3.17 merge window part 1

• The perf tool can now perform page fault tracing and generate associated statistics. Additionally, "perf timechart" can generate charts displaying I/O events.

• Four-level page tables have been added to the arm64 architecture, greatly expanding the amount of virtual memory that can be addressed. This feature will likely not be enabled in 3.17 kernels, though, due to the need for more work. The arm64 architecture has also gained audit support.

• The cryptographic subsystem has gained support for the NIST-specified SP800-90A deterministic random bit generator. There is also support for parsing PKCS#7 signed-data messages and verifying the signatures.

• The netfilter "ulog" target, long deprecated, has finally been removed. The "NFLOG" target should be used instead.

• Cross-thread filter setting for the secure computing ("seccomp") facility has been added. The interface has changed over time, though; there is now a new system call for seccomp:

      int seccomp(unsigned int operation, unsigned int flag, const char *args);
  

  This man page describes the new system call and the available commands.

• The security module subsystem has gained a new hook (kernel_fw_from_file()) that may be used to verify the integrity of firmware blobs before accepting them in the kernel.

• The getrandom() system call has been merged.

• New hardware support includes:
  • Block: NVIDIA Tegra124 AHCI SATA controllers, Qualcomm APQ8064 and IPQ806x SATA SerDes/PHY controllers, Marvell Berlin SATA PHY controllers, and STMicroelectronics MIPHY365X SATA PHY controllers.

  • Clock: TI Palmas clk32kg and clk32kgaudio clocks, Rockchip rk3188, rk3066, and rk3288 clocks, Qualcomm APQ8084 clock controllers, and Cirrus Logic CLPS711X clocks.

  • Hardware monitoring: Lattice POWR1220AT8 power-management ICs, Texas Instruments TMP103 temperature sensors, Texas Instruments TPS40422 power management chips, IBM POWERNV platform sensors, and PWM-connected fans.

  • IIO: EPCOS T5403 digital barometric pressure sensors, Kionix KXCJK-1013 triaxial acceleration sensors, Asahi Kasei AK09911 3-axis compasses, Microchip MCP4902, MCP4912, and MCP4922 digital-to-analog converters, Maxim max1027, max1029 and max1031 analog-to-digital converters, Intersil ISL29125 digital color light sensors, TAOS TCS3414 digital color sensors, and Honeywell HMC5983 3-Axis magnetometers.

  • Miscellaneous: Intel E3-1200 DRAM controllers, Intel DH895xcc crypto accelerators (and Intel "Quick Assist Technology" devices in general), Intel MIC X100 DMA controllers, Qualcomm crypto engine accelerators, Thunderbolt devices on Apple systems, Maxim DS2406 addressable switches, Rockchip SPI controllers, Dialog Semiconductor DA9211/DA9212 regulators, and Atmel AT91 interrupt controllers.

  • Networking: TI CC2520 802.15.4 wireless-PAN networking controllers, Marvell Armada 375 Ethernet controllers, and STMicroelectronics ST21NFCB NFC controllers.

  • USB: Silicon Mitus SM5502 USB port switches, Emma Mobile EMXX USB function device controllers, Renesas R-Car xHCI host controllers, and NetChip PLX USB3380 and USB3382 USB peripheral controllers.

  • Video4Linux: Allwinner sunXi IR controllers, AirSpy software-defined radio controllers, Silicon Labs SI2165 DVB-C/-T demodulators, and Samsung Exynos3250 JPEG codecs.

  It's worth noting that 14 unloved drivers were removed from the staging tree, eliminating some 250,000 lines of code. Indeed, as of this writing, 3.17 is actually smaller than 3.16. A kernel release has been smaller than its predecessor only one other time in kernel development history (2.6.36).

Changes visible to kernel developers include:

• A number of changes have been made to the timekeeping core in order to make it ready for the year 2038; see this article for details.

• The dma-buf fence API has been added. This subsystem enables cross-device synchronization and coordination, especially around the use of DMA buffers. In the end, this API was made available to all kernel modules; a push to change it to the EXPORT_SYMBOL_GPL() mechanism was not successful.

• The "config-bisect" mode in the ktest utility has been reworked to be much smarter about finding the actual configuration change that causes problems.

• The ftrace subsystem has been reworked to make things more efficient when multiple tracers are active, and, in particular, when function graph tracing is being performed.

• Arm64 kernels can now be built with the -fstack-protector option to detect stack corruption.

• The wait_on_bit() function (along with its variants) has been reworked to no longer require an "action" function since, as it turned out, most of those functions were duplicates of each other.

In the 3.16 announcement, Linus noted that he will be traveling during the latter part of the 3.17 merge window. That may, he said, cause this merge window to be a little longer than usual. Subsystem maintainers would be wise to not count on that when sending their pull requests, though. It seems likely that Linus will feel motivated to close the merge window and get the 3.17-rc1 release out before the Kernel Summit starts on August 18.