Linux 5.5 Released With Many Hardware Support Improvements

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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.

Other Hardware:

  • 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.

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