Recommended Free Tools
The easiest way to start debugging the Linux kernel is to match the tool to the evidence you need: enable supported debug messages for a narrow code-path question, trace execution when patterns or timing matter, and use KGDB when you need to inspect live kernel state with GDB. You can practise the latter in QEMU/KVM; a serial adapter is only needed for a compatible serial-based setup.
Choose the method that fits the failure
Start by describing what you need to learn: whether a value is wrong, whether a code path runs, what happens over time, or what the kernel’s state is at the moment of a crash. The Linux kernel’s general debugging advice notes that the right tools depend on the issue; there is no single switch that makes every kernel problem easy to diagnose.
| Question | Good starting point | What it can show |
|---|---|---|
| Does this supported debug statement run, and what does it report? | Dynamic debug | Selected pr_debug() and dev_dbg() messages. |
| What call pattern or behavior unfolds over time? | Tracing, such as ftrace | Execution and system-behavior patterns. |
| What are the kernel’s live variables, registers, or call stack? | KGDB with GDB | Interactive, source-level inspection of a target kernel. |
| Do I need basic inspection from a console? | KDB | Console-oriented inspection, including memory, registers, processes, logs, and breakpoints. |
These tools answer different questions and can be combined as an investigation progresses. For driver-specific considerations, consult the kernel’s driver development debugging guide.
Use dynamic debug for targeted messages
Dynamic debug selectively enables supported pr_debug(), dev_dbg(), and related call sites, letting you turn on useful messages without enabling every such statement everywhere. It requires a kernel built with CONFIG_DYNAMIC_DEBUG. It cannot switch on arbitrary logging mechanisms or messages that do not use supported dynamic-debug call sites. See the kernel’s userspace debugging advice for its scope and usage.
The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
Choose it when a specific event or value is the missing evidence and the effects of logging do not compromise the behavior you’re trying to observe. If the failure is sensitive to timing, added messages can change what you see; prefer tracing when execution patterns matter.
Use tracing when patterns or timing matter
Tracing helps reveal execution patterns and system behavior over time. The kernel’s Linux Tracing Technologies Guide covers the available tracing facilities, including ftrace. Use this approach when a sequence of calls, an intermittent event, or timing behavior is more informative than a single printed message.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
The kernel’s debugging advice also points to trace_printk() as an option when ordinary printk() changes timing enough to obscure a fault: it writes to the trace file rather than the kernel log. It is a tracing aid, not a replacement for choosing the right trace events or understanding their output.
Use KGDB for interactive source-level inspection
KGDB connects GDB on a development machine to a target running the kernel under investigation. The Linux kernel documentation describes KGDB this way: “Kgdb is intended to be used as a source level debugger for the Linux kernel.” With GDB, you can stop execution and inspect source-level state, which is useful when logs and traces do not explain what the kernel is doing at a particular point.
Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsRank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
Setup depends on the kernel configuration, architecture, and available I/O drivers. The official KGDB, KDB, and debugger internals guide recommends enabling debug information to obtain useful symbols and says frame pointers are helpful, though not required. Check that guide for the kernel version and target architecture you actually use; configuration and breakpoint behavior are not universal.
Choose KDB for console-oriented checks
KDB is a simpler, shell-style debugger interface available through a system or serial console. It can help inspect memory, registers, process lists, logs, and breakpoints, but it is not a full source-level GDB session. Choose it when console access and basic state inspection are enough; choose KGDB when you need GDB’s source-level workflow.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
Practise in QEMU/KVM before requiring hardware
A virtual machine can provide a practical learning setup without making a dedicated hardware debugger the first requirement. The kernel’s GDB tutorial for debugging kernels and modules documents a QEMU/KVM route for using GDB with a running kernel. Follow the tutorial’s setup for the kernel and environment you are using.
A physical serial cable or adapter is only relevant when the target and KGDB setup use a compatible serial connection. Verify the machine’s available interfaces and the chosen debugging workflow before buying hardware; a serial adapter is not a universal kernel-debugging prerequisite.
Quick Recap
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
A simple progression for a first investigation
- Describe the symptom. Decide whether you need a value or event, an execution pattern, or a snapshot of live state.
- Check the available evidence. For a supported debug call site, confirm that the kernel has
CONFIG_DYNAMIC_DEBUG; for source-level work, check the target’s KGDB configuration, architecture, and I/O path. - Start with the least disruptive useful method. Turn on selected messages for a narrow question, or use tracing when the sequence or timing is central.
- Escalate to interactive inspection when needed. Use KGDB with GDB for source-level state, or KDB for console-oriented checks. A QEMU/KVM setup is a documented way to practise the GDB workflow.
- Reassess if the observation changes the fault. If added logging alters timing, switch to tracing rather than assuming the failure has disappeared.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
