Remove alignment and assert maximum executable size

Only 480.5 KiB of memory are usable for the second stage in real mode. If the executable becomes larger than that, we override the Extended BIOS Data Area.

Author: phil-opp

bios/second_stage/second-stage-link.ld

@@ -6,20 +6,33 @@ SECTIONS {
     .start : {
         *(.start)
     }
-    .text : ALIGN(512) {
+    .text : {
         *(.text .text.*)
     }
-    .rodata : ALIGN(512) {
+    .rodata : {
         *(.rodata .rodata.*)
     }
-    .bss : ALIGN(512) {
+    .data : {
+        *(.data .data.*)
+    }
+    .bss : {
         *(.bss .bss.*)
     }
-    .data : ALIGN(512) {
-        *(.data .data.*)
+    .eh_frame : {
+        *(.eh_frame .eh_frame.*)
+    }
+    .eh_frame_hdr : {
+        *(.eh_frame_hdr .eh_frame_hdr.*)
     }
 
     . = ALIGN(512);
 
     _second_stage_end = .;
+
+    . = 0x0007FFFF - 2;
+    .end_marker :
+    {
+        SHORT(0xdead)       /* magic number for bootable disk */
+    }
+    . = 0x7c00 + 512;
 }