Hi Mike,
On 2025-07-27 11:37:33+0300, Mike Rapoport wrote:
From: "Mike Rapoport (Microsoft)" rppt@kernel.org
Testing kexec handover requires a kernel driver that will generate some data and preserve it with KHO on the first boot and then restore that data and verify it was preserved properly after kexec.
To facilitate such test, along with the kernel driver responsible for data generation, preservation and restoration add a script that runs a kernel in a VM with a minimal /init. The /init enables KHO, loads a kernel image for kexec and runs kexec reboot. After the boot of the kexeced kernel, the driver verifies that the data was properly preserved.
Signed-off-by: Mike Rapoport (Microsoft) rppt@kernel.org
(...)
--- /dev/null +++ b/tools/testing/selftests/kho/init.c @@ -0,0 +1,100 @@ +// SPDX-License-Identifier: GPL-2.0
+#ifndef NOLIBC
This is not necessary anymore, nolibc now provides these headers. You can keep it if you want, though.
+#include <errno.h> +#include <stdio.h> +#include <unistd.h> +#include <fcntl.h> +#include <syscall.h>
This should be <sys/syscall.h>.
+#include <sys/mount.h> +#include <sys/reboot.h> +#endif
(...)
--- /dev/null +++ b/tools/testing/selftests/kho/vmtest.sh @@ -0,0 +1,183 @@
(...)
+function mkinitrd() {
- local kernel=$1
- mkdir -p "$initrd_dir"/{dev,debugfs,proc}
- sudo mknod "$initrd_dir/dev/console" c 5 1
You could generate the initrd with usr/gen_init_cpio or usr/gen_initramfs.sh which would remove the need to use sudo. Especially as I think the mknod should fail if $TMP is mounted 'nodev'.
- "$CROSS_COMPILE"gcc -s -static -Os -nostdinc -I"$headers_dir/include" \
-fno-asynchronous-unwind-tables -fno-ident -nostdlib \-include "$test_dir/../../../include/nolibc/nolibc.h" \
If you drop the #ifdef NOLIBC, use '-I "$test_dir/../../../include/nolibc/' here instead. Or better, $kernel_dir/tools/include/nolibc/.
-o "$initrd_dir/init" "$test_dir/init.c" \- cp "$kernel" "$initrd_dir/kernel"
- pushd "$initrd_dir" &>/dev/null
- find . | cpio -H newc --create > "$initrd" 2>/dev/null
- popd &>/dev/null
+}
(...)
Thomas