Update lib.rs

Author: litecreator

crates/dust_codegen/src/lib.rs

@@ -919,6 +919,9 @@ fn build_object_for_triple_with_config(
 
     let mut module = ObjectModule::new(builder);
     let ptr_ty = module.target_config().pointer_type();
+    let emit_kernel_handoff = emit_strings
+        .iter()
+        .any(|s| s == "xdv-boot: handoff to kernel.bin");
 
     // For bare-metal, we don't declare puts - kernel handles output differently
     let puts_func = if config.mode == BuildMode::BareMetal {
@@ -1028,6 +1031,9 @@ fn build_object_for_triple_with_config(
                     break;
                 }
             }
+            if emit_kernel_handoff {
+                emit_boot_kernel_handoff_call(&mut b, ptr_ty)?;
+            }
         }
 
         let zero = b.ins().iconst(cranelift_codegen::ir::types::I32, 0);
@@ -1047,6 +1053,33 @@ fn build_object_for_triple_with_config(
     Ok(obj.write().context("emit object")?)
 }
 
+/// In boot.bin mode, transfer control to preloaded kernel image.
+/// Reads entry offset from boot record (0x0600 + 44), adds kernel image base
+/// (0x00020000), and performs an indirect call.
+fn emit_boot_kernel_handoff_call(
+    b: &mut FunctionBuilder<'_>,
+    ptr_ty: cranelift_codegen::ir::Type,
+) -> Result<()> {
+    let bootrec_kernel_entry_ptr = b.ins().iconst(ptr_ty, i64::from(0x0600 + 44));
+    let kernel_entry_off_i32 = b.ins().load(
+        cranelift_codegen::ir::types::I32,
+        cranelift_codegen::ir::MemFlags::new(),
+        bootrec_kernel_entry_ptr,
+        0,
+    );
+    let kernel_entry_off_ptr = b.ins().uextend(ptr_ty, kernel_entry_off_i32);
+    let kernel_image_base = b.ins().iconst(ptr_ty, 0x0002_0000);
+    let kernel_entry_addr = b.ins().iadd(kernel_image_base, kernel_entry_off_ptr);
+
+    let mut kernel_sig = Signature::new(b.func.signature.call_conv);
+    kernel_sig
+        .returns
+        .push(AbiParam::new(cranelift_codegen::ir::types::I32));
+    let kernel_sig_ref = b.import_signature(kernel_sig);
+    b.ins().call_indirect(kernel_sig_ref, kernel_entry_addr, &[]);
+    Ok(())
+}
+
 /// Kernel sector window reserved by xdv-os boot stage (128 * 512 bytes).
 const KERNEL_MAX_BYTES: usize = 128 * 512;
 /// VGA text mode base physical address.