From 51502e07d4f8005292f5f451ba1162e545350d2e Mon Sep 17 00:00:00 2001
From: Thomas Oltmann <thomas.oltmann.hhg@gmail.com>
Date: Tue, 8 Jul 2025 15:43:19 +0200
Subject: [PATCH] lboot now sets up an initial bootboot struct

---
 fernlader.ld |  4 +++-
 lboot.S      | 66 +++++++++++++++++++++++++++++++++++++++++++++++-----
 loader.c     | 12 ++++++++--
 3 files changed, 73 insertions(+), 9 deletions(-)

diff --git a/fernlader.ld b/fernlader.ld
index 0413c75..abcf9ac 100644
--- a/fernlader.ld
+++ b/fernlader.ld
@@ -1,3 +1,4 @@
+ENTRY(_start)
 PHDRS {
     all PT_LOAD;
 }
@@ -7,6 +8,7 @@ SECTIONS {
         *(.text, .rodata*)
         *(.data)
         *(.bss, COMMON)
+        . = ALIGN(4K);
+        lboot.o(.data.bootboot)
     } :all
-    memmap = ALIGN(8);
 }
diff --git a/lboot.S b/lboot.S
index 28bb358..870d664 100644
--- a/lboot.S
+++ b/lboot.S
@@ -165,7 +165,7 @@ _urunreal:  pop         %es
             ret
 
             // get_map: Retrieve memory map using e820 BIOS function
-get_map:    mov         $memmap, %di
+get_map:    mov         $bb_memmap, %edi
             xor         %ebx, %ebx
             mov         $0x534D4150, %edx // e820 magic number
 _gmnext:    movl        $0, 20(%di)
@@ -178,7 +178,8 @@ _gmnext:    movl        $0, 20(%di)
             add         $24, %di
             jmp         _gmnext
 _gmdone:    add         $24, %di
-            mov         %di, memmap_end
+            sub         $bootboot, %edi
+            mov         %edi, bb_size
             ret
 
             // paging: Set up initial page tables for long mode
@@ -236,9 +237,11 @@ _pgnext:    mov         %ecx, %eax
             ret
 
             // make_heap: find a memory range suitable for heap usage
-make_heap:  mov         $memmap-24, %si
+make_heap:  mov         $bb_memmap-24, %si
 _mhnext:    add         $24, %si
-            cmp         memmap_end, %si
+            mov         $bootboot, %eax
+            add         bb_size,   %eax
+            cmp         %ax, %si
             jae         _mhdone
 
             cmpl        $1, 16(%si)
@@ -508,7 +511,7 @@ pdp_ptr:    .long       0
 pml4_ptr:   .long       0
 
             // Points to the end of the memory map
-memmap_end: .word       0
+memmap_end: .short      0
 
 tx_buf:     .space      PACKET_SIZE
 
@@ -523,11 +526,62 @@ trampo64:
             mov         %eax, %gs
             mov         %eax, %ss
 
-            mov         initrd_ptr, %edi
+            // Mangle e820 memmap into bootboot's format
+            mov         $bb_memmap, %rsi
+            mov         $bb_memmap, %rdi
+            mov         $bootboot, %edx
+            add         bb_size,   %edx
+1:
+            mov          0(%rsi), %rax
+            mov          8(%rsi), %rcx
+            mov         16(%rsi), %ebx
+
+            cmp         $6, %ebx
+            jb          2f
+            mov         $2, %ebx
+2:          mov         type_table(%rbx), %bl
+
+            and         $-16, %rax
+            or          %rbx, %rax
+
+            mov         %rax, 0(%rdi)
+            mov         %rcx, 8(%rdi)
+            
+            add         $24, %rsi
+            add         $16, %rdi
+
+            cmp         %rdx, %rsi
+            jb          1b
+            sub         $bootboot, %edi
+            mov         %edi, bb_size
+
+            mov         $bootboot, %edi
             jmp         loader_main
 
+type_table: .byte       0
+            .byte       1
+            .byte       0
+            .byte       2
+            .byte       2
+            .byte       0
+
             // ToDo List:
             // - Sorting the memmap
             // - Sanitizing the memmap
             // - Translating the memmap to bootboot format
             // - Parsing a config file
+
+.section .data.bootboot
+bootboot:   .ascii      "BOOT"
+bb_size:    .long       128
+            .byte       1
+            .byte       0
+            .short      1
+            .short      0
+            .space      10, 0
+bb_ird_ptr: .quad       0
+bb_ird_size:.quad       0
+            .space      24, 0
+            .space      64, 0
+bb_memmap:
+            .space      4096-128, 0
diff --git a/loader.c b/loader.c
index 991b1d1..b482ccb 100644
--- a/loader.c
+++ b/loader.c
@@ -185,11 +185,19 @@ load_elf(file_t file, uintptr_t *entry)
 	return 0;
 }
 
+/*
+static void *
+alloc(size_t size, size_t align)
+{
+
+}
+*/
+
 void
-loader_main(void *initrd)
+loader_main(BOOTBOOT *bootboot_ptr)
 {
 	uint64_t entry = 0;
-	file_t elf = { initrd, MEG(2) };
+	file_t elf = { (void *)bootboot_ptr->initrd_ptr, MEG(2) };
 	if (load_elf(elf, &entry) < 0) {
 		panic("panic: Malformed ELF64 executable");
 	}