first commit

boot/Makefile

@@ -0,0 +1,17 @@
+include ../*.inc
+
+PROG=boot
+CSRCS= $(wildcard *.c)
+SSRCS= $(wildcard *.S)
+OBJS = $(SSRCS:.S=.o) $(CSRCS:.c=.o)
+
+CFLAGS+=-c -fno-pie
+CPPFLAGS+=-nostdinc -DLOADADDR=$(LOADADDR) -DLINKADDR=$(LINKADDR) -DBOOTMAGIC=$(BOOTMAGIC)
+LDFLAGS+= -s -T ld.script -Ttext=$(LINKADDR) --no-omagic
+
+${PROG}: $(OBJS)
+	@rm -f $(PROG)
+	$(LD) $(LDFLAGS) -o $(BDIR)/$(PROG) $(OBJS)
+
+clean:
+	rm -f $(PROG) $(PROG).bin $(OBJS)

boot/boot.c

@@ -0,0 +1,56 @@
+typedef int dev_t;
+
+#define SCREEN_WIDTH           80
+#define SCREEN_LENGTH          25
+#define VGA_BUFFER_ADDR         0xb8000
+
+char*
+memcpy(char *a, char *b, int l)
+{
+	for(int i = 0; i < l; ++i)
+		a[i] = b[i];
+	return a;
+}
+
+int
+strlen(char *s)
+{
+	int i = 0;
+	for(; s[i]; ++i)
+		;
+	return i;
+}
+
+char*
+itostr(int n, char *s)
+{
+	char buf[16];	
+	char *p = buf;
+
+	do {
+		*p++ = n%16;
+	}while((n/=16) != 0);
+
+	while(p > buf){
+		*s++ = "0123456789abcdef"[(int)*--p];
+	}
+	return s;
+}
+
+void
+boot(dev_t bootdev)
+{
+	char *p;
+    char s[SCREEN_WIDTH] = "booted on disk:0x";
+    short* vga = (short*)VGA_BUFFER_ADDR;
+
+	p = s+strlen(s);
+	p = itostr((int)bootdev, p);
+	for(int j = 0; j < SCREEN_LENGTH; ++j){
+		for (int i = 0; i < sizeof(s); ++i) {
+			vga[(j*SCREEN_WIDTH)  + (i + SCREEN_WIDTH*2)] = 0x9100 | s[i];
+		}
+	}
+	while(1)
+		;
+}

boot/gdt.S

@@ -0,0 +1,74 @@
+.file "gdt.S"
+
+/* memory segment types */
+#define	SDT_MEMRO	16	/* memory read only */
+#define	SDT_MEMROA	17	/* memory read only accessed */
+#define	SDT_MEMRW	18	/* memory read write */
+#define	SDT_MEMRWA	19	/* memory read write accessed */
+#define	SDT_MEMROD	20	/* memory read only expand dwn limit */
+#define	SDT_MEMRODA	21	/* memory read only expand dwn limit accessed */
+#define	SDT_MEMRWD	22	/* memory read write expand dwn limit */
+#define	SDT_MEMRWDA	23	/* memory read write expand dwn limit acessed */
+#define	SDT_MEME	24	/* memory execute only */
+#define	SDT_MEMEA	25	/* memory execute only accessed */
+#define	SDT_MEMER	26	/* memory execute read */
+#define	SDT_MEMERA	27	/* memory execute read accessed */
+#define	SDT_MEMEC	28	/* memory execute only conforming */
+#define	SDT_MEMEAC	29	/* memory execute only accessed conforming */
+#define	SDT_MEMERC	30	/* memory execute read conforming */
+#define	SDT_MEMERAC	31	/* memory execute read accessed conforming */
+
+#ifndef _ALIGN_TEXT
+# define _ALIGN_TEXT .align 2, 0x120
+#endif
+
+/* NB == No Binding: use .globl or .weak as necessary */
+#define _ENTRY_NB(x) \
+	.text; _ALIGN_TEXT; .type x,@function; x:
+#define _ENTRY(x)	.globl x; _ENTRY_NB(x)
+
+
+.text
+.code32
+
+	.align	8
+gdt:
+		/* 0x00 : null */
+	.space	8
+		/* 0x08 : flat code */
+	.word	0xFFFF			# lolimit
+	.word	0			# lobase
+	.byte	0			# midbase
+	.byte	SDT_MEMERAC | 0 | 0x80	# RXAC, dpl = 0, present
+	.byte	0xf | 0 | 0x40 | 0x80	# hilimit, xx, 32bit, 4k granularity
+	.byte	0			# hibase
+		/* 0x10 : flat data */
+	.word	0xFFFF			# lolimit
+	.word	0			# lobase
+	.byte	0			# midbase
+	.byte	SDT_MEMRWA | 0 | 0x80	# RWA, dpl = 0, present
+	.byte	0xf | 0 | 0x40 | 0x80	# hilimit, xx, 32bit, 4k granularity
+	.byte	0			# hibase
+		/* 0x18 : 16 bit code */
+	.word	0xFFFF			# lolimit
+	.word	(LINKADDR & 0xffff)	# lobase
+	.byte	(LINKADDR >> 16) & 0xff	# midbase
+	.byte	SDT_MEMERAC | 0 | 0x80	# RXAC, dpl = 0, present
+	.byte	0x0 | 0 | 0 | 0		# hilimit, xx, 16bit, byte granularity
+	.byte	(LINKADDR >> 20) & 0xff	# hibase
+		/* 0x20 : 16 bit data */
+	.word	0xFFFF			# lolimit
+	.word	(LINKADDR & 0xffff)	# lobase
+	.byte	(LINKADDR >> 16) & 0xff	# midbase
+	.byte	SDT_MEMRWA | 0 | 0x80	# RWA, dpl = 0, present
+	.byte	0x0 | 0 | 0 | 0		# hilimit, xx, 16bit, byte granularity
+	.byte	(LINKADDR >> 20) & 0xff	# hibase
+
+	
+.globl	Gdtr
+Gdtr:
+	.word	. - gdt -1
+	.long	gdt
+	.word	0
+
+.end

boot/ld.script

@@ -0,0 +1,26 @@
+OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
+OUTPUT_ARCH(i386)
+
+PHDRS
+{
+	text PT_LOAD;
+}
+SECTIONS
+{
+	.text : {
+		KEEP(srt0.o(.text))
+		*(.text)
+	} :text
+	etext = .;
+	.data : { *(.data) } :text
+	edata = .;
+	.bss : { *(.bss) } :text
+	ebss = .;
+    end = .;
+	/DISCARD/ : 
+    {
+        *(.note.gnu.property)
+        *(.comment)
+    }
+}
+ 

boot/srt0.S

@@ -0,0 +1,47 @@
+.file "srt0.S"
+
+#define BOOTSTACK 0xfffc
+#define	CR0_PE	0x00000001	/* Protected mode Enable */
+
+	.globl	end
+	.globl	edata
+	.globl	Gdtr
+	.globl	boot
+
+	.text
+	.code16
+	.align 16
+	.globl	_start
+_start:
+	popl	%eax
+	cmpl	$BOOTMAGIC, %eax
+	je	1f
+
+1:
+	popl	%edx
+	cli
+	pushl	%cs
+	popl	%ds
+	addr32	data32 lgdt	(Gdtr - LINKADDR)
+	movl	%cr0, %eax
+	orl	$CR0_PE, %eax
+	data32	movl %eax, %cr0
+	data32	ljmp $8, $1f
+
+1:
+	.code32
+	movl	$0x10, %eax
+	mov	%ax, %ds
+	mov	%ax, %ss
+	mov	%ax, %es
+	mov	%ax, %fs
+	mov	%ax, %gs
+	movl	$BOOTSTACK, %esp
+	pushl	%edx
+
+
+	// fill 0 .bss
+	xorl	%eax, %eax
+
+	call	boot;
+