3.7 Merge window part 1

A mere 72 days after the beginning of the 3.6 development cycle, the process has started again with the opening of the 3.7 merge window. As of this writing, some 5540 non-merge changesets have been pulled into the mainline, with more to come. Some of the more interesting user-visible changes merged thus far include:

• The arm64 patch set, adding support for ARM's 64-bit "AARCH64" architecture, has been merged.

• The perf kvm tool has gained a "stat" command for analysis of event data. Extensive bash completion support for perf (for both commands and event names) has also been added.

• The new perf trace tool is meant to function like the strace utility, but with the ability to show events beyond system calls. This tool appears to be just getting started; the commit message reads "It gets stuck sometimes, but hey, it works sometimes too!"

• Applications on the s/390 architecture can now make use of the System zEC12 hardware transactional memory feature.

• Support for the Intel supervisor mode access prevention feature has been added.

• The CIFS filesystem now has complete SMB2.1 support; SMB2 is still marked as experimental, but that's a step forward from its previous "broken" status.

• The ARM subtree cleanup continues; the Tegra subarchitecture is now fully converted to the device tree mechanism. The unloved and unused Philips Nexperia PNX4008 subarchitecture support has been removed.

• Extended attributes are now implemented on the control directories for control groups. This is a Systemd-inspired feature allowing ancillary information to be attached to control groups.

• If non-hierarchical control group controllers are used with nested (hierarchical) control groups, a warning will now be emitted. The behavior of those controllers in that situation might change in the future; see this article for more information.

• The Generic Routing Encapsulation (GRE) tunneling protocol is now supported over IPv6. Network address translation (NAT) is also now available for IPv6.

• Server-side support for the TCP fast open protocol enhancement has been merged.

• The kernel now has support for the VXLAN tunneling protocol. See Documentation/networking/vxlan.txt for more information.

• The IMA integrity appraisal security extension has been merged.

• Subject to a configuration option, the "Yama" security module can be automatically stacked regardless of which security module is the "primary" module.

• A number of changes improving support for trusted platform module (TPM) devices have gone in. There is now support for TPM modules supporting the TCG TIS 1.2 specification and Infineon's I2C 0.20 specification. IBM virtual TPMs are now supported. The "physical presence interface" mechanism is also supported, making TPM administration easier.

• New hardware support includes:
  • Boards and processors: Broadcom BCM2835 SoCs, Raspberry Pi boards, and Micrel KS8695 SoC-based boards.

  • Block: s/390 "storage class memory" devices, Calxeda Highbank SATA controllers, and QLogic ISP83xx iSCSI host adapters.

  • Input: Sony PS3 BD remote controls.

  • Miscellaneous: Fairchild FAN53555 regulators, Maxim 8907 voltage regulators, Freescale i.MX28 LRADC analog to digital converters (ADCs), Analog Devices AD7787, AD7788, AD7789, AD7790 and AD7791 SPI ADCs, Analog Devices AD5755/AD5755-1/AD5757/AD5735/AD5737 ADCs, TI LP8788 ADCs, Maxim MAX197 ADCs, Analog Devices ADT7410 temperature monitoring chips, Samsung GPIO/pinmux controllers, Nomadik DB8540 pin controllers, Freescale IMX35 pin controllers, Avionic Design N-bit GPIO expanders, Broadcom BCM2835 GPIO units, Freescale MXS SPI controllers, and NXP SC18IS602/603 SPI controllers.

  • Networking: Silicom Bypass network interface cards, Freescale XGMAC MDIO controllers, and Microchip MRF24J40 transceivers.

  • Serial: NXP SCCNXP serial ports, NXP LPC32XX high speed serial ports, Maxim MAX3108 UARTs, and Digi Realport remote serial devices.

  • USB: Broadcom BCM63xx peripheral controllers, Marvell USB 3.0 PHY controllers, ZTE USB to serial devices, and Cambridge Electronic Design 1401 USB devices (described as "whatever that is" in the Kconfig entry).

Changes visible to kernel developers include:

• The regulator subsystem now supports a "bypass mode" wherein the input is connected directly to the output.

• The handling of read-copy-update grace periods has been pushed into a set of kernel threads, allowing for better preemptability and reduced power consumption; The October 11 LWN Weekly Edition will include an article on this work. RCU has also seen work to allow user-mode execution to be seen as a sort of quiescent state; this is a necessary precondition to fully tickless execution.

• There is a new "parking" facility for kernel threads. The primary purpose is to provide a lightweight mechanism to get these threads out of the way when CPU hotplug events are processed.

• The new TIMER_IRQSAFE timer flag causes the timer function to be executed with interrupts off. It exists to make it possible to safely wait for (and cancel) timers from within interrupt handlers.

• There is a new sensor framework for human input devices; it registers a multifunction device for each sensor hub and enumerates the sensors found attached to it. See Documentation/hid/hid-sensor.txt for details.

• The firmware caching API has been merged. This subsystem will pull copies of potentially interesting device firmware into memory just prior to a system suspend, thus ensuring that the firmware will be available at resume time.

• The feature-removal.txt file is now a removed feature. Linus zapped it, saying: "There is never any reason to add stuff to this idiotic file. Either something isn't getting used, and you should just remove it, or there is no excuse for removing it in the first place. Just stop the idiocy."

• Initial multiplatform support for the ARM architecture has been merged. This is an important step toward the "single zImage" goal, where one kernel can run on a wide variety of ARM systems, but there is still a lot of work to be done before that goal can be reached.

• The non-reentrant workqueues patch has been merged. There are also new mod_delayed_work() and mod_delayed_work_on() functions to modify the expiration time for delayed work items.

• The user namespace conversion work continues, meaning that the newish kuid_t and kgid_t types are appearing in more kernel subsystems.

The 3.7 merge window can be expected to stay open until approximately October 14. That said, Linus has warned the community that he will be traveling during this time; he, along with your editor, will be at the Linux Foundation's Korea Linux Forum. If the travel interferes with the merging process — which hasn't been a problem in previous merge windows — this merge window may be extended to compensate.

Index entries for this article
Kernel	Releases/3.7

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