*((int *) arg++));
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break;
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}
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}
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}
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@@ -0,0 +1,43 @@
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OUTPUT_FORMAT(elf32-i386)
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ENTRY(kmain)
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SECTIONS {
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. = 0x00100000;
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/* Multiboot Header */
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.multiboot ALIGN(4) : {
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*(.multiboot)
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}
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/* Kernel Code */
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.text ALIGN(4) : {
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*(.text)
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*(.text.*)
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}
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/* Read-Only Data */
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.rodata ALIGN(4) : {
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*(.rodata)
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*(.rodata.*)
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}
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/* Read/Write Data */
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.data ALIGN(4) : {
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*(.data)
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*(.data.*)
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}
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/* BSS Section */
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.bss ALIGN(4) : {
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*(COMMON)
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*(.bss)
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*(.bss.*)
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}
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/* Discarded Sections */
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/DISCARD/ : {
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*(.note)
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*(.note.*)
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*(.comment)
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}
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}
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@@ -0,0 +1,19 @@
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include defaults.mk
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SRCS = $(shell find $(SRC) -name '**.c')
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OBJS = $(patsubst $(SRC)/%.c, $(BIN)/%.o, $(SRCS))
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LINKER = $(SRC)/linker.ld
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OUT = $(BIN)/kernel.elf
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.PHONY: all clean
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all: $(OUT)
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$(OUT): $(OBJS)
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$(LD) $(LDFLAGS) -T $(LINKER) -o $@ $^
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$(BIN)/%.o: $(SRC)/%.c
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$(CC) $(CFLAGS) -c -o $@ $<
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clean:
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rm -fr $(BIN)
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@@ -0,0 +1,96 @@
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#ifndef _MULTIBOOT_H
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#define _MULTIBOOT_H
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#include "stdint.h"
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#define __packed __attribute__ ((packed))
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#define HEAD_MAGIC 0x1BADB002
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#define BOOT_MAGIC 0x2BADB002
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// Multiboot Header Flags
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enum {
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MBH_PAGE_ALIGN = (1<<0),
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MBH_MEMORY_INFO = (1<<1),
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MBH_GRAPH_INFO = (1<<2),
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MBH_ADDR_FIELDS = (1<<16),
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};
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struct multiboot_header {
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uint32_t magic;
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uint32_t flags;
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uint32_t checksum;
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uint32_t header_addr;
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uint32_t load_addr;
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uint32_t load_end_addr;
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uint32_t bss_end_addr;
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uint32_t entry_addr;
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uint32_t mode_type;
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uint32_t width;
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uint32_t height;
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uint32_t depth;
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} __packed;
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// Multiboot Info Flags
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enum {
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MBI_MEMORY = (1<<0),
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MBI_BOOT_DEV = (1<<1),
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MBI_CMDLINE = (1<<2),
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MBI_MODS = (1<<3),
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MBI_SYMBOLS = (1<<4),
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MBI_ELF_HEAD = (1<<5),
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MBI_MEMMAP = (1<<6),
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MBI_DRIVES = (1<<7),
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MBI_CONF_TAB = (1<<8),
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MBI_BOOTLD_NAME = (1<<9),
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MBI_APM_TABLE = (1<<10),
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MBI_VBE_TABLE = (1<<11),
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MBI_FB_TABLE = (1<<12),
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};
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struct multiboot_info {
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uint32_t flags;
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uint32_t mem_lower;
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uint32_t mem_upper;
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uint32_t boot_device;
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uint32_t cmdline;
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uint32_t mods_count;
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uint32_t mods_addr;
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uint32_t syms[4];
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uint32_t mmap_length;
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uint32_t mmap_addr;
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uint32_t drives_length;
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uint32_t drives_addr;
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uint32_t config_table;
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uint32_t bootloader_name;
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uint32_t apm_table;
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uint32_t vbe_control_info;
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uint32_t vbe_mode_info;
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uint32_t vbe_mode;
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uint32_t vbe_interface_seg;
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uint32_t vbe_interface_off;
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uint32_t vbe_interface_len;
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uint32_t framebuffer_addr;
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uint32_t framebuffer_pitch;
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uint32_t framebuffer_width;
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uint32_t framebuffer_height;
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uint32_t framebuffer_bpp;
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uint32_t framebuffer_type;
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uint32_t color_info;
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} __packed;
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struct multiboot_module {
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uint32_t start;
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uint32_t end;
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uint32_t cmdline;
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uint32_t __reserved;
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} __packed;
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struct multiboot_memmap {
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uint32_t size;
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uint64_t base;
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uint64_t len;
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uint32_t type;
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} __packed;
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#endif
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@@ -0,0 +1,23 @@
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#ifndef _STDINT_H
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#define _STDINT_H
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#define NULL ((void*)0)
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// Naitive width
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typedef unsigned int size_t;
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typedef signed int ssize_t;
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// Signed ints
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typedef signed char int8_t;
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typedef signed short int16_t;
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typedef signed int int32_t;
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typedef signed long long int64_t;
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// Unsigned ints
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typedef unsigned char uint8_t;
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typedef unsigned short uint16_t;
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typedef unsigned int uint32_t;
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typedef unsigned long long uint64_t;
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#endif
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