Multitasking and Ring 3 groundwork

Added scheduler into irq0 #10 along with two example tasks to
demonstrate the task switching. Added a security level switch function
into syscalls #12. Added a kernel and user tss. Changed line endings to
Linux.

README.md

@@ -1,13 +1,15 @@
 minOS
 =====
 
-A simple hobby operating system based on a monolithic kernel design written purely in assembly language.
+A minimal bare bones operating system based on a monolithic kernel design written purely in Assembly language.
 
 Legacy boots from a pre-built disk image with planned support for GRUB multiboot.
 
+Kernel size: 8 KiB
+
 System Requirements:
 
-* RAM: 2MB - (3MB for User Mode)
+* RAM: 3 MiB
 * CPU: x86-64
 
 Microprocessors tested on:

src/boot.ASM

@@ -16,10 +16,10 @@ jmp start
 nop
 
 ; File System Info, legacy BIOS parameter block (bpb)
-OEM:				db "MIN OS"
+OEM:					db "MIN OS"
 bpbBytesPerSector:		dw 512
 bpbSectorsPerTrack:		dw 18
-bpbHeadsPerCylinder:		dw 2
+bpbHeadsPerCylinder:	dw 2
 bsDriveNumber:			db 0
 bsVolumeLabel:			db "minOS    "
 
@@ -30,8 +30,8 @@ start:
 	; Set up stack and segment registers
 	; Stop interrupts
 	cli
-	xor ax, ax  
-	mov ds, ax 
+	xor ax, ax
+	mov ds, ax
 	mov es, ax
 	mov fs, ax
 	mov gs, ax

src/build.ASM

@@ -1,3 +1,2 @@
 format binary as 'img'
-file 'boot.BIN'
-file 'k_main/k_main.BIN'
+file 'boot.BIN'

src/inc/e820.inc

@@ -1,125 +1,125 @@
-; =========================================================
-; minos -- a hobby operating system written for x86-64
-; Copyright (C) 2010-2016
-;
-; Detect memory
-; =========================================================
-
-e820_buffer: times 32    	db 0
-e820_bufferLength        	equ $ - e820_buffer
-line				db crlf, 0
-ram_e820h_msg			db 'Memory Available Below 1MB (bytes): ', 0
-ram_88h_msg			db 'Memory Available Above 1MB (kb): ', 0
-
-detect_memory:
-
-do_e820:
-	pusha
-
-	mov [total_mem], dword 0
-
-	mov di, e820_buffer
-	xor ebx, ebx
-	mov edx, 0534D4150h
-	mov ecx, e820_bufferLength
-	mov eax, 0E820h
-	int 15h
-	jc .nsupported
-
-.e820_check_1:
-	cmp eax, 0534D4150h
-	stc
-	jne .e820_check_4
-
-	push ebx
-	push ecx
-
-	mov eax, dword [di + 16]
-	cmp eax, 1
-	jg .not_os
-	mov eax, [di + 8]
-	add eax, [total_mem]
-	mov [total_mem], eax ; Save total mem
-	jmp .print_values
-
-.not_os:
-	cmp eax,2
-	jg .not_reserved
-	jmp .print_values
-
-.not_reserved:
-	cmp eax, 3
-	jg .not_reclaimed
-	jmp .print_values
-
-.not_reclaimed:
-	cmp eax, 4
-	jg .handle_acpinvs
-	jmp .print_values
-
-.handle_acpinvs:
-	cmp eax, 5
-	jg .print_values
-
-.print_values:
-	; TODO
-
-.e820_check_2:
-	pop ecx
-	cmp ecx, 24
-	jne .end_record
-	test dword [di + 20], 1
-	je .ignore
-	jmp .non_volatile
-
-.ignore:
-	; TODO
-
-.non_volatile:
-	test dword [di + 20], 1 shl 1
-	jne .end_record
-
-.end_record:
-	pop ebx
-	or ebx, ebx
-	je .e820_check_3
-
-	mov edx, 0534D4150h
-	mov ecx, e820_bufferLength
-	mov eax, 0E820h
-	int 15h
-
-	jnc .e820_check_1
-
-.e820_check_3:
-	clc
-
-.e820_check_4:
-	jmp .finish_e820
-
-.nsupported:
-	mov [mem_check], 0
-	mov al, 'n'
-	mov ah, 0eh
-	int 10h
-
-.finish_e820:
-	popa
-	call do_e88h
-	ret
-
-do_e88h:
-	push ax
-	mov ah, 88h
-	int 15h
-	jc .nsupported_88
-	mov [user_mem], ax
-	pop ax
-	ret
-
-	.nsupported_88:
-		mov [mem_check], 0
-    		mov al, 'n'
-    		mov ah, 0eh
-    		int 10h
-    		ret
+; =========================================================
+; minos -- a hobby operating system written for x86-64
+; Copyright (C) 2010-2016
+;
+; Detect memory
+; =========================================================
+
+e820_buffer: 	times 32    	db 0
+e820_bufferLength        		equ $ - e820_buffer
+line							db crlf, 0
+ram_e820h_msg					db 'Memory Available Below 1MB (bytes): ', 0
+ram_88h_msg						db 'Memory Available Above 1MB (kb): ', 0
+
+detect_memory:
+
+do_e820:
+	pusha
+
+	mov [total_mem], dword 0
+
+	mov di, e820_buffer
+	xor ebx, ebx
+	mov edx, 0534D4150h
+	mov ecx, e820_bufferLength
+	mov eax, 0E820h
+	int 15h
+	jc .nsupported
+
+.e820_check_1:
+	cmp eax, 0534D4150h
+	stc
+	jne .e820_check_4
+
+	push ebx
+	push ecx
+
+	mov eax, dword [di + 16]
+	cmp eax, 1
+	jg .not_os
+	mov eax, [di + 8]
+	add eax, [total_mem]
+	mov [total_mem], eax ; Save total mem
+	jmp .print_values
+
+.not_os:
+	cmp eax,2
+	jg .not_reserved
+	jmp .print_values
+
+.not_reserved:
+	cmp eax, 3
+	jg .not_reclaimed
+	jmp .print_values
+
+.not_reclaimed:
+	cmp eax, 4
+	jg .handle_acpinvs
+	jmp .print_values
+
+.handle_acpinvs:
+	cmp eax, 5
+	jg .print_values
+
+.print_values:
+	; TODO
+
+.e820_check_2:
+	pop ecx
+	cmp ecx, 24
+	jne .end_record
+	test dword [di + 20], 1
+	je .ignore
+	jmp .non_volatile
+
+.ignore:
+	; TODO
+
+.non_volatile:
+	test dword [di + 20], 1 shl 1
+	jne .end_record
+
+.end_record:
+	pop ebx
+	or ebx, ebx
+	je .e820_check_3
+
+	mov edx, 0534D4150h
+	mov ecx, e820_bufferLength
+	mov eax, 0E820h
+	int 15h
+
+	jnc .e820_check_1
+
+.e820_check_3:
+	clc
+
+.e820_check_4:
+	jmp .finish_e820
+
+.nsupported:
+	mov [mem_check], 0
+	mov al, 'n'
+	mov ah, 0eh
+	int 10h
+
+.finish_e820:
+	popa
+	call do_e88h
+	ret
+
+do_e88h:
+	push ax
+	mov ah, 88h
+	int 15h
+	jc .nsupported_88
+	mov [user_mem], ax
+	pop ax
+	ret
+
+	.nsupported_88:
+		mov [mem_check], 0
+		mov al, 'n'
+		mov ah, 0eh
+		int 10h
+		ret