Initial commit: SUB-OS 64-Bit Production Monolithic Operating System with LazyBox userland suite

arch/x86_64/boot/entry.asm

@@ -0,0 +1,37 @@
+[BITS 64]
+
+extern kernel_main
+extern __bss_start
+extern __bss_end
+extern stack_top
+
+global kernel_entry
+
+section .text
+kernel_entry:
+    ; 1. Set up high-performance dedicated 64 KB kernel stack
+    mov rsp, stack_top
+
+    ; 2. Preserve bootloader arguments safely in callee-saved registers R12 & R13
+    mov r12, rdi ; memory_map pointer
+    mov r13, rsi ; memory_map count
+
+    ; 3. Zero out the entire BSS section (.bss)
+    mov rdi, __bss_start
+    mov rcx, __bss_end
+    sub rcx, rdi
+    xor al, al
+    cld
+    rep stosb
+
+    ; 4. Restore bootloader arguments into RDI and RSI per AMD64 System V ABI
+    mov rdi, r12
+    mov rsi, r13
+
+    ; 5. Call kernel_main(memory_map, memory_map_count)
+    call kernel_main
+
+.hang:
+    cli
+    hlt
+    jmp .hang