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authorAlex Auvolat <alex.auvolat@ens.fr>2014-11-30 18:53:31 +0100
committerAlex Auvolat <alex.auvolat@ens.fr>2014-11-30 18:53:31 +0100
commitbee97e0b630976b96798246a3ef4eea8964099cf (patch)
tree797be16f6e2ac129c37fe6c7527444cc34658180 /kernel/l0
downloadmacroscope-bee97e0b630976b96798246a3ef4eea8964099cf.tar.gz
macroscope-bee97e0b630976b96798246a3ef4eea8964099cf.zip
Bare bones.
Diffstat (limited to 'kernel/l0')
-rw-r--r--kernel/l0/kmain.c126
-rw-r--r--kernel/l0/loader.s69
2 files changed, 195 insertions, 0 deletions
diff --git a/kernel/l0/kmain.c b/kernel/l0/kmain.c
new file mode 100644
index 0000000..9139856
--- /dev/null
+++ b/kernel/l0/kmain.c
@@ -0,0 +1,126 @@
+#if !defined(__cplusplus)
+#include <stdbool.h> /* C doesn't have booleans by default. */
+#endif
+#include <stddef.h>
+#include <stdint.h>
+
+/* Check if the compiler thinks if we are targeting the wrong operating system. */
+#if defined(__linux__)
+#error "You are not using a cross-compiler, you will most certainly run into trouble"
+#endif
+
+/* This tutorial will only work for the 32-bit ix86 targets. */
+#if !defined(__i386__)
+#error "This tutorial needs to be compiled with a ix86-elf compiler"
+#endif
+
+#include "multiboot.h"
+
+extern void k_highhalf_addr;
+
+/* Hardware text mode color constants. */
+enum vga_color
+{
+ COLOR_BLACK = 0,
+ COLOR_BLUE = 1,
+ COLOR_GREEN = 2,
+ COLOR_CYAN = 3,
+ COLOR_RED = 4,
+ COLOR_MAGENTA = 5,
+ COLOR_BROWN = 6,
+ COLOR_LIGHT_GREY = 7,
+ COLOR_DARK_GREY = 8,
+ COLOR_LIGHT_BLUE = 9,
+ COLOR_LIGHT_GREEN = 10,
+ COLOR_LIGHT_CYAN = 11,
+ COLOR_LIGHT_RED = 12,
+ COLOR_LIGHT_MAGENTA = 13,
+ COLOR_LIGHT_BROWN = 14,
+ COLOR_WHITE = 15,
+};
+
+uint8_t make_color(enum vga_color fg, enum vga_color bg)
+{
+ return fg | bg << 4;
+}
+
+uint16_t make_vgaentry(char c, uint8_t color)
+{
+ uint16_t c16 = c;
+ uint16_t color16 = color;
+ return c16 | color16 << 8;
+}
+
+size_t strlen(const char* str)
+{
+ size_t ret = 0;
+ while ( str[ret] != 0 )
+ ret++;
+ return ret;
+}
+
+static const size_t VGA_WIDTH = 80;
+static const size_t VGA_HEIGHT = 25;
+
+size_t terminal_row;
+size_t terminal_column;
+uint8_t terminal_color;
+uint16_t* terminal_buffer;
+
+void terminal_initialize()
+{
+ terminal_row = 0;
+ terminal_column = 0;
+ terminal_color = make_color(COLOR_LIGHT_GREY, COLOR_BLACK);
+ terminal_buffer = (uint16_t*) (&k_highhalf_addr + 0xB8000);
+ for ( size_t y = 0; y < VGA_HEIGHT; y++ )
+ {
+ for ( size_t x = 0; x < VGA_WIDTH; x++ )
+ {
+ const size_t index = y * VGA_WIDTH + x;
+ terminal_buffer[index] = make_vgaentry(' ', terminal_color);
+ }
+ }
+}
+
+void terminal_setcolor(uint8_t color)
+{
+ terminal_color = color;
+}
+
+void terminal_putentryat(char c, uint8_t color, size_t x, size_t y)
+{
+ const size_t index = y * VGA_WIDTH + x;
+ terminal_buffer[index] = make_vgaentry(c, color);
+}
+
+void terminal_putchar(char c)
+{
+ terminal_putentryat(c, terminal_color, terminal_column, terminal_row);
+ if ( ++terminal_column == VGA_WIDTH )
+ {
+ terminal_column = 0;
+ if ( ++terminal_row == VGA_HEIGHT )
+ {
+ terminal_row = 0;
+ }
+ }
+}
+
+void terminal_writestring(const char* data)
+{
+ size_t datalen = strlen(data);
+ for ( size_t i = 0; i < datalen; i++ )
+ terminal_putchar(data[i]);
+}
+
+#if defined(__cplusplus)
+extern "C" /* Use C linkage for kernel_main. */
+#endif
+void kmain(struct multiboot_info_t *mbd, int32_t mb_magic)
+{
+ terminal_initialize();
+ /* Since there is no support for newlines in terminal_putchar yet, \n will
+ produce some VGA specific character instead. This is normal. */
+ terminal_writestring("Hello, kernel World!\n");
+}
diff --git a/kernel/l0/loader.s b/kernel/l0/loader.s
new file mode 100644
index 0000000..a31fcf5
--- /dev/null
+++ b/kernel/l0/loader.s
@@ -0,0 +1,69 @@
+[EXTERN k_highhalf_addr]
+
+[GLOBAL loader] ; making entry point visible to linker
+
+[EXTERN kmain] ; kmain is defined in kmain.c
+
+; loader stack size
+LOADER_STACK_SIZE equ 0x8000 ; 8Kb
+
+; setting up the Multiboot header - see GRUB docs for details
+MODULEALIGN equ 1<<0 ; align loaded modules on page boundaries
+MEMINFO equ 1<<1 ; provide memory map
+FLAGS equ MODULEALIGN | MEMINFO ; this is the Multiboot 'flag' field
+MAGIC equ 0x1BADB002 ; 'magic number' lets bootloader find the header
+CHECKSUM equ -(MAGIC + FLAGS) ; checksum required
+
+section .text
+align 4
+MultiBootHeader:
+ dd MAGIC
+ dd FLAGS
+ dd CHECKSUM
+
+section .setup
+loader: ;here, we load our false GDT, used for having the kernel in higher half
+ lgdt [trickgdt]
+ mov cx, 0x10;
+ mov ds, cx;
+ mov es, cx;
+ mov fs, cx;
+ mov gs, cx;
+ mov ss, cx;
+
+ jmp 0x08:higherhalf
+
+section .text
+higherhalf: ; now we're running in higher half
+ mov esp, stack_top ; set up the stack
+
+ push eax ; pass Multiboot magic number
+ add ebx, k_highhalf_addr ; update the MB info structure so that it is in the new seg
+ push ebx ; pass Multiboot info structure
+
+ call kmain ; call kernel proper
+
+ cli ; disable interupts
+
+hang:
+ hlt ; halt machine should kernel return
+ jmp hang
+
+[section .setup] ; this is included in the .setup section, so that it thinks it is at 0x00100000
+
+trickgdt: ; our false GDT
+ dw gdt_end - gdt - 1 ; gdt limit
+ dd gdt ; gdt base
+
+gdt:
+ dd 0, 0 ; null GDT entry
+ db 0xFF, 0xFF, 0, 0, 0, 10011010b, 11001111b, 0x40 ; kernel code segment
+ db 0xFF, 0xFF, 0, 0, 0, 10010010b, 11001111b, 0x40 ; kernel data segment
+
+gdt_end:
+
+[section .bss]
+align 4
+stack_bottom:
+ resb LOADER_STACK_SIZE
+stack_top: