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Message-ID: <aSQPNuFIv0rRr2tp@kernel.org>
Date: Mon, 24 Nov 2025 09:54:30 +0200
From: Mike Rapoport <rppt@...nel.org>
To: Pasha Tatashin <pasha.tatashin@...een.com>
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Subject: Re: [PATCH v7 19/22] selftests/liveupdate: add test infrastructure
and scripts
On Sat, Nov 22, 2025 at 05:23:46PM -0500, Pasha Tatashin wrote:
> Subject: [PATCH v7 19/22] selftests/liveupdate: add test infrastructure and scripts
Maybe ^ end to end
> Add the testing infrastructure required to verify the liveupdate
> feature. This includes a custom init process, a test orchestration
> script, and a batch runner.
And say here that it's end to end test.
> The framework consists of:
>
> init.c:
> A lightweight init process that manages the kexec lifecycle.
> It mounts necessary filesystems, determines the current execution
> stage (1 or 2) via the kernel command line, and handles the
> kexec_file_load() sequence to transition between kernels.
>
> luo_test.sh:
> The primary KTAP-compliant test driver. It handles:
> - Kernel configuration merging and building.
> - Cross-compilation detection for x86_64 and arm64.
> - Generation of the initrd containing the test binary and init.
> - QEMU execution with automatic accelerator detection (KVM, HVF,
> or TCG).
>
> run.sh:
> A wrapper script to discover and execute all `luo_*.c`
> tests across supported architectures, providing a summary of
> pass/fail/skip results.
>
> Signed-off-by: Pasha Tatashin <pasha.tatashin@...een.com>
> ---
> tools/testing/selftests/liveupdate/init.c | 174 ++++++++++
> .../testing/selftests/liveupdate/luo_test.sh | 296 ++++++++++++++++++
> tools/testing/selftests/liveupdate/run.sh | 68 ++++
> 3 files changed, 538 insertions(+)
> create mode 100644 tools/testing/selftests/liveupdate/init.c
> create mode 100755 tools/testing/selftests/liveupdate/luo_test.sh
> create mode 100755 tools/testing/selftests/liveupdate/run.sh
>
...
> +static int is_stage_2(void)
> +{
> + char cmdline[COMMAND_LINE_SIZE];
> + ssize_t len;
> + int fd;
> +
> + fd = open("/proc/cmdline", O_RDONLY);
> + if (fd < 0)
> + return 0;
> +
> + len = read(fd, cmdline, sizeof(cmdline) - 1);
> + close(fd);
> +
> + if (len < 0)
> + return 0;
Shouldn't we bail out of the test if read of command line failed?
> +
> + cmdline[len] = 0;
> +
> + return !!strstr(cmdline, "luo_stage=2");
> +}
> +
...
> +function cleanup() {
> + local exit_code=$?
> +
> + if [ -z "$workspace_dir" ]; then
> + ktap_finished
> + return
> + fi
> +
> + if [ $exit_code -ne 0 ]; then
> + echo "# Test failed (exit code $exit_code)."
> + echo "# Workspace preserved at: $workspace_dir"
> + elif [ "$KEEP_WORKSPACE" -eq 1 ]; then
> + echo "# Workspace preserved (user request) at: $workspace_dir"
> + else
> + rm -fr "$workspace_dir"
> + fi
> + ktap_finished
exit $exit_code
> +}
...
> +function build_kernel() {
> + local build_dir=$1
> + local make_cmd=$2
> + local kimage=$3
> + local target_arch=$4
> +
> + local kconfig="$build_dir/.config"
> + local common_conf="$test_dir/config"
> + local arch_conf="$test_dir/config.$target_arch"
> +
> + echo "# Building kernel in: $build_dir"
> + $make_cmd defconfig
> +
> + local fragments=""
> + if [[ -f "$common_conf" ]]; then
> + fragments="$fragments $common_conf"
> + fi
Without this CONFIG_LIVEUPDATE won't be set
> +
> + if [[ -f "$arch_conf" ]]; then
> + fragments="$fragments $arch_conf"
> + fi
> +
> + if [[ -n "$fragments" ]]; then
> + "$kernel_dir/scripts/kconfig/merge_config.sh" \
> + -Q -m -O "$build_dir" "$kconfig" $fragments >> /dev/null
> + fi
I believe you can just
cat $common_conf $fragments > $build_dir/.config
make olddefconfig
without running defconfig at the beginning
It will build faster, just make sure to add CONFIG_SERIAL_ to $arch_conf
> + $make_cmd olddefconfig
> + $make_cmd "$kimage"
> + $make_cmd headers_install INSTALL_HDR_PATH="$headers_dir"
> +}
> +
> +function mkinitrd() {
> + local build_dir=$1
> + local kernel_path=$2
> + local test_name=$3
> +
> + # 1. Compile the test binary and the init process
Didn't find 2. ;-)
Don't think we want the numbering here, plain comments are fine
> + "$CROSS_COMPILE"gcc -static -O2 \
> + -I "$headers_dir/include" \
> + -I "$test_dir" \
> + -o "$workspace_dir/test_binary" \
> + "$test_dir/$test_name.c" "$test_dir/luo_test_utils.c"
This will have hard time cross-compiling with -nolibc toolchains
> +
> + "$CROSS_COMPILE"gcc -s -static -Os -nostdinc -nostdlib \
> + -fno-asynchronous-unwind-tables -fno-ident \
> + -fno-stack-protector \
> + -I "$headers_dir/include" \
> + -I "$kernel_dir/tools/include/nolibc" \
> + -o "$workspace_dir/init" "$test_dir/init.c"
This failed for me with gcc 14.2.0 (Debian 14.2.0-19):
/home/mike/git/linux/tools/testing/selftests/liveupdate/init.c: In function ‘run_test’:
/home/mike/git/linux/tools/testing/selftests/liveupdate/init.c:111:65: error: initializer element is not constant
111 | static const char *const argv[] = {TEST_BINARY, stage_arg, NULL};
| ^~~~~~~~~
/home/mike/git/linux/tools/testing/selftests/liveupdate/init.c:111:65: note: (near initialization for ‘argv[1]’)
/home/mike/git/linux/tools/testing/selftests/liveupdate/init.c:113:37: error: passing argument 2 of ‘execve’ from incompatible pointer type [-Wincompatible-pointer-types]
113 | execve(TEST_BINARY, argv, NULL);
| ^~~~
| |
| const char * const*
In file included from /home/mike/git/linux/tools/testing/selftests/liveupdate/init.c:16:
/usr/include/unistd.h:572:52: note: expected ‘char * const*’ but argument is of type ‘const char * const*’
572 | extern int execve (const char *__path, char *const __argv[],
| ~~~~~~~~~~~~^~~~~~~~
> +
> + cat > "$workspace_dir/cpio_list_inner" <<EOF
> +dir /dev 0755 0 0
> +dir /proc 0755 0 0
> +dir /debugfs 0755 0 0
> +nod /dev/console 0600 0 0 c 5 1
Don't you need /dev/liveupdate node?
> +file /init $workspace_dir/init 0755 0 0
> +file /test_binary $workspace_dir/test_binary 0755 0 0
> +EOF
> +
> + # Generate inner_initrd.cpio
> + "$build_dir/usr/gen_init_cpio" "$workspace_dir/cpio_list_inner" > "$workspace_dir/inner_initrd.cpio"
> +
> + cat > "$workspace_dir/cpio_list" <<EOF
> +dir /dev 0755 0 0
> +dir /proc 0755 0 0
> +dir /debugfs 0755 0 0
> +nod /dev/console 0600 0 0 c 5 1
And here as well.
> +file /init $workspace_dir/init 0755 0 0
> +file /kernel $kernel_path 0644 0 0
> +file /test_binary $workspace_dir/test_binary 0755 0 0
> +file /initrd.img $workspace_dir/inner_initrd.cpio 0644 0 0
> +EOF
> +
> + # Generate the final initrd
> + "$build_dir/usr/gen_init_cpio" "$workspace_dir/cpio_list" > "$initrd"
> + local size=$(du -h "$initrd" | cut -f1)
> +}
> +
> +function run_qemu() {
> + local qemu_cmd=$1
> + local cmdline=$2
> + local kernel_path=$3
> + local serial="$workspace_dir/qemu.serial"
> +
> + local accel="-accel tcg"
> + local host_machine=$(uname -m)
> +
> + [[ "$host_machine" == "arm64" ]] && host_machine="aarch64"
> + [[ "$host_machine" == "x86_64" ]] && host_machine="x86_64"
> +
> + if [[ "$qemu_cmd" == *"$host_machine"* ]]; then
> + if [ -w /dev/kvm ]; then
> + accel="-accel kvm"
Just pass both kvm and tcg and let qemu complain.
> + fi
> + fi
> +
> + cmdline="$cmdline liveupdate=on panic=-1"
> +
> + echo "# Serial Log: $serial"
> + timeout 30s $qemu_cmd -m 1G -smp 2 -no-reboot -nographic -nodefaults \
> + $accel \
> + -serial file:"$serial" \
> + -append "$cmdline" \
> + -kernel "$kernel_path" \
> + -initrd "$initrd"
> +
> + local ret=$?
> +
> + if [ $ret -eq 124 ]; then
> + fail "QEMU timed out"
> + fi
> +
> + grep "TEST PASSED" "$serial" &> /dev/null || fail "Liveupdate failed. Check $serial for details."
> +}
--
Sincerely yours,
Mike.
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