First steps reading multiboot info. Added GDT.

6 files changed, 129 insertions, 3 deletions

diff --git a/kernel/SConscript b/kernel/SConscript
index 87fcb1f..d9988ac 100644
--- a/kernel/SConscript
+++ b/kernel/SConscript
@@ -27,4 +27,4 @@ kernel_bld = Builder(
 
 env.Append(BUILDERS = {'Kernel' : kernel_bld})
 
-kernel = env.Kernel('kernel', ['kernel.ld', 'entry.c', 'main.c'])
+kernel = env.Kernel('kernel', ['kernel.ld', 'entry.c', 'main.c', 'gdt.c'])
diff --git a/kernel/entry.c b/kernel/entry.c
index d040cfb..4dd2ee1 100644
--- a/kernel/entry.c
+++ b/kernel/entry.c
@@ -1,4 +1,5 @@
 #include "types.h"
+#include "multiboot.h"
 
 extern void addr_phys;
 extern void addr_virt;
@@ -18,13 +19,15 @@ asm(
 	".globl entry\n"
 	"entry:\n"
 	"mov $entry_stack_top,%esp\n"
+	"push %ebx\n"
 	"push %eax\n"
 	"call entry_main\n"
 );
 
 void entry_serial_out(char* str);
+void entry_serial_out_hex(uint32_t x);
 
-void entry_main(uint32_t mb_magic, void* mb_info) {
+void entry_main(uint32_t mb_magic, multiboot_info* mb_info) {
 	entry_serial_out("entry_main()\n");
 	if(mb_magic != 0x2badb002) {
 		entry_serial_out("Multiboot magic word is wrong!\n");
@@ -34,6 +37,17 @@ void entry_main(uint32_t mb_magic, void* mb_info) {
 	
 	// TODO: Copy multiboot information.
 	
+	entry_serial_out("Flags: ");
+	entry_serial_out_hex(mb_info->flags);
+	
+	if(mb_info->flags & (1 << 2)) {
+		entry_serial_out(mb_info->cmdline);
+		entry_serial_out("\n");
+	} else {
+		entry_serial_out("No cmdline.\n");
+	}
+	
+	
 	// Create initial page tables.
 	for(unsigned int i = 0; i < 1024; i++) {
 		// Clear page directory.
@@ -90,3 +104,12 @@ void entry_serial_out(char* str) {
 		outb(0x3f8, *str++);
 	}
 }
+
+void entry_serial_out_hex(uint32_t x) {
+	char str[] = "00000000\n";
+	for(int i = 0; i < 8; i++) {
+		int z = (x >> (28 - i * 4)) & 0xf;
+		str[i] = z < 10 ? '0' + z : 'a' - 10 + z;
+	}
+	entry_serial_out(str);
+}
diff --git a/kernel/gdt.c b/kernel/gdt.c
new file mode 100644
index 0000000..7d23289
--- /dev/null
+++ b/kernel/gdt.c
@@ -0,0 +1,28 @@
+#include "gdt.h"
+
+gdt_entry gdt[] = {
+	gdt_entry_init(0, 0, 0),
+	gdt_entry_init(0, 0xfffff, 0xc09a), // Code segment.
+	gdt_entry_init(0, 0xfffff, 0xc092), // Data segment.
+	gdt_entry_init(0, 0xfffff, 0xc0fa), // User mode code segment.
+	gdt_entry_init(0, 0xfffff, 0xc0f2), // User mode data segment.
+};
+
+gdt_ptr gdtr = {
+	.base = gdt,
+	.limit = sizeof(gdt) - 1
+};
+
+void gdt_init() {
+	asm volatile(
+		"lgdt (%0)\n"
+		"mov %w1, %%ds\n"
+		"mov %w1, %%es\n"
+		"mov %w1, %%fs\n"
+		"mov %w1, %%gs\n"
+		"mov %w1, %%ss\n"
+		"ljmp $0x08, $.flush\n"
+		".flush:\n"
+		: : "r" (&gdtr), "r" (0x10)
+	);
+}
diff --git a/kernel/gdt.h b/kernel/gdt.h
new file mode 100644
index 0000000..e2c5b46
--- /dev/null
+++ b/kernel/gdt.h
@@ -0,0 +1,28 @@
+#ifndef GDT_H
+#define GDT_H
+
+#include "types.h"
+
+typedef struct {
+	uint16_t limit_low;
+	uint16_t base_low;
+	uint8_t base_mid;
+	uint16_t flags;
+	uint8_t base_high;
+} __attribute__((packed)) gdt_entry;
+
+typedef struct {
+	uint16_t limit;
+	gdt_entry* base;
+} __attribute__((packed)) gdt_ptr;
+
+#define gdt_entry_init(b, l, f) { \
+	.base_low = (b & 0xffff), \
+	.base_mid = (b >> 16 & 0xff), \
+	.base_high = (b >> 24 & 0xff), \
+	.limit_low = (l & 0xffff), \
+	.flags = (f | (l >> 8 & 0x0f00))}
+
+void gdt_init();
+
+#endif
diff --git a/kernel/main.c b/kernel/main.c
index 513894b..25ad1f1 100644
--- a/kernel/main.c
+++ b/kernel/main.c
@@ -1,3 +1,4 @@
+#include "gdt.h"
 
 void kernel_serial_out(char* str);
 
@@ -5,7 +6,10 @@ void main() {
 	
 	kernel_serial_out("main()\n");
 	
-	// TODO: GDT.
+	gdt_init();
+	kernel_serial_out("GDT set.\n");
+	
+	kernel_serial_out("Halting.\n");
 	
 	asm volatile(
 		"cli\n"
diff --git a/kernel/multiboot.h b/kernel/multiboot.h
new file mode 100644
index 0000000..5a9e348
--- /dev/null
+++ b/kernel/multiboot.h
@@ -0,0 +1,43 @@
+#ifndef MULTIBOOT_H
+#define MULTIBOOT_H
+
+#include "types.h"
+
+typedef struct {
+	uint32_t flags;
+	
+	uint32_t mem_lower;
+	uint32_t mem_upper;
+	
+	uint32_t boot_device;
+	
+	char* cmdline;
+	
+	uint32_t mods_count;
+	uint32_t mods_addr;
+	
+	union {
+		uint32_t foo[3];
+	} syms;
+	
+	uint32_t mmap_length;
+	uint32_t mmap_addr;
+	
+	uint32_t drives_length;
+	uint32_t drives_addr;
+	
+	uint32_t config_table;
+	
+	uint32_t boot_loader_name;
+	
+	uint32_t apm_table;
+	
+	uint32_t vbe_control_info;
+	uint32_t vbe_mode_info;
+	uint32_t vbe_mode;
+	uint32_t vbe_interface_seg;
+	uint32_t vbe_interface_off;
+	uint32_t vbe_interface_len;
+} multiboot_info;
+
+#endif