2.6.32 merge window, part 2

Changes visible to users include:

• There are two new system clocks available: CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE. They are aimed at applications which need to obtain timestamps with a minimal cost, and are willing to lose some resolution in the process.

• The Sunplus S+core architecture is now supported.

• The performance monitoring code has gained new capabilities for recording and analyzing scheduler latency information. There is a new facility for tracking power management state change events. There has also been a rebranding from "performance counters" to "performance events".

• Arjan van de Ven's timechart tool has been merged. Timechart records system events in a way which allows users to zoom in on specific periods of time and gain increasing levels of detail on where system delays are coming from.

• The Intel i915 graphics driver now supports dynamic clock frequency control. This feature allows clock frequencies to be reduced when there is little or no graphics activity with a corresponding reduction in power use.

• The Radeon kernel mode setting (KMS) code continues to evolve at a rapid rate, with increasing numbers of features being supported there. There is now KMS support for the R600 series.

• Quite a bit of new information has been added to virtual files like /proc/meminfo with the intent of helping administrators track down memory users in out-of-memory situations.

• The kernel shared memory (KSM) subsystem has been merged. KSM scans memory for pages with identical content. Duplicate pages are replaced with copy-on-write links, resulting in significant reductions in memory use.

• The cpuidle governor changes described in this article have been merged.

• The Video4Linux layer now understands the ISDB-T and ISDB-S broadcast standards, giving access to digital TV in places like Japan and Brazil.

• Expanded information about thread stack usage can now be found under /proc.

• The ocfs2 filesystem has gained reflink support, but without the (to be reworked) reflink() system call.

• Write support has been removed from the qnx4 filesystem; that is likely to inconvenience very few users, since it never really worked anyway.

• There is the usual pile of new drivers:
  • Boards and processors: Broadcom BCM63xx system-on-chip processors, TI DA830/OMAP-L137 and DA850/OMAP-L138 SOC processors, EcoVec (SH7724) SuperH boards, and SuperH SH7757 processors.

  • Graphics: VIA VX855 integrated graphics chipsets, DA8xx/OMAP-L1xx framebuffers, Gumstix Overo LCD controllers, OMAP3 EVM LCD controllers, and Qualcomm MSM/QSD framebuffers.

  • Block: ARTOP 867X 64bit 4-channel UDMA133 ATA controllers.

  • USB: Nuvoton W90X900(W90P910) EHCI controllers and Philips ISP1362 host controllers.

  • Video4Linux: Conexant 25821-based TV cards DiBcom DiB8000 ISDB-T/ISDB-Tsb demodulators, GL860 USB camera devices, NXP SAA7164-based TV cards, Friio ISDB-T USB2.0 receivers, and Earthsoft PT1 PCI cards.

  • Miscellaneous: Texas Instruments TMP421/422/423 temperature sensors, GPIO devices on a number of Freescale Coldfire CPUs, Wolfson Microelectronics WM831x power management ICs, Motorola PCAP touchscreens, ST-Ericsson AB3100 RTC devices, Renesas R8A66597 USB Peripheral Controllers, Nuvoton NUC900 series watchdog devices, Winbond IR remote control devices, Qualcomm MSM 7X00A SDCC controllers, OMAP4 multimedia card interfaces, PPC4xx SPI controllers, Freescale STMP37xx/378x SPI/SSP controllers, Freescale MC33880 high-side/low-side switches, ST-Ericsson COH 901 331 realtime clocks, Philips PCF2123 RTC devices, Freescale STMP3xxx and MXC RTC devices, ACPI 4.0 power meters, and TI TPS65023 and TPS6507x voltage regulator devices.

Changes visible to kernel developers include:

• The x86 architecture code has been significantly reorganized so that support for the Intel "Moorestown" architecture could be added.

• The driver core API has been extended to allow subsystems to provide non-default permissions for device nodes created in devtmpfs.

• The (now) unused kernel markers mechanism has been removed; tracepoints should be used instead.

• The user-space USB driver API now allows drivers to claim specific hub ports.

• There are new tracepoints for memory page allocation and freeing events and timer (and hrtimer) events.

The merge window would normally be nearing its end; it's possible that Linus will extend it slightly, though, to make up for the time he has spent at LinuxCon and the Linux Plumbers conference.