Linux 7.4-rc2 brings FAT32 sync-mount speedup, AMDGPU HDMI 2.2 FRL fixes

Linus Torvalds released Linux 7.4-rc2, the second weekly candidate toward the stable kernel expected by late December 2026. The release follows an unusually large -rc1 and contains driver fixes for AMDGPU HDMI 2.2 FRL (Fixed Rate Link) operation, a significant optimization for FAT32 filesystems on synchronous mounts, and corrections to AMD PerfOpt behavior for Radeon integrated graphics. Torvalds also noted that BPF maintainer Alexei Starovoitov reports AI-generated fixes for that subsystem now arriving faster than new bug reports, suggesting a possible inflection point in managing machine-contributed kernel patches.

The diffstat is dominated by automated Coccinelle scripting updates spread across thousands of files, but masking those reveals a conventional distribution: one-third drivers (GPU, networking, sound), one-third networking and BPF, and one-third filesystems, memory management, and architecture code. The release also corrects faulty BHI (Branch History Injection) mitigation selection for certain kernel configurations and addresses what Torvalds described as "nasty long standing bugs" in core memory management.

Driver, filesystem, and security fixes in 7.4-rc2

• FAT32 filesystem: Significant optimization specifically for synchronous mounts, reducing performance overhead when data integrity guarantees require immediate disk writes.
• AMDGPU display: Driver fixes for HDMI 2.2 FRL (Fixed Rate Link) operation, addressing signaling and compatibility issues with next-generation display connectivity.
• AMD Radeon iGPU: Adjustments to the PerfOpt performance optimization feature, refining power and frequency behavior for integrated Radeon graphics.
• Memory management: Resolution of multiple long-standing bugs in core MM code affecting page allocation, reclaim, or mapping behavior.
• Security mitigations: Fix for incorrect BHI (Branch History Injection) mitigation selection on certain kernel build configurations, ensuring proper Spectre-variant protection is applied.

Why it matters

The FAT32 synchronous mount improvement directly benefits embedded systems, removable media workflows, and legacy compatibility layers where sync mounts remain common. For Linux gaming and desktop users, the AMDGPU HDMI 2.2 FRL fixes ensure proper operation with high-bandwidth displays on RDNA-class hardware, while the Radeon iGPU PerfOpt adjustments improve power efficiency on AMD mobile and APU platforms. Distribution maintainers should note the BHI mitigation fix for security-hardened builds, and the ongoing volume of AI-generated patches signals a structural shift in kernel development workflows that may affect review bandwidth and patch quality standards across the ecosystem.