CeDOS - Commit d8ed9423

boot: Move second stage back to 0x1000 This will allow the boot image to grow bigger in the future.
Celina Sophie Kalus
hello@celinakalus.de
Fri, 08 Dec 2023 20:31:49 +0100
4 files changed, 21 insertions(+), 13 deletions(-)
M boot/drives.s → boot/drives.s 
@@ -201,7 +201,7 @@ load_end:
   movw $0x0000, %si   # buffer address
   movw $0x1000, %ax
   movw %ax, %es
-  call print
+  ;call print
 
   movw $done_msg, %si
   call print
M boot/entry.s → boot/entry.s 
@@ -16,7 +16,7 @@ movw %ax, %es
   movw %ax, %fs
 
   # setup stack
-  movw $0x9000, %sp
+  movw $0x7c00, %sp
   movw %sp, %bp
 
   # save boot drive index

@@ -33,7 +33,7 @@ call print
 
   # load rest of bootloader
   movw $0x0000, %bx   # buffer address
-  movw $0x07e0, %ax
+  movw $0x0100, %ax
   movw %ax, %es       # buffer address (segment)
   movb $0x02, %ah     # function 0x02: read a sector
   movb $0x07, %al     # sectors to read count

@@ -44,7 +44,9 @@ lea bootdriv_id, %si
   movb (%si), %dl
 
   int $0x13
-  jnc bl_loaded
+  jc error
+
+  ljmp $0, $bl_loaded
 
   # auxiliary functions
 .global error

@@ -128,6 +130,7 @@ .ascii "Loading bootloader..."
   .byte 0
 
 .section .text
+.code16
 bl_loaded:
   mov $done_msg, %si
   call print
M boot/link.txt → boot/link.txt 
@@ -7,27 +7,32 @@ PART_TABLE_START = 0x00007DBE;
 
 MEMORY
 {
-  BOOT_VMA    :   ORIGIN = 0x00007C00, LENGTH = 0x00001000
+  STAGE1_VMA  :   ORIGIN = 0x00007C00, LENGTH = 0x00001000
+  STAGE2_VMA  :   ORIGIN = 0x00001000, LENGTH = 0x00001000
   BOOT_DATA   :   ORIGIN = 0x00009000, LENGTH = 0x00001000
   KERNEL_VMA  :   ORIGIN = 0xC0000000, LENGTH = 0x30000000
 }
 
 SECTIONS
 {
-  BOOT : AT(0x0000)
+  STAGE1 : AT(0x0000)
   {
     */*.o(.mbr)
     . = 510;
     BYTE(0x55)
     BYTE(0xAA)
-    */*.o(.text)
-  } >BOOT_VMA
+  } >STAGE1_VMA
 
-  .data : 
+  STAGE2 : AT(LOADADDR(STAGE1) + SIZEOF(STAGE1))
   {
+    */*.o(.text)
     */*.o(.rodata*)
     */*.o(.data)
-  } >BOOT_VMA
+  } >STAGE2_VMA
+
+  .data : AT(LOADADDR(STAGE2) + SIZEOF(STAGE2))
+  {
+  } >STAGE2_VMA
 
   .bss : 
   {
M boot/paging.c → boot/paging.c 
@@ -4,9 +4,9 @@ #include "string.h"
 
 
 void *create_kernel_environment() {
-    PAGE_DIR_ENTRY (*pdir)[PAGE_ENTRY_COUNT] = (void*)(1 * PAGE_SIZE);
-    PAGE_TABLE_ENTRY (*kernel)[PAGE_ENTRY_COUNT] = (void*)(2 * PAGE_SIZE);
-    PAGE_TABLE_ENTRY (*lowmem)[PAGE_ENTRY_COUNT] = (void*)(3 * PAGE_SIZE);
+    PAGE_DIR_ENTRY (*pdir)[PAGE_ENTRY_COUNT] = (void*)(2 * PAGE_SIZE);
+    PAGE_TABLE_ENTRY (*kernel)[PAGE_ENTRY_COUNT] = (void*)(3 * PAGE_SIZE);
+    PAGE_TABLE_ENTRY (*lowmem)[PAGE_ENTRY_COUNT] = (void*)(4 * PAGE_SIZE);
 
     // set everything to zero
     memset(pdir, 0, 3 * PAGE_SIZE);