What is kernel panic?
A kernel panic refers to a computer error from which the system's operating system (OS) cannot quickly or easily recover. It occurs when there is a low-level fatal error and the operating system's kernel is unable to fix it.
The term applies primarily to Unix-based operating systems such as Linux and BSD, and also to Mac OS X. The kernel panic error is similar to the blue screen of death (BSOD) error in Windows-based systems.
More about kernel panic
A kernel panic results in a failure to boot. It is used by an OS kernel to alert users to a problem, and prevent further issues once detected. During a kernel panic, the OS writes the contents of the kernel memory -- also known as a kernel dump -- to the disk. It also stops all CPU operations. To restart operations, the OS reboots automatically or waits for the user to reboot manually. The action taken depends on the OS configuration.
A kernel panic produces a message or set of messages on the computer display This message may include information about error type, code module running at the time of the error and loaded drives.
Kernel panic vs. system crash
A kernel panic is not the same as a system crash, although both can be annoying and even cause serious issues for the end user. In a kernel panic, the kernel terminates abnormally. In a system crash, the kernel forcefully terminates a software execution after detecting an abnormal condition. The goal is to minimize data loss or corruption in the device.
Causes of kernel panic
- a bug in the kernel (i.e., in a driver that is part of the kernel);
- failure or improper installation of random access memory (RAM) chips;
- hard disk damage or data corruption;
- defective or corrupted system file, processor or memory;
- unsupported hardware;
- failed or missing drives or partitions; and
- incompatible device drivers.
In Linux systems, kernel panic may be due to:
- corruption of the initramfs file that must load in RAM and point to the kernel (vmlinuz);
- if the initramfs file is not created properly for the specified kernel;
- if the kernel is not installed properly; and
- if recent OS patches are flawed.
Kernel panic in Linux
A Linux kernel panic is a system boot issue that occurs when the kernel can't load properly, and prevents the system from booting. It usually manifests as a black screen filled with code.
During a normal boot process, the kernel (vmlinuz) doesn't load directly. Instead, the initramfs file loads in the RAM. The file then points to the kernel which then results in OS booting. However, if the initramfs file is corrupted or deleted, it results in kernel panic. Such corruptions can occur due to recent OS updates or patches.
On Linux systems, "kernel oops" refers to a serious error that the OS can't handle. Even if the system continues to run, it may cause instability issues, and result in a full kernel panic. Not all kernel oops errors cause a kernel panic, although many do.
Kernel panic in macOS
Kernel panic in a Mac is due to a failure of the macOS kernel. It usually results in sudden system restarts or a display message that instructs the user to manually restart. If kernel panics happen frequently, they can disrupt user workflows, result in data loss, and even affect the health of the Mac system.
The most common reasons for kernel panic in a macOS are:
How to troubleshoot kernel panic in macOS
There are many reasons and causes for kernel panic errors. Here are several ways to troubleshoot and resolve the problem:
Update software and drivers
Out-of-date or corrupt software versions can cause problems for Mac systems, including kernel panic. To avoid the error, update all software and drivers. The process is straightforward:
- Navigate to the App Store
- Check for updates available for the system by clicking on 'Updates'
- Install updates
Check crash reports
Mac crash reports can provide useful insights about kernel panic issues. To access these reports, navigate to Applications > Utilities and access the log viewer named Console. Crash reports are displayed in the console. They contain information about kernel panics, including causes. This information helps technicians start the troubleshooting process.
Remove third-party kernel extensions
Kernel extensions that facilitate communication between hardware and the Mac can also cause kernel panic. To remove suspicious external kexts, users should:
- Open Terminal and type kextunload.
- Identify the suspicious kexts to be removed.
- Run the command: sudo kextunload /System/Library/Extensions/xxx, replacing xxx with the kext to be removed.
- Press Enter, type authentication password, and press Enter again.
Free up disk space
Freeing up disk space can help ensure the smooth processing of multiple apps and operations. Users can free up space by manually inspecting files and software and removing the assets that are not being used. Removing unused processes can also free up space in the memory and minimize the possibility of kernel panics.
Replace the RAM
Kernel panic is essentially an indication of the system's inability to execute some functions. This implies a lack of enough RAM or the presence of a malfunctioning RAM. Replacing the malfunctioned RAM can restore proper functioning and mitigate the risk of kernel panic.
Kernel panic in Windows
In Windows, kernel panic is typically characterized by the appearance of a BSOD error message stating that the system needs a restart. The error is usually caused by malfunctioning hardware or poorly optimized device drivers.
The steps to troubleshoot kernel panics in Windows are similar to the steps undertaken to troubleshoot kernel panics in Mac systems.
Kernel panic in Android
Although kernel panics are less probable in newer Android OS versions due to Android security updates and kernel optimizations, they can occur. Similar to other OSes, kernel panics in Android are usually hardware- or software-related. Other probable causes include faulty RAM, malfunctioning peripherals, plugins or programs. Updating to the latest Android version can help minimize the occurrence of kernel panics.