What came in through the merge window

As of this writing, the 2.6.21 merge window is wide open. Something over 2,300 changesets have been merged, making changes all over the tree. This article summarizes the major changes merged so far for the 2.6.21 release.

User-visible changes include:

• A big ACPI update with sysfs support for backlight devices, a simplified table manager which adds more functionality with less code, the removal of 16-bit support, experimental support for removable drive bays, and more.

• New device drivers add support for Silan SC92031 network interface chips, Qlogic 4032 NIC chips, PA Semi PWRficient Ethernet chips, Avocent PC300/RSV and PC300/X21 WAN cards, Atmel MACB network controllers, Yukon Extreme Ethernet chips, several USB-attached NCR printers, Chelsio T3 10G Ethernet adapters, GTCO CalComp tablets, Delkin compact flash adapters, Attansic L1 Gigabit Ethernet adapters, VIA VT1708(a) HD audio codecs, several auxilliary LCD display devices, PC-style CMOS real-time clocks, SNI RM 53c710 SCSI controllers, Gigaset M101 wireless RS232 adapters, and S3 Trio/Virge video chips (fbdev). Also, the long-broken SKMC and Oaknet drivers have been removed.

• Sysfs shadow directory support - allowing different namespaces to have different views of sysfs - has been added.

• USBmon has a new binary API which promises to be somewhat faster and more complete than the older, text-based interface.

• A big PowerPC/Cell/PS3 update, including support for the Toshiba "Celleb" architecture, serial ports accessed through OpenFirmware, and AMCC Taishan 440GX evaluation boards.

• Netfilter now has a connection tracking helper for the SANE network scanner protocol.

• Encryption modules for the FCrypt and Camilla cipher algorithms have been added.

• The ASoC (ALSA System on Chip) layer has been added to the ALSA sound system. It provides improved support for sound processors on embedded systems; it includes a dynamic power management subsystem. A number of platform and codec drivers for ASoC have been merged as well.

• Tainting the kernel from user space is now supported.

• Minix V3 filesystems can now be mounted on Linux systems.

• eCryptfs now has public-key encryption support.

• A long set of patches has made the kernel able to support boot-time command lines of arbitrary length.

Changes visible to kernel developers include:

• Quite a few kobject functions - kobject_init(), kobject_del(), kobject_unregister(), kset_register(), kset_unregister(), subsystem_register(), subsystem_unregister(), and subsys_create_file() - now return harmlessly if passed a NULL pointer.

• Many kernel subsystems which once used class_device structures have been changed to use struct device instead; this work is toward a long-term goal of getting rid of the class tree and having a single device tree in sysfs.

• Significant changes have been made to the crypto support interface.

• The device resource management patches, making a lot of driver code easier to write, have been merged.

• The DMA memory zone (ZONE_DMA) is now optional and may not be present in all kernels.

• The local_t type has been made consistent across architectures and has gained some documentation.

• The nopfn() address space operation can now return NOPFN_REFAULT to indicate that the faulting instruction should be re-executed.

• A new function, vm_insert_pfn(), enables the insertion of a new page into a process's address space by page-frame number.

• A new driver API for general-purpose I/O signals has been added.

• The sysctl code has been heavily reworked, leading to a number of internal API changes.

A number of patches are still waiting to merged, and some decisions are yet to be made. Come back next week for what should be the final list of major new features in 2.6.21.

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