I am writing a simple 32-bit kernel. I'm booting with GRUB. Here is the code:
#include <stdio.h>
#include <sys/kernel.h>
#include <sys/tty.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <keys.h>
#include <sys/sata.h>
#include <string.h>
#include <sys/iob.h>
void *free_space;
void *kmalloc(size_t s) {
void *block = free_space;
free_space += s;
return block;
}
void meminit() {
/* Initialize the heap. It starts at 0xC0200000. */
free_space = (void *)0xC0200000;
}
char *buffer;
void read() {
buffer = malloc(512);
read_sata(0, 1, buffer);
}
void check() {
//outb(0x1F0, 0x00);
//printf("%d\n", inw(0x1F0));
}
void kernel_init(void) {
keys_init();
meminit();
}
void kernel_main(void) {
/* Initialize terminal interface */
terminal_initialize();
check();
abort();
}
linker script:
ENTRY(_start)
OUTPUT_FORMAT(elf32-i386)
SECTIONS {
/* The kernel will live at 3GB + 1MB in the virtual
address space, which will be mapped to 1MB in the
physical address space. */
. = 0xC0100000;
.text : AT(ADDR(.text) - 0xC0000000) {
*(.text)
*(.rodata*)
}
.data ALIGN (0x1000) : AT(ADDR(.data) - 0xC0000000) {
*(.data)
}
.bss : AT(ADDR(.bss) - 0xC0000000) {
_sbss = .;
*(COMMON)
*(.bss)
_ebss = .;
}
}
When i check if the multiboot header is valid, grub-file --is-x86-multiboot kernel.bin, it returns 1 (error). But when I comment the read() function, it's bootable. What is wrong here? Is it too large? The kernel is around 20KB.
