@@ -1,1 +1,1 @@
-qemu-system-i386 -drive index=0,if=floppy,format=raw,file=./build/release/cedos.img -m 64 -monitor stdio -no-reboot -d int,cpu_reset,exec,in_asm -vnc :0 2> log/run_err.log+qemu-system-i386 -drive index=0,if=floppy,format=raw,file=./build/release/cedos.img -m 64 -monitor stdio -no-reboot -d int,cpu_reset,exec,in_asm -vnc :0 2> log/run_err.log

@@ -158,13 +158,13 @@ or $0x00000001, %eax
   mov %eax, %cr0
 
   # perform long jump to set code segment
-  ljmp $0x8, $protected
+  ljmp $0x18, $protected
 
 
 .code32
 protected:
   # setup registers with appropriate GDT values
-  mov $0x10, %eax
+  mov $0x20, %eax
   mov %eax, %ds
   mov %eax, %es
   mov %eax, %fs
@@ -186,7 +186,7 @@ or $0x80000010, %eax
   movl %eax, %cr0
 
   # jump to kernel code
-  ljmp $8, $0xC0000000
+  ljmp $0x18, $0xC0000000
 
   # loop until the heat death of the universe
 loop:
@@ -227,7 +227,7 @@ .byte 10
   .byte 0
 
 GDT_DESCRIPTOR:
-  .word 0x23
+  .word 0x39
   .int GDT
 
 IDT_DESCRIPTOR:

@@ -11,9 +11,15 @@ (uint8_t)(((limit >> 16) & 0x0F) | ((flags << 4) & 0xF0)), \
         (uint8_t)(base >> 24) \
     }
 
-GDT_ENTRY GDT[5] = {
+GDT_ENTRY GDT[7] = {
     // null descriptor
     GDT_MAKE_ENTRY(0x00000000, 0x00000000, 0x00, 0x0),
+
+    // 16 bit code descriptor
+    GDT_MAKE_ENTRY(0x00000000, 0x0000FFFF, 0x9A, 0x8),
+
+    // 16 bit data descriptor
+    GDT_MAKE_ENTRY(0x00000000, 0x0000FFFF, 0x92, 0x8),
 
     // identity mapping (code, ring 0)
     GDT_MAKE_ENTRY(0x00000000, 0x000FFFFF, 0x9A, 0xC),

@@ -38,6 +38,6 @@
 /*!
  * The GDT.
  */
-GDT_ENTRY GDT[5];
+GDT_ENTRY GDT[7];
 
 #endif

@@ -95,7 +95,7 @@ outb(PS2_WRTE_CONF, PS2_COMMAND);
     nop(); nop(); nop(); nop();
     outb(conf, PS2_DATA);
 
-    install_interrupt(PIC1_IRQ(0x01), keyboard_int_handler, 0x08, INT_GATE);
+    install_interrupt(PIC1_IRQ(0x01), keyboard_int_handler, 0x18, INT_GATE);
 
     pic_unmask_interrupt(0x01);
 

@@ -1,18 +1,13 @@
 .section .text.realmode
 .global realmode_int10h
+.code32
 realmode_int10h:
     push %ebp
     mov %esp, %ebp
+
+    cli
     
     pusha
-
-    push %ds
-    push %es
-    push %fs
-    push %ss
-
-    mov %cr3, %eax
-    push %eax
 
     mov %esp, %eax
     mov %eax, %esi
@@ -28,58 +23,116 @@
     push %esi
     push %edi
 
+    mov +16(%edi), %eax
+    push %eax
+    mov +12(%edi), %eax
+    push %eax
+    mov +8(%edi), %eax
+    push %eax
+
+    push %ebp
+    mov %esp, %ebp
+
     # disable paging
+    mov %cr3, %eax
+    push %eax
+
+    mov %cr0, %eax
+    and $0x3FFFFFFD, %eax
+    mov %eax, %cr0
+
     xor %eax, %eax
     mov %eax, %cr3
 
-    # switch to realmode temporarily
+    # switch to 16 bit protected mode
+    ljmp $0x8, $pmode16
+
+.code16
+pmode16:
+    # setup segments
+    movw $0x10, %ax
+    movw %ax, %ss
+    movw %ax, %ds
+    movw %ax, %es
+    movw %ax, %fs
+
+    # load real mode interrupt descriptor table
+    sidt (pmode_IDT)
+    lidt (realmode_IDT)
+
+    # switch to real mode
     mov %cr0, %eax
-    and $0x3FFFFFFC, %eax
+    and $0xFFFFFFFE, %eax
     mov %eax, %cr0
 
-    # perform long jump to set code segment
     ljmp $0, $realmode
-return_pmode:
+realmode:
+    # setup segments
+    movw $0x0000, %ax
+    movw %ax, %ss
+    movw %ax, %ds
+    movw %ax, %es
+    movw %ax, %fs
+
+    sti
+
+    # load arguments
+    movw +4(%bp), %ax
+    movw +8(%bp), %bx
+    movw +12(%bp), %cx
+
+    int $0x10
+
+    cli
+
+    lidt (pmode_IDT)
+
+    mov %cr0, %eax
+    or $0x00000001, %eax
+    mov %eax, %cr0
+
+    ljmp $0x18, $pmode32
+
+.code32
+pmode32:
     # set data segments
-    movw $0x10, %ax
+    movw $0x20, %ax
     movw %ax, %ss
     movw %ax, %ds
     movw %ax, %es
     movw %ax, %fs
 
-    # restore stack
+    # restore paging
+    pop %eax
+    mov %eax, %cr3
+
+    mov %cr0, %eax
+    or $0x80000010, %eax
+    mov %eax, %cr0
+
+    # clean up argument buffer
+    pop %ebp
+    add $12, %esp
+
+    # restore original stack
     pop %ebp
     pop %eax
     mov %eax, %esp
 
-    # restore original segments and registers
-    pop %eax
-    mov %eax, %cr3
-    
-    pop %ss
-    pop %fs
-    pop %es
-    pop %ds
+    popa
 
-    popa
+    sti
     
     # return
     pop %ebp
+    ret
 
 
-.code16
-realmode:
-    # setup real mode segments
-    movw $0x0000, %ax
-    movw %ax, %ss
-    movw %ax, %ds
-    movw %ax, %es
-    movw %ax, %fs
+realmode_IDT:
+  .word 0x3FF
+  .int 0
 
-    # perform the actual interrupt
+pmode_IDT:
+  .word 0
+  .int 0
 
-    mov %cr0, %eax
-    and $0x00000001, %eax
-    mov %eax, %cr0
-
-    ljmp $0x8, $return_pmode

@@ -65,17 +65,17 @@
 int interrupts_init(void) {
     for (uint32_t i = 0; i < INTERRUPT_COUNT; i++) {
         if (i == 0x03) {
-            install_interrupt(i, breakpoint_isr, 0x08, INT_GATE);
+            install_interrupt(i, breakpoint_isr, 0x18, INT_GATE);
         } else if (i == 0x08) {
-            install_interrupt(i, double_fault_isr, 0x08, INT_GATE);
+            install_interrupt(i, double_fault_isr, 0x18, INT_GATE);
         } else if (i == 0x0d) {
-            install_interrupt(i, gpf_isr, 0x08, INT_GATE);
+            install_interrupt(i, gpf_isr, 0x18, INT_GATE);
         } else if (i >= 0x21 || i < 0x28) {
-            install_interrupt(i, pic1_handler, 0x08, INT_GATE);
+            install_interrupt(i, pic1_handler, 0x18, INT_GATE);
         } else if (i >= 0x28 || i < 0x30) {
-            install_interrupt(i, pic2_handler, 0x08, INT_GATE);
+            install_interrupt(i, pic2_handler, 0x18, INT_GATE);
         } else {
-            install_interrupt(i, default_isr, 0x08, INT_GATE);
+            install_interrupt(i, default_isr, 0x18, INT_GATE);
         }
     }
     

@@ -26,7 +26,7 @@ #else
 #define PRINT_DBG(...) {}
 #endif
 
-extern void realmode_int10h(uint32_t mode);
+extern void realmode_int10h(uint32_t eax, uint32_t ebx, uint32_t ecx);
 
 int os_init(void) {
     core_init();
@@ -68,9 +68,11 @@ printk("Initializing root file system...");
     FAT_init();
     printk("done.");
 
-    printk("Testing realmode graphics switch...");
-    realmode_int10h(0x0D);
-    printk("done.\n");*/
+    while (1) {
+        graph[i++] = (i & 0x0F);
+
+        if (i > 320 * 240) { i = 0; }
+    }
 
 
     printk("Initialization finished.\n--------------\n");

@@ -209,5 +209,5 @@ // dump registers to stdout
 }
 
 int paging_init(void) {
-    install_interrupt(0x0e, page_fault_isr, 0x08, TRAP_GATE);
+    install_interrupt(0x0e, page_fault_isr, 0x18, TRAP_GATE);
 }

@@ -87,7 +87,7 @@ frame.esi = frame.edi = 0;
     frame.ebp = p->ebp;
     frame.esp = p->esp;
     frame.eflags = p->eflags;
-    frame.cs = 0x8;
+    frame.cs = 0x18;
 
     if (name == NULL) {
         frame.eip = entry_idle;
@@ -179,7 +179,7 @@ extern void* sched_interrupt;
 
 int sched_init(void) {
     // install scheduler interrupt
-    install_interrupt(PIC1_IRQ(0x00), &sched_interrupt, 0x08, INT_GATE);
+    install_interrupt(PIC1_IRQ(0x00), &sched_interrupt, 0x18, INT_GATE);
 
     current_pid = 0;
 

@@ -27,6 +27,6 @@ /*!
  * Installs the syscall interrupt to INT 0x30
  */
 int syscall_init(void) {
-    install_interrupt(0x30, &syscall_interrupt, 0x08, INT_GATE);
+    install_interrupt(0x30, &syscall_interrupt, 0x18, INT_GATE);
     return 1;
 }