I started with Ubuntu and later tried Linux Mint because I wanted a stable system for everyday work. Both worked well at first, but after updating, my laptop's display brightness became stuck at 100%. The machine uses Intel integrated graphics, so I wasn't expecting a graphics compatibility problem.
After trying several fixes, I eventually resolved the issue by booting an older 6.x kernel instead of the newer 7.x kernel. I'm not an advanced Linux user, though, and I'm worried that staying on an older kernel could leave me without important security updates or other fixes.
Is using an older kernel actually a security risk? Are older kernels still maintained with security patches, and could this brightness problem be specific to the newer kernel rather than Linux in general?
5 Answers
This sounds like a regression in the newer kernel or a laptop-specific configuration issue. Brightness control can depend on firmware, ACPI behavior, graphics drivers, and kernel parameters, so changing kernels can appear to fix it even when the underlying cause is hardware compatibility. Before giving up, it would be worth checking the other installed kernels, collecting logs, and reporting the problem with the laptop model and kernel versions.
For Ubuntu-based systems, the kernel supplied with a particular release is maintained by the distribution for that release's supported lifetime. Security fixes are commonly backported, so an older-looking kernel version is not automatically insecure. You may miss newer features and hardware support, but you can still receive security updates until the release reaches end of life.
Switching to another distribution may or may not change the result. Fedora and Ubuntu-based systems can carry different kernel versions and patches, so the bug might be absent in one and present in another, but the laptop's firmware and hardware support still matter. The most useful details for investigating it would be the exact laptop model, distribution version, kernel versions, and relevant display or ACPI logs.
Kernel version numbers can be misleading. Linux also maintains several long-term-support branches for years, and production systems often deliberately use older kernels because they are stable. The important thing is whether your distribution is still providing updates for that kernel, not whether it has the newest version number.
You can usually keep multiple kernels installed and select a known-good one from the boot menu while testing newer releases. If the older kernel belongs to a supported distribution release or an LTS branch, using it is generally reasonable. It is different from running an abandoned, unsupported kernel with no security maintenance.
I spent most of a weekend trying different fixes, and downgrading the kernel was the only one that worked. My main concern was that I didn't understand whether an older kernel automatically meant weaker security, so I went back to Windows rather than take the risk.