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

steps-guix/linux-6.12.74/pass1.sh

@@ -0,0 +1,38 @@
+# SPDX-FileCopyrightText: 2026 Luo Yanpan
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+: "${KERNEL_SYSROOT:=/kernel-toolchain}"
+: "${KERNEL_TARGET:=x86_64-unknown-linux-musl}"
+
+kernel_env() {
+    export PATH="${KERNEL_SYSROOT}/bin:${PATH}"
+    export HOSTCFLAGS="-I${KERNEL_SYSROOT}/include"
+    export HOSTLDFLAGS="-L${KERNEL_SYSROOT}/lib"
+    export LD_LIBRARY_PATH="${KERNEL_SYSROOT}/lib:${LD_LIBRARY_PATH}"
+}
+
+kernel_make() {
+    kernel_env
+    make "${MAKEJOBS}" \
+        ARCH=x86_64 \
+        CROSS_COMPILE="${KERNEL_SYSROOT}/bin/${KERNEL_TARGET}-" \
+        "$@"
+}
+
+src_prepare() {
+    default
+}
+
+src_configure() {
+    kernel_make defconfig
+}
+
+src_compile() {
+    kernel_make
+}
+
+src_install() {
+    install -D -m 644 arch/x86/boot/bzImage \
+        "${DESTDIR}/boot/vmlinuz-linux64"
+}

steps-guix/linux-6.12.74/sources

@@ -0,0 +1 @@
+f https://linux-libre.fsfla.org/pub/linux-libre/releases/6.12.74-gnu/linux-libre-6.12.74-gnu.tar.xz d0071b065a7a5ba5ea9f638828beb113774f9f043182cbf2c6b205d403f074f5

steps-guix/manifest

@@ -9,3 +9,5 @@ build: argp-standalone-1.4.1
 build: musl-fts-1.2.7
 build: musl-obstack-1.2.3
 build: elfutils-0.194
+build: linux-6.12.74
+jump: linux64