The 3.19 merge window opens

As of this writing, the merge window for the 3.19 development cycle has gotten off to a bit of a slow start; less than 2000 non-merge changesets have been pulled into the mainline repository so far. As can be seen from the lists below, though, that is still enough for some interesting new code to make its way into the kernel.

User-visible changes for 3.19 include:

• Support for Intel's MPX technology has been added to the kernel. MPX-enabled processors (which are still mostly unobtainable) can perform bounds-checking on memory references, presumably catching a lot of bugs and blocking the exploitation of buffer-overflow vulnerabilities. Using this feature requires providing the processor with a lot of information about the acceptable bounds for each memory reference, though, so full adoption is likely to take time.

• The device mapper "thin provisioning" target has seen some significant performance improvements, mostly having to do with aggregating I/O operations to the same block before issuing them to the underlying device.

• The kernel now has support for Altera's "Nios II" processor.

• The arm64 architecture has gained support for the secure computing ("seccomp") subsystem.

• New hardware support includes:
  • Systems and processors: Broadcom IPROC architected systems-on-chip (SoCs), Amlogic Meson8 SoCs, Allwinner A80 SoCs, Samsung Exynos4415 SoCs, Freescale LS1021A SoCs, Alphascale ASM9260 SoCs, and AMD Seattle SoCs. Additionally, dozens of new systems are supported through device tree additions.

  • Block: Tekram DC390(T) and Am53/79C974 SCSI adapters and Western Digital WD7193/7197/7296 SCSI adapters.

  • Miscellaneous: Toshiba type A SD/MMC card interfaces, X-Powers AXP288 analog-to-digital converters, Diolan DLN2 USB-I2C/SPI/GPIO master adapters, Atmel high-end LCD controllers, Nuvoton NCT7802Y hardware monitoring chips, Richtek RT5033 regulators, and NVIDIA Tegra system memory management units.

Changes visible to kernel developers include:

• The Atmel AT91 subarchitecture has been completely converted over to the device tree mechanism. To celebrate, the developers removed all of the old board files for this family, reducing the size of the kernel by 24,000 lines of code.

• Work on the year 2038 problem continues. The internal functions do_settimeofday(), timekeeping_inject_sleeptime(), and mktime() now have 2038-safe replacements. In each case, the new version adds "64" to the name of the function and switches to the time64_t or timespec64 types for time representation. Now the process of deprecating the old versions and converting code can begin.

• Hierarchical interrupt domain support has been merged into the interrupt-handling core. This support is needed to properly represent complex hardware which has multiple interrupt controllers connected in complicated ways. See the new section added to Documentation/IRQ-domain.txt for a bit more information.

If the usual pattern holds, the merge window will remain open until December 21, when the first 3.19 prepatch will be released. As usual, LWN will track the changes merged during this merge window in subsequent articles; stay tuned.

Index entries for this article
Kernel	Releases/3.19

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