include + update old linux targets/host.c

examples/arch/bochs/startup.s

@@ -13,20 +13,41 @@
 # checksum: -(magic+flags)
 .long -(0x1BADB002 + 0x3)
 
-
-
 # the initial kernel stack
 .section .kernel_stack
 .global os_stack
 .size os_stack, 4096
+
+# NOTE: New Start
+
+# .section .gdt
+# gdt_start:
+#     .quad 0x0000000000000000 # null descriptor
+#     .quad 0x00cf9a000000ffff # code segment descriptor: base=0, limit=4GB, 32-bit code
+#     .quad 0x00cf92000000ffff # data segment descriptor: base=0, limit=4GB, 32-bit data
+# gdt_end:
+#
+# gdt_descriptor:
+#     .word gdt_end - gdt_start - 1 # limit
+#     .long gdt_start # base
+#
+# .section .idt
+# idt_table:
+#     .space 256*8 # 256 entries x 8 bytes each
+# idt_descriptor:
+#     .word 256*8-1 # limit
+#     .long idt_table # base
+
+# NOTE: New End
+
 #.Lstack_bottom:
 os_stack:
-.byte 0
-#.skip 16384 # 16 KiB
-.skip 4094 # 4 KiB
-.byte 0
-.Lstack_top:
-
+    .byte 0
+    .skip 65565 # 64 KiB
+    # .skip 16384 # 16 KiB
+    # .skip 4094 # 4 KiB
+    .byte 0
+    .Lstack_top:
 
 
 # The linker script specifies _start as the entry point to the kernel and the
@@ -36,7 +57,9 @@ os_stack:
 .global _start
 .type _start, @function
 _start:
-	# Welcome to kernel mode! 
+# NOTE: Old Start
+
+	# Welcome to kernel mode!
 	# To set up a stack, we simply set the esp register to point to the top of
 	# our stack (as it grows downwards).
 	movl $.Lstack_top, %esp
@@ -54,6 +77,34 @@ _start:
 .Lhang:
 	jmp .Lhang
 
+# NOTE: Old End
+
+# NOTE: New Start
+
+#     cli
+#
+#     lgdt gdt_descriptor # GDT
+#     lidt idt_descriptor # IDT Stub
+#
+#     # set up segment registers (flat 32-bit)
+#     movw $0x10, %ax
+#     movw %ax, %ds
+#     movw %ax, %es
+#     movw %ax, %fs
+#     movw %ax, %gs
+#     movw %ax, %ss
+#     movl $.Lstack_top, %esp # set stack
+#
+#     # call main C function
+#     call os_main
+#
+#     cli
+#     hlt
+# .Lhang:
+#     jmp .Lhang
+
+# NOTE: New End
+
 # Set the size of the _start symbol to the current location '.' minus its start.
 # This is useful when debugging or when you implement call tracing.
 .size _start, . - _start