The Linux kernel development cycle continues with the release of Linux 6.19-rc4, the fourth release candidate in the lead-up to the final 6.19 stable kernel. As with previous RC builds, this release is aimed squarely at developers, testers, and early adopters who help identify bugs and regressions before the kernel is finalized.

Release candidates are not feature drops — they are checkpoints. And rc4 reflects exactly that role.

What Does rc4 Mean in the Kernel Cycle?

By the time the fourth release candidate arrives, the merge window is long closed. That means all major features for Linux 6.19 are already in place, and the focus has shifted entirely to:

• Fixing bugs introduced earlier in the cycle

• Addressing regressions reported by testers

• Refining drivers, subsystems, and architecture-specific code

In other words, rc4 is about stability and correctness, not surprises.

What’s Changed in Linux 6.19-rc4

While rc releases don’t usually headline major features, they do include a steady stream of important fixes across the kernel tree.

Driver and Hardware Fixes

Many of the changes in rc4 focus on hardware support, including:

• GPU driver fixes for stability and edge-case behavior

• Networking device driver cleanups

• Updates for input devices and platform-specific drivers

These changes help ensure Linux continues to run reliably across a wide range of systems, from desktops and laptops to servers and embedded hardware.

Filesystems and Storage

Several filesystems see incremental fixes in this release, addressing corner cases, error handling, and consistency issues. Storage-related updates also touch block-layer code and device-mapper components, helping improve reliability under load.

Architecture-Specific Updates

As usual, rc4 includes fixes tailored to specific CPU architectures, such as:

• x86 refinements

• ARM and ARM64 cleanups

• RISC-V and other platform-specific adjustments

These changes may not affect all users directly, but they’re crucial for maintaining Linux’s broad hardware compatibility.

Regression Fixes and Testing Feedback

A large portion of rc4 is dedicated to resolving regressions reported by testers running earlier release candidates. This includes:

• Fixes for boot issues on certain configurations

• Corrections for performance regressions

• Cleanup of warnings and build errors