Add missing license headers
diff --git a/sw/boot_rom/bootstrap.h b/sw/boot_rom/bootstrap.h
index 03ea92f..e9434fb 100644
--- a/sw/boot_rom/bootstrap.h
+++ b/sw/boot_rom/bootstrap.h
@@ -1,3 +1,7 @@
+// Copyright lowRISC contributors.
+// Licensed under the Apache License, Version 2.0, see LICENSE for details.
+// SPDX-License-Identifier: Apache-2.0
+
#ifndef _F_BOOTSTRAP_H__
#define _F_BOOTSTRAP_H__
diff --git a/sw/boot_rom/crt0.S b/sw/boot_rom/crt0.S
index ac53f7f..35c6fc4 100644
--- a/sw/boot_rom/crt0.S
+++ b/sw/boot_rom/crt0.S
@@ -1,3 +1,7 @@
+// Copyright lowRISC contributors.
+// Licensed under the Apache License, Version 2.0, see LICENSE for details.
+// SPDX-License-Identifier: Apache-2.0
+
.section .text
exception_handler:
diff --git a/sw/boot_rom/rom_link.ld b/sw/boot_rom/rom_link.ld
index c8fd0b5..1719116 100644
--- a/sw/boot_rom/rom_link.ld
+++ b/sw/boot_rom/rom_link.ld
@@ -1,3 +1,7 @@
+/* Copyright lowRISC contributors. */
+/* Licensed under the Apache License, Version 2.0, see LICENSE for details. */
+/* SPDX-License-Identifier: Apache-2.0 */
+
OUTPUT_ARCH(riscv)
/* required to correctly link newlib */
diff --git a/sw/exts/common/_crt.c b/sw/exts/common/_crt.c
index e176867..66721b3 100644
--- a/sw/exts/common/_crt.c
+++ b/sw/exts/common/_crt.c
@@ -1,3 +1,7 @@
+// Copyright lowRISC contributors.
+// Licensed under the Apache License, Version 2.0, see LICENSE for details.
+// SPDX-License-Identifier: Apache-2.0
+
#include <string.h>
#include "common.h"
diff --git a/sw/exts/common/link.ld b/sw/exts/common/link.ld
index 93d7d61..803020a 100644
--- a/sw/exts/common/link.ld
+++ b/sw/exts/common/link.ld
@@ -1,3 +1,7 @@
+/* Copyright lowRISC contributors. */
+/* Licensed under the Apache License, Version 2.0, see LICENSE for details. */
+/* SPDX-License-Identifier: Apache-2.0 */
+
OUTPUT_ARCH(riscv)
/* required to correctly link newlib */
diff --git a/sw/lib/handler.h b/sw/lib/handler.h
index 6c99ef4..6af92d3 100644
--- a/sw/lib/handler.h
+++ b/sw/lib/handler.h
@@ -1,3 +1,7 @@
+// Copyright lowRISC contributors.
+// Licensed under the Apache License, Version 2.0, see LICENSE for details.
+// SPDX-License-Identifier: Apache-2.0
+
#ifndef _HANDLER_H_
#define _HANDLER_H_
diff --git a/sw/lib/rv_timer.h b/sw/lib/rv_timer.h
index 7d74c6e..0228d0a 100644
--- a/sw/lib/rv_timer.h
+++ b/sw/lib/rv_timer.h
@@ -1,3 +1,7 @@
+// Copyright lowRISC contributors.
+// Licensed under the Apache License, Version 2.0, see LICENSE for details.
+// SPDX-License-Identifier: Apache-2.0
+
#ifndef _F_LIB_RV_TIMER_H__
#define _F_LIB_RV_TIMER_H__
