Changed back to lower half kernel, since im dump.

I dont see the benefit of higher half (and could not get multiboot info)

kernel/arch/i386/boot.s

@@ -6,109 +6,34 @@
 .set MB_CHECKSUM,	-(MB_MAGIC + MB_FLAGS)	#checksum of above, to prove we are multiboot
 
 # Multiboot header
-.section .multiboot.data, "aw"
+.section .multiboot
 	.align 4
 	.long MB_MAGIC
 	.long MB_FLAGS
 	.long MB_CHECKSUM
 
  # Create stack
-.section .bootstrap_stack, "aw", @nobits
+.section .bss
 	stack_bottom:
 	.skip 16384		# 16 KiB
 	stack_top:
 
-# Preallocate pages
+.section .text
-.section .bss, "aw", @nobits
-	.align 4096
-	boot_page_directory:
-		.skip 4096
-	boot_page_table1:
-		.skip 4096
-
-# Kernel entrypoint
-.section .multiboot.text, "a"
 .global _start
 .type _start, @function
 _start:
-	# Physical address of boot_page_table1
+	movl $stack_top, %esp
-	movl $(boot_page_table1 - 0xC0000000), %edi
 
-	# First address to map is 0
+	pushl %eax
-	movl $0, %esi
+	pushl %ebx
 
-	# Map 1023 pages, 1024th will be VGA memory
+	call _init
-	movl $1023, %ecx
 
-
-1:
-	# Only map the kernel
-	cmpl $_kernel_start, %esi
-	jl 2f
-	cmpl $(_kernel_end - 0xC0000000), %esi
-	jge 3f
-
-	# Map physical address as "present, writable"
-	# Note that this maps .text and .rodata as writable. Mind security and map them as non-writable.
-	movl %esi, %edx
-	orl $0x003, %edx
-	movl %edx, (%edi)
-
-2:
-	# Size of page is 4096 bytes
-	addl $4096, %esi
-	# Size of entry in boot_page_table1 is 4 bytes
-	addl $4, %edi
-	# Loop to next entry if we haven't finished
-	loop 1b
-
-3:
-	# Map VGA memory to 0xC03FF000 as "present, writable"
-	movl $(0x000B8000 | 0x003), boot_page_table1 - 0xC0000000 + 1023 * 4
-
-	# The page table is used at both page directory entry 0 (virtually from 0x0
-	# to 0x3FFFFF) (thus identity mapping the kernel) and page directory entry
-	# 768 (virtually from 0xC0000000 to 0xC03FFFFF) (thus mapping it in the
-	# higher half). The kernel is identity mapped because enabling paging does
-	# not change the next instruction, which continues to be physical. The CPU
-	# would instead page fault if there was no identity mapping.
-
-	# Map the page table to virtual addresses 0x00000000 and 0xC0000000
-	movl $(boot_page_table1 - 0xC0000000 + 0x003), boot_page_directory - 0xC0000000 + 0
-	movl $(boot_page_table1 - 0xC0000000 + 0x003), boot_page_directory - 0xC0000000 + 768 * 4
-
-	# Set cr3 to the address of the boot_page_directory
-	movl $(boot_page_directory - 0xC0000000), %ecx
-	movl %ecx, %cr3
-
-	# Enable paging and the write-protect bit
-	movl %cr0, %ecx
-	orl $0x80010000, %ecx
-	movl %ecx, %cr0
-
-	# Jump to higher half with an absolute jump
-	lea 4f, %ecx
-	jmp *%ecx
-
-.section .text
-
-4:
-	# Now paging is fully set up and enabled
-
-	# Unmap the identity mapping since it is not unnecessary
-	movl $0, boot_page_directory + 0
-
-	# Reload crc3 to force a TLB flush for the changes to take effect
-	movl %cr3, %ecx
-	movl %ecx, %cr3
-
-	# Setup stack
-	mov $stack_top, %esp
- 
-	# Call into C code
 	call kernel_main
- 
+
-	# Hang if kernel_main returns
 	cli
-1:	hlt
+1:
+	hlt
 	jmp 1b
+
+.size _start, . - _start

kernel/arch/i386/linker.ld

@@ -2,37 +2,24 @@ ENTRY(_start)
  
 SECTIONS
 {
-	. = 0x00100000;
+	. = 1M;
  
-	_kernel_start = .;
+	.text BLOCK(4K) : ALIGN(4K)
-	.multiboot.data : {
-		*(.multiboot.data)
-	}
-
-	.multiboot.text : {
-		*(.multiboot.text)
-	}
-
-	. += 0xC0000000;
-
-	.text ALIGN(4K) : AT(ADDR(.text) - 0xC0000000)
 	{
+		*(.multiboot)
 		*(.text)
 	}
-	.rodata ALIGN(4K) : AT(ADDR(.rodata) - 0xC0000000)
+	.rodata BLOCK(4K) : ALIGN(4K)
 	{
 		*(.rodata)
 	}
-	.data ALIGN(4K) : AT(ADDR(.data) - 0xC0000000)
+	.data BLOCK(4K) : ALIGN(4K)
 	{
 		*(.data)
 	}
-	.bss ALIGN(4K) : AT(ADDR(.bss) - 0xC0000000)
+	.bss BLOCK(4K) : ALIGN(4K)
 	{
 		*(COMMON)
 		*(.bss)
-		*(.bootstrap_stack)
 	}
-
-	_kernel_end = .;
 }

kernel/arch/i386/tty.cpp

@@ -7,7 +7,7 @@
 
 static constexpr size_t VGA_WIDTH = 80;
 static constexpr size_t VGA_HEIGHT = 25;
-static uint16_t* const VGA_MEMORY = (uint16_t*)0xC03FF000;
+static uint16_t* const VGA_MEMORY = (uint16_t*)0xB8000;
 
 static size_t terminal_row;
 static size_t terminal_col;

kernel/include/kernel/tty.h

@@ -3,11 +3,8 @@
 #include <stddef.h>
 #include <sys/cdefs.h>
 
-__BEGIN_DECLS
 
 void terminal_initialize();
 void terminal_putchar(char c);
 void terminal_write(const char* data, size_t size);
 void terminal_writestring(const char* data);
-
-__END_DECLS

kernel/kernel/kernel.cpp

@@ -1,21 +1,60 @@
+#include <kernel/GDT.h>
+#include <kernel/kmalloc.h>
+#include <kernel/panic.h>
 #include <kernel/tty.h>
 
 #include <stdio.h>
-#include <stdint.h>
+#include <string.h>
+#include <stdlib.h>
 
+#define DISABLE_INTERRUPTS() asm volatile("cli")
+#define ENABLE_INTERRUPTS() asm volatile("sti")
+
+// https://www.gnu.org/software/grub/manual/multiboot/multiboot.html#Boot-information-format
+struct multiboot_info_t
+{
+	uint32_t flags;
+	uint32_t mem_lower;
+	uint32_t mem_upper;
+	uint32_t boot_device;
+	uint32_t cmdline;
+	uint32_t mods_count;
+	uint32_t mods_addr;
+	uint32_t syms[4];
+	uint32_t mmap_length;
+	uint32_t mmap_addr;
+	uint32_t drives_length;
+	uint32_t drives_addr;
+	uint32_t config_table;
+	uint32_t boot_loader_name;
+	uint32_t apm_table;
+	uint32_t vbe_control_info;
+	uint32_t vbe_mode_info;
+	uint16_t vbe_mode;
+	uint16_t vbe_interface_seg;
+	uint16_t vbe_interface_off;
+	uint16_t vbe_interface_len;
+	uint8_t framebuffer[22];
+#if 1
+	uint8_t  color_info[6];
+#endif
+} __attribute__((packed));
 
 extern "C"
-void kernel_main()
+void kernel_main(multiboot_info_t* mbi, uint32_t magic)
 {
-	asm volatile("cli");
+	DISABLE_INTERRUPTS();
-
 
 	terminal_initialize();
 
+	if (magic != 0x2BADB002)
+		Kernel::panic("Invalid magic in multiboot");
+	if (mbi->flags & 0b00100000)
+	{
+		printf("mmap_length: %d\n", mbi->mmap_length);
+		printf("mmap_addr:   %p\n", mbi->mmap_addr);
+	}
+
 	printf("Hello from the kernel!\n");
 
-	printf("%p\n", kernel_main);
-
-	int a = 10;
-	printf("%p\n", &a);
 }