3.20 merge window part 2

As of this writing, 7,849 non-merge changesets have been pulled into the mainline repository for this development cycle; about 4,200 of those have come in since last week's summary was written. Some of the more interesting user-visible changes found in those 4,200 patches include:

• The parallel NFS (pNFS) subsystem has gained support for the under-development FlexFile layout. This layout allows file metadata to be stored in a different location from the file contents.

• The persistent storage subsystem can optionally provide a new special file (/dev/pmsg0) allowing user-space programs to log data into the store.

• The Smack security module can now interface with the netfilter system, using security labels to filter packets.

• The ubifs filesystem now has multiqueue block layer support (increasing its performance) and support for security.* extended attributes (making security module support possible).

• The Android binder code has been equipped with security hooks allowing it to be brought under SELinux (or any other security module) policies.

• The I2O bus subsystem has been moved into the staging directory with the idea of removing it from the kernel entirely in the near future. As far as the developers can tell, nobody is using this code; if that impression is mistaken, now would be a good time to say something.

• See this posting for a description of the changes to the Intel graphics driver in this development cycle.

• The nonvolatile memory support patches have been merged, making it possible to host filesystems in persistent memory with good performance.

• The PA-RISC architecture is no longer able to run 32-bit HP-UX binaries. The number of users upset by this change is expected to be small.

• The lazytime filesystem option (with support in ext4, initially) has been merged. Lazytime allows accurate tracking of file access times without creating lots of write I/O to the filesystem.

• New hardware support includes:
  • Systems and processors: IBM s/390 z13 processors, Artesyn MVME2500 single board computers, Conexant Digicolor SoCs, NVIDIA Tegra132 SoCs, Freescale LS2085A SoCs, and Mediatek MT65xx & MT81xx ARMv8 SoCs,

  • Graphics: ATMEL HLCDC display controllers and Samsung Exynos7 SoC display controllers. Also, the "fbtfb" subsystem has been added to the staging tree; it provides support for a wide range of small TFT LCD display modules.

  • Industrial I/O: Solteam Opto JSA1212 proximity and ambient light sensors, Kionix KMX61 6-axis accelerometer/magnetometers, Freescale MMA9551L intelligent motion sensors, Freescale MMA9553L intelligent pedometers, Semtech SX9500 proximity sensors, Capella Microsystems cm3232 ambient light sensors, Qualcomm SPMI PMIC voltage analog-to-digital converters (ADCs), Cosmic Circuits 10001 ADCs, and Samsung Sensorhub microcontroller units.

  • Miscellaneous: APM X-Gene GPIO standby controllers, Fujitsu MB86S7x GPIO controllers, Altera mailbox units, Version 2.0 Trusted Platform Modules (TPMs), Abracon AB-RTCMC-32.768kHz-B5ZE-S3 realtime clocks, Armada 38x Marvell SoC realtime clocks, ETRAX FS serial ports, Alphascale ASM9260 timers, Rockchip rk3288 timers, Conexant Digicolor timers, and Dallas/Maxim DS1685 realtime clocks.

  • Pin control: Allwinner A31s SoC pin controllers, Amlogic Meson SoC pin controllers, and Xilinx Zynq pin controllers, Qualcomm 8916 pin controllers.

  • USB: Rockchip USB2 PHYs and NXP ISP1761 USB device controllers.

Changes visible to kernel developers include:

• The ARM I/O memory-management unit (IOMMU) layer has a new, generic page-table management API. See drivers/iomu/io-pgtable.c and io-pgtable.h for an overview of this API.

• The LED subsystem now has a new device class for LEDs operating in the "flash" (as in camera flash) mode.

• The kernel address sanitizer (KASan) has been merged. KASan monitors kernel memory references in an attempt to catch code reaching into memory it has no business touching. For now, KASan only works on the x86_64 architecture, and memory hotplug must be disabled.

• Developers working with the GDB debugger may want to look at the new set of helper scripts added under scripts/gdb.

• The printk() family of functions has a new format type (%pb) for the printing of bitmaps. The number of bits in the bitmap must be specified as the field width in the format string.

So far, this development cycle seems to be a relatively slow one, as was suggested before the merge window opened. Still, the emphasis should be on "relatively"; nearly 8,000 patches is not a small number.

The version number for this kernel is yet to be determined. Linus ran a poll on Google+ that came out in favor of calling it 4.0, but he has not said what he will actually do. Tune in next week for the final changes that come in for this cycle and, presumably, an answer to the naming question.

Index entries for this article
Kernel	Releases/4.0

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