feat(steps-guix): build linux64 kernel and switch via jump with backup

steps-guix/jump/linux64.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+#
+# SPDX-FileCopyrightText: 2026 Luo Yanpan
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+set -e
+
+new_kernel="/boot/vmlinuz-linux64"
+current_kernel="/boot/vmlinuz"
+backup_kernel="/boot/vmlinuz-32bit.backup"
+
+if [ ! -f "${new_kernel}" ]; then
+    echo "Missing new kernel image: ${new_kernel}" >&2
+    exit 1
+fi
+
+if [ -f "${current_kernel}" ]; then
+    cp -af "${current_kernel}" "${backup_kernel}"
+fi
+cp -af "${new_kernel}" "${current_kernel}"
+sync
+
+mkdir -p /etc
+if [ "${BARE_METAL}" = True ]; then
+    kexec -l "${current_kernel}" \
+        --append="root=/dev/sda1 rootfstype=ext3 init=/init rw rootwait"
+else
+    kexec -l "${current_kernel}" --console-serial \
+        --append="console=ttyS0 root=/dev/sda1 rootfstype=ext3 init=/init rw rootwait"
+fi
+kexec -e