Among the many changes to find with Linux 5.5 are support for the Raspberry Pi 4 / BCM2711, various performance changes still being explored, support for reporting NVMe drive temperatures, a new Logitech keyboard driver, AMD HDCP support for content protection, wake-on-voice support from Chromebooks, the introduction of KUnit for unit testing the kernel, new RAID1 modes that are quite exciting for Btrfs, and much more. Below is a more detailed look based upon our original monitoring and reporting.
- Continued improvements for the AMD Arcturus Vega-based GPU bring-up.
- AMDGPU HDCP support for Raven Ridge and newer.
- AMDKFD support for the POWER architecture but the ROCm POWER user-space patches are still pending.
- Continued Intel Gen12 / Tiger Lake graphics bring-up along with initial Intel Jasper Lake support.
- The Allwinner Cedrus video decode driver now supports HEVC/H.265.
- AMD OverDrive overclocking for Navi GPUs.
- Btrfs RAID1C3/RAID1C4 modes that allow three and four copies of data with Btrfs’ native RAID1 capabilities to offer more redundant support.
- Broadcom BCM2711 SoC support for the Raspberry Pi 4.
- KVM support for IBM POWER secure guests/VMs.
– KVM also now has nested 5-level page table support, Retpoline optimizations, and other Intel/AMD improvements for virtualization.
- SECCOMP support for RISC-V along with supporting the architecture’s “M-Mode” and other enhancements.
- Support for the new Loongson 3A variant for this MIPS-based processor.
- Intel 5-level paging support is enabled by default for supporting greater virtual and physical address space.
- Significant changes to the Linux kernel’s scheduler.
- Sanity checking of RdRand output in dealing with past buggy AMD CPUs / motherboard firmware.
- Late CPU microcode updates in parallel.
- Habana Labs preparing for future ASIC support.
- Working around an Arm Neoverse N1 bug.
- Support for vintage SGI Octane MIPS workstations.
Storage / File-Systems:
- NFS client support for cross-device offloaded copies for server-to-server transfers with NFSv4.2 server-side copy functionality.
- F2FS fixes.
- Many XFS changes.
– EXT4 now has direct I/O via iomap and FSCRYPT support for smaller block sizes.
– NVMe SSD drive temperatures are now conveniently exposed via sysfs rather than needing any special user-space components.
- A new HMEM driver for EFI specific purpose memory for cases like Intel Optane DC Persistent Memory.
- Microsoft exFAT file-system improvements for that driver that was added to staging last cycle.
- Support for toggling ASPM link states individually to offer better power-savings when a device may be connected where the driver by default is blocking ASPM.
- An Ice Lake USB power management improvement.
- The ability to boot the modem processor on the Snapdragon 835 SoC that is important not only for cellular but also WiFi support.
- A new Logitech keyboard driver.
- Another new hardware driver is the System76 ACPI Coreboot laptop driver. Also on the laptop front are Huawei support improvements.
- Thunderbolt improvements and officially deprecating the EEPROM driver highlight the char/misc changes.
- The new WFX WiFi driver for Silicon Labs WF200 ASICs.
- Wake-On-Voice support for select Chromebooks.
Security / Other:
- KUnit as an in-kernel unit testing means.
- The kernel concurrency sanitizer has been added for uncovering data race conditions.
- EFI RNG support as another source of entropy.
- Crypto improvements inspired by WireGuard’s Zinc crypto API. These changes in turn will allow WireGuard to land finally with Linux 5.6.
– Linux 5.5 livepatching infrastructure now tracks the system state for better patch handling/compatibility.
- Dropping of the SYSCTL system call.
- Reworked AMD IOMMU driver code.
- Continued Year 2038 fixes.
- VMs on Microsoft Hyper-V can finally hibernate.