Boot Tracing Test Suite
=======================

This directory contains an automated test framework to verify kernel boot
tracing configurations (bootconfig, kernel command-line tracing options, and
persistent ring buffers) during early boot.

Overview
--------
The test runner (`run_boottime_test.sh`) constructs a lightweight initramfs with
busybox and a tracefs checker script from `tests/`, attaches optional bootconfigs
from `bootconfigs/` using the `bootconfig` tool, applies optional command-line
parameters from `cmdlines/`, boots the target kernel image under QEMU, and reports
results according to TAP version 13 format.

Test Specification Format
-------------------------
For each test script `tests/<name>.sh`, the harness dynamically detects:
- `bootconfigs/<name>.bconf` or `<name>.bconf`: Bootconfig configuration file.
- `cmdlines/<name>.cmdline` or `# CMDLINE: <opts>` header in script: Kernel boot parameters.
- `qemuopts/<name>.qemuopts` or `# QEMUOPTS: <opts>` header in script: Additional QEMU CLI arguments.
- `# APPLETS: <applets>` header in script: Additional BusyBox applet symlinks to create in initramfs.
- `# REBOOT: 1` header in script: Multi-boot reboot/crash test mode (omits `-no-reboot` and doubles timeout).

Required Tools
--------------
- Host Architecture: x86 (x86_64/i686/i386/x86; tests skip on non-x86 hosts)
- `qemu-system-x86_64` (or custom QEMU executable)
- `busybox` (host binary at `/usr/bin/busybox` or custom path)
- `bootconfig` (compiled from `tools/bootconfig/bootconfig` or in PATH)
- `file` (standard file architecture identifier)
- `cpio` (standard archiver)
- `timeout` (standard coreutils execution timer)

Required Kernel Configurations
------------------------------
The kernel binary under test must be compiled with:
- `CONFIG_BOOT_CONFIG=y`
- `CONFIG_BOOTTIME_TRACING=y`
- `CONFIG_MAGIC_SYSRQ=y` (for guest reboot and poweroff)

Additional feature-specific config options enable respective testcases:
- `CONFIG_KPROBE_EVENTS=y` (for kprobe tests)
- `CONFIG_SYNTH_EVENTS=y`  (for synthetic event tests)
- `CONFIG_EPROBE_EVENTS=y` (for eprobe tests)
- `CONFIG_FPROBE_EVENTS=y` (for fprobe and tracepoint probe tests)
- `CONFIG_FUNCTION_TRACER=y` (for tracer options)
- `CONFIG_RESERVE_MEM=y` (for persistent ring buffer tests)

Usage
-----
To run all test cases with a compiled kernel image:

  $ ./run_boottime_test.sh -k /path/to/bzImage

To run a specific test case (e.g. `01-kprobe`):

  $ ./run_boottime_test.sh -k /path/to/bzImage -t 01-kprobe

Customizing Tool Paths:

  $ ./run_boottime_test.sh -b /path/to/bootconfig \
                         -k /path/to/bzImage \
                         -q /path/to/qemu-system-x86_64 \
                         -B /path/to/busybox

Environment Variables
---------------------
Tool locations and kernel paths can also be set via environment variables:
- `BOOTCONFIG`: Path to the `bootconfig` tool
- `KERNEL`: Path to the `bzImage` kernel binary
- `QEMU`: Path to the QEMU binary
- `BUSYBOX`: Path to the `busybox` binary
- `LOGDIR`: Directory path to preserve QEMU execution log files