A race condition solved by staying open a little longer
In the steady rhythm of open-source stewardship, the KDE team has released Plasma 6.6.5 — not as a leap forward, but as an act of repair. The release quietly addresses a cluster of performance regressions introduced when NVIDIA's 595 driver series disrupted the fragile harmony between hardware and the Wayland display protocol, particularly for users running multi-GPU systems on distributions like Fedora and CachyOS. It is the kind of release that reminds us that progress in software is not only made in grand gestures, but in the patient, unglamorous work of keeping things whole.
- NVIDIA's 595 driver series introduced performance regressions that broke multi-GPU workflows on Wayland, leaving users across multiple Linux distributions with degraded or unstable desktop experiences.
- The disruption exposed a deeper architectural fragility: KDE's method of copying data between GPUs relied on OpenGL, a legacy approach ill-suited to the demands of modern multi-GPU configurations.
- Color rendering on NVIDIA hardware and HDR display logic were also misbehaving — the system incorrectly offered a CI/DCI display option during HDR mode, undermining the very brightness control HDR depends on.
- Spectacle, KDE's screenshot tool, was silently failing users by closing too quickly to complete clipboard operations — a small but daily frustration now resolved by keeping the app alive just long enough to finish the job.
- KDE 6.6.5 lands as a deliberate stabilization bridge, clearing the immediate wreckage while the team finalizes 6.7 — a more ambitious release that rewrites multi-GPU handling in Vulkan and revives beloved themes Air and Oxygen.
KDE Plasma 6.6.5 arrived this week as a focused maintenance release, timed just ahead of the more ambitious 6.7 update due in mid-June. Rather than introducing new features, the KDE team directed the release entirely at a set of performance regressions that surfaced after NVIDIA shipped its 595 driver series.
The most consequential fix targets a Wayland bug that hit multi-GPU systems particularly hard. Users on CachyOS and Fedora both encountered the issue, which traced back to how KDE was transferring data between graphics processors using OpenGL. The team has already rewritten that section for 6.7 using Vulkan — a more modern API — but 6.6.5 addresses the immediate fallout in the meantime.
The release also corrects color rendering inconsistencies on NVIDIA hardware and fixes a logic error in HDR display handling, where the system was incorrectly surfacing a CI/DCI external display option even when HDR mode was active — a setting that conflicts with HDR's need to govern its own brightness levels.
A quieter but practical fix landed in Spectacle, KDE's screenshot utility. The tool had been closing too quickly after captures, cutting off the clipboard operation before it could complete. The solution was straightforward: keep Spectacle open just long enough for the system to finish writing the image to the clipboard.
With these repairs in place, 6.6.5 serves as a stabilizing bridge toward KDE 6.7, scheduled for June 16, 2026. That release promises considerably more: a new CSS-based Union style engine, the return of the Air and Oxygen themes, improved Wayland session restoration, and the Vulkan-powered multi-GPU rewrite that should prevent this class of driver-induced regression from recurring.
KDE Plasma 6.6.5 arrived this week as a maintenance release, arriving just ahead of the larger 6.7 update scheduled for mid-June. The new version is lean by design—no sweeping features, no architectural overhauls. Instead, the KDE team focused the release entirely on patching problems that had accumulated since the last version, with particular attention to a set of performance regressions that emerged after NVIDIA released its 595 driver series.
The most significant of these fixes addresses a bug that had been plaguing users on Wayland, the modern display protocol that many Linux distributions are gradually moving toward. The problem appeared across multiple systems—users on CachyOS and Fedora both reported the issue—and seemed to hit hardest in multi-GPU setups, where a single machine runs multiple graphics processors. The underlying cause involved how KDE was copying data between GPUs, a low-level operation that had been handled through OpenGL. For the upcoming 6.7 release, the developers have rewritten this entire section to use Vulkan instead, a more modern graphics API that should prevent similar issues from recurring.
Beyond the multi-GPU problem, the 6.6.5 release tackled color rendering on NVIDIA hardware. The update improves how colors are handled on NVIDIA GPUs, addressing a class of visual inconsistencies that users had been experiencing. The release also corrected an issue with HDR displays, where the system was offering users a CI/DCI external display option even when HDR was enabled. That option should never appear in HDR mode, since HDR itself needs to maintain control over brightness levels for the technology to function as intended.
Another practical fix involved Spectacle, KDE's built-in screenshot utility. Users had been reporting that after taking a screenshot, the image would not properly copy to the clipboard—a frustrating limitation for anyone trying to quickly capture and share part of their screen. The developers solved this by adjusting Spectacle to remain open briefly after a screenshot is taken, giving the system enough time to complete the clipboard operation before the application closes.
These fixes arrive as a stabilization effort before the larger 6.7 release, which is scheduled to launch on June 16, 2026. That upcoming version is expected to be substantially more ambitious. It will introduce a new Union style engine built on CSS rather than the older approach, bringing back two beloved themes—Air and Oxygen—that had been retired in earlier versions. Session restoration under Wayland, a feature that lets users pick up where they left off after logging back in, is also receiving improvements. For now, 6.6.5 serves as a bridge: addressing the immediate pain points that emerged from recent driver changes while the team prepares the next major milestone.
Citações Notáveis
The multi-GPU copy code has been rewritten to use Vulkan instead of OpenGL for the 6.7 release— KDE development team (via changelog)
A Conversa do Hearth Outra perspectiva sobre a história
Why does an NVIDIA driver update cause problems in KDE? Aren't they separate projects?
They are, but they have to work together. When NVIDIA changed how its 595 driver handles GPU operations, it exposed assumptions KDE had been making about how that communication would work. Multi-GPU systems were hit hardest because the code path for copying data between GPUs became unreliable.
So this is a compatibility issue, not a bug in KDE itself?
It's both. KDE's code was correct in isolation, but it relied on OpenGL, which is older and less predictable for this kind of work. The real fix is moving to Vulkan, which is what 6.7 will do.
Why not just wait for 6.7 instead of releasing 6.6.5?
Because people are using Plasma now. Some users have multi-GPU setups that are completely broken on Wayland right now. You can't ask them to wait a month. 6.6.5 patches the immediate wound while 6.7 does the deeper surgery.
The Spectacle fix sounds simple—why was it broken in the first place?
Timing. The application was closing too fast, before the clipboard operation finished. It's a race condition. The fix is inelegant but it works: just stay open a little longer.
What does the HDR display fix actually do?
It removes an option that shouldn't exist. When HDR is on, the system needs to control brightness itself. Offering users a CI/DCI option would let them override that, which breaks HDR. It's a safety guard.
Is 6.6.5 worth installing if you don't have an NVIDIA GPU?
Probably. The color handling improvements and Spectacle fix help everyone. But if you're on AMD or Intel graphics and not using Wayland, you're not getting the main benefit.