Initial commit.

5 files changed, 216 insertions, 0 deletions

diff --git a/kernel/SConscript b/kernel/SConscript
new file mode 100644
index 0000000..87fcb1f
--- /dev/null
+++ b/kernel/SConscript
@@ -0,0 +1,30 @@
+Import('env')
+
+env = env.Clone(
+	CC = 'i386-elf-gcc',
+	CCFLAGS = '-Wall -W -nostdinc -fno-builtin -fno-hosted -ggdb -std=gnu99',
+	LINK = 'i386-elf-ld',
+	LINKFLAGS = '-nostdinc -nostdlib',
+)
+
+def kernel_bld_generator(source, target, env, for_signature):
+	link_script = None
+	for s in source:
+		if s.suffix == '.ld':
+			link_script = s
+			break
+	if not link_script:
+		Exit(1)
+	return '$LINK $LINKFLAGS -o %s -T %s %s ' % (target[0], link_script, ' '.join(str(s) for s in source if s != link_script))
+	
+kernel_bld = Builder(
+	generator = kernel_bld_generator,
+	suffix = '',
+	src_suffix = '.o',
+	src_builder = 'Object',
+	target_scanner = ProgramScanner
+)
+
+env.Append(BUILDERS = {'Kernel' : kernel_bld})
+
+kernel = env.Kernel('kernel', ['kernel.ld', 'entry.c', 'main.c'])
diff --git a/kernel/entry.c b/kernel/entry.c
new file mode 100644
index 0000000..d040cfb
--- /dev/null
+++ b/kernel/entry.c
@@ -0,0 +1,92 @@
+#include "types.h"
+
+extern void addr_phys;
+extern void addr_virt;
+extern void addr_virt_end;
+extern void addr_load_virt;
+extern void addr_load_virt_end;
+
+extern void entry_stack;
+
+extern uint32_t entry_pagedir[];
+extern uint32_t entry_pagetable_low[];
+extern uint32_t entry_pagetable_high[];
+
+extern void main();
+
+asm(
+	".globl entry\n"
+	"entry:\n"
+	"mov $entry_stack_top,%esp\n"
+	"push %eax\n"
+	"call entry_main\n"
+);
+
+void entry_serial_out(char* str);
+
+void entry_main(uint32_t mb_magic, void* mb_info) {
+	entry_serial_out("entry_main()\n");
+	if(mb_magic != 0x2badb002) {
+		entry_serial_out("Multiboot magic word is wrong!\n");
+		goto stop;
+	}
+	entry_serial_out("Multiboot ok\n");
+	
+	// TODO: Copy multiboot information.
+	
+	// Create initial page tables.
+	for(unsigned int i = 0; i < 1024; i++) {
+		// Clear page directory.
+		entry_pagedir[i] = 0;
+		
+		// Identity mapping of the current code.
+		entry_pagetable_low[i] = ((uint32_t)&addr_phys & 0xffc00000) | (i << 12) | 0x003;
+		
+		// Map kernelspace.
+		if((i << 12) < ((uint32_t)&addr_virt_end & 0x003ff000 )) {
+			entry_pagetable_high[i] = ((uint32_t)&addr_load_virt + (i << 12)) | 0x003;
+		} else {
+			entry_pagetable_high[i] = 0;
+		}
+	}
+	
+	entry_pagedir[(uint32_t)&addr_phys >> 22] = (uint32_t)&entry_pagetable_low | 0x003;
+	entry_pagedir[(uint32_t)&addr_virt >> 22] = (uint32_t)&entry_pagetable_high | 0x003;
+	
+	// Mapping stack to top without creating another page directory.
+	entry_pagetable_high[1023] = (uint32_t)&entry_stack | 0x003;
+	entry_pagedir[1023] = (uint32_t)&entry_pagetable_high | 0x003;
+	
+	// Enable paging.
+	asm volatile(
+		"mov %0, %%cr3\n"
+		"mov %%cr0, %0\n"
+		"or $0x80000000, %0\n"
+		"mov %0, %%cr0\n"
+		: : "r" (&entry_pagedir) : "%0"
+	);
+	
+	// TODO: Check that segments are loaded and mapped right.
+	
+	// Call main() in virtual memory.
+	main();
+	
+	stop:
+	entry_serial_out("Halting.\n");
+	asm volatile(
+		"cli\n"
+		"hlt\n"
+	);
+	while(1);
+}
+
+#define outb(port, value) asm volatile("out %b0,%w1" : : "a" (value), "d" (port));
+
+void entry_serial_out(char* str) {
+	while(*str) {
+		if(*str == '\n') {
+			outb(0x3f8, '\r');
+		}
+		outb(0x3f8, *str++);
+	}
+}
diff --git a/kernel/kernel.ld b/kernel/kernel.ld
new file mode 100644
index 0000000..2bcbcbc
--- /dev/null
+++ b/kernel/kernel.ld
@@ -0,0 +1,57 @@
+OUTPUT_FORMAT("elf32-i386")
+ENTRY(entry)
+
+addr_phys = 0x00100000;
+addr_virt = 0xc0000000;
+
+addr_virt_end = ADDR(.bss) + SIZEOF(.bss);
+
+addr_load_virt = LOADADDR(.text);
+addr_load_virt_end = LOADADDR(.bss) + SIZEOF(.bss);
+
+SECTIONS {
+	
+	.text_low addr_phys : {
+		LONG(0x1badb002);
+		LONG(0x00000003);
+		LONG(-0x1badb002 -0x00000003);
+		
+		kernel/entry.o(.text)
+		kernel/entry.o(.rodata*)
+		. = ALIGN(0x1000);
+	}
+	
+	.data_low : {
+		kernel/entry.o(.data)
+		. = ALIGN(0x1000);
+	}
+	
+	.bss_low : {
+		kernel/entry.o(.bss)
+		. = ALIGN(0x1000);
+		entry_pagedir = .; . += 0x1000;
+		entry_pagetable_low = .; . += 0x1000;
+		entry_pagetable_high = .; . += 0x1000;
+		entry_stack = .; . += 0x1000; entry_stack_top = .;
+	}
+	
+	.text addr_virt : AT(LOADADDR(.bss_low) + SIZEOF(.bss_low)) {
+		magic_text = .; LONG(0x0f00ba02);
+		*(.text)
+		*(.rodata*)
+		. = ALIGN(0x1000);
+	}
+	
+	.data : AT(LOADADDR(.text) + SIZEOF(.text)) {
+		magic_data = .; LONG(0x0f00ba03);
+		*(.data)
+		*(.ctors)
+		. = ALIGN(0x1000);
+	}
+	
+	.bss : AT(LOADADDR(.data) + SIZEOF(.data)) {
+		*(.bss)
+		*(COMMON)
+		. = ALIGN(0x1000);
+	}
+}
diff --git a/kernel/main.c b/kernel/main.c
new file mode 100644
index 0000000..513894b
--- /dev/null
+++ b/kernel/main.c
@@ -0,0 +1,26 @@
+
+void kernel_serial_out(char* str);
+
+void main() {
+	
+	kernel_serial_out("main()\n");
+	
+	// TODO: GDT.
+	
+	asm volatile(
+		"cli\n"
+		"hlt\n"
+	);
+	while(1);
+}
+
+#define outb(port, value) asm volatile("out %b0,%w1" : : "a" (value), "d" (port));
+
+void kernel_serial_out(char* str) {
+	while(*str) {
+		if(*str == '\n') {
+			outb(0x3f8, '\r');
+		}
+		outb(0x3f8, *str++);
+	}
+}
diff --git a/kernel/types.h b/kernel/types.h
new file mode 100644
index 0000000..4fdca6b
--- /dev/null
+++ b/kernel/types.h
@@ -0,0 +1,11 @@
+#ifndef TYPES_H
+#define TYPES_H
+
+typedef signed char int8_t;
+typedef unsigned char uint8_t;
+typedef signed short int16_t;
+typedef unsigned short uint16_t;
+typedef signed int int32_t;
+typedef unsigned int uint32_t;
+
+#endif