Remove kernel code & long mode

bootloader/bios/defs.asm

@@ -1,4 +0,0 @@
-; sector = 512 bytes
-
-; first sector of stage 2, on disk.
-%assign PARAM_STAGE2_SECTOR 34

bootloader/bios/long_mode.asm

@@ -1,56 +0,0 @@
-SECTION .text
-USE32
-
-long_mode:
-.func: dq 0
-.page_table: dd 0
-
-.entry:
-    ; disable interrupts
-    cli
-
-    ; disable paging
-    mov eax, cr0
-    and eax, 0x7FFFFFFF
-    mov cr0, eax
-
-    ; enable FXSAVE/FXRSTOR, Page Global, Page Address Extension, and Page Size Extension
-    mov eax, cr4
-    or eax, 1 << 9 | 1 << 7 | 1 << 5 | 1 << 4
-    mov cr4, eax
-
-    ; load long mode GDT
-    lgdt [gdtr]
-
-    ; enable long mode
-    mov ecx, 0xC0000080               ; Read from the EFER MSR.
-    rdmsr
-    or eax, 1 << 11 | 1 << 8          ; Set the Long-Mode-Enable and NXE bit.
-    wrmsr
-
-    ; set page table
-    mov eax, [.page_table]
-    mov cr3, eax
-
-    ; enabling paging and protection simultaneously
-    mov eax, cr0
-    or eax, 1 << 31 | 1 << 16 | 1                ;Bit 31: Paging, Bit 16: write protect kernel, Bit 0: Protected Mode
-    mov cr0, eax
-
-    ; far jump to enable Long Mode and load CS with 64 bit segment
-    jmp gdt.lm64_code:.inner
-
-USE64
-
-.inner:
-    ; load all the other segments with 64 bit data segments
-    mov rax, gdt.lm64_data
-    mov ds, rax
-    mov es, rax
-    mov fs, rax
-    mov gs, rax
-    mov ss, rax
-
-    ; jump to specified function
-    mov rax, [.func]
-    jmp rax

bootloader/bios/main.asm

@@ -42,18 +42,13 @@ stage2:
     align 512, db 0
 stage2.end:
 
-; TODO: why? Stage 1 read limit?
-; Can we make this smaller?
 ; The maximum size of stage2 is 4 KiB,
-; This fill will throw an error if the subtraction
-; is negative.
+; This fill will throw an error if the subtraction is negative.
 times (4*1024)-($-stage2) db 0
 
-; LEGACY
-; Pad to 0x13000
-; This needs to match the value configured
-; in the stage3 linker script
-times (0x13000 - 0x7c00)-($-$$) db 0
+; Pad to 0x9000.
+; This needs to match the value configured in the stage3 linker script
+times (0x9000 - 0x7c00)-($-$$) db 0
 
 stage3:
     %defstr STAGE3_STR %[STAGE3]

bootloader/bios/stage2.asm

@@ -22,7 +22,6 @@ stage2.entry:
 
 %include "cpuid.asm"
 %include "gdt.asm"
-%include "long_mode.asm"
 %include "protected_mode.asm"
 %include "thunk.asm"
 
@@ -44,98 +43,12 @@ stage3.entry:
     xor eax, eax
     mov al, [disk]
     push eax
-    mov eax, kernel.entry
+    mov eax, 0x00
     push eax
     mov eax, [stage3 + 0x18]
     call eax
+    
 .halt:
     cli
     hlt
     jmp .halt
-
-kernel:
-.stack: dq 0
-.func: dq 0
-.args: dq 0
-
-.entry:
-    ; page_table: usize
-    mov eax, [esp + 4]
-    mov [long_mode.page_table], eax
-
-    ; stack: u64
-    mov eax, [esp + 8]
-    mov [.stack], eax
-    mov eax, [esp + 12]
-    mov [.stack + 4], eax
-
-    ; func: u64
-    mov eax, [esp + 16]
-    mov [.func], eax
-    mov eax, [esp + 20]
-    mov [.func + 4], eax
-
-    ; args: *const KernelArgs
-    mov eax, [esp + 24]
-    mov [.args], eax
-
-    ; long_mode: usize
-    mov eax, [esp + 28]
-    test eax, eax
-    jz .inner32
-
-    mov eax, .inner64
-    mov [long_mode.func], eax
-    jmp long_mode.entry
-
-.inner32:
-    ; disable paging
-    mov eax, cr0
-    and eax, 0x7FFFFFFF
-    mov cr0, eax
-
-    ;TODO: PAE (1 << 5)
-    ; enable FXSAVE/FXRSTOR, Page Global, and Page Size Extension
-    mov eax, cr4
-    or eax, 1 << 9 | 1 << 7 | 1 << 4
-    mov cr4, eax
-
-    ; set page table
-    mov eax, [long_mode.page_table]
-    mov cr3, eax
-
-    ; enabling paging and protection simultaneously
-    mov eax, cr0
-    ; Bit 31: Paging, Bit 16: write protect kernel, Bit 0: Protected Mode
-    or eax, 1 << 31 | 1 << 16 | 1
-    mov cr0, eax
-    
-    ; enable FPU
-    ;TODO: move to Rust
-    mov eax, cr0
-    and al, 11110011b ; Clear task switched (3) and emulation (2)
-    or al, 00100010b ; Set numeric error (5) monitor co-processor (1)
-    mov cr0, eax
-    fninit
-
-    mov esp, [.stack]
-    mov eax, [.args]
-    push eax
-    mov eax, [.func]
-    call eax
-.halt32:
-    cli
-    hlt
-    jmp .halt32
-
-USE64
-
-.inner64:
-    mov rsp, [.stack]
-    mov rax, [.func]
-    mov rdi, [.args]
-    call rax
-.halt64:
-    cli
-    hlt
-    jmp .halt64

bootloader/bootloader/linkers/x86-unknown-none.ld

@@ -3,7 +3,7 @@ OUTPUT_FORMAT(elf32-i386)
 
 SECTIONS {
     /* The start address must match bootloader.asm */
-    . = 0x13000;
+    . = 0x9000;
 
     . += SIZEOF_HEADERS;
     . = ALIGN(4096);