2.6.30 merge window, part I

• The relatime mount option is now the default; this means that file access times will only be updated if they are newer than the creation or modification times. Another change merged also causes the access time to be updated at least once per day. Users needing access times to be updated for every access can use the new "strictatime" mount option to get that behavior. See That massive filesystem thread for more information on this change.

• At long last, the integrity management patches have been merged. Among other things, this code can use the trusted platform module (TPM) to ensure that the files on a system have not been tampered with and to do remote attestation.

• Also at long last, TOMOYO Linux has been merged. TOMOYO is a pathname-based security module similar to (but significantly different from) AppArmor.

• There is a new cpuinfo_transition_latency sysfs variable for CPU frequency governors; it serves to inform user space of the time it takes for the CPU to transition from one frequency to another.

• There is now support for the new AES-NI cryptographic instructions being introduced into Intel processors; see this white paper [PDF] for details on AES-NI.

• The x86_64 and SuperH architectures have gained kexec jump support.

• There is a new guest debugging interface for KVM, allowing the host to do interactive debugging of guest systems. KVM has also gained support for PowerPC e500 processors.

• There is a new user-space API for detailed control over the timestamping of network packets. See Documentation/networking/timestamping.txt for details.

• The Reliable Datagram Sockets (RDS) protocol is now supported by the networking layer. See Documentation/networking/rds.txt for more information.

• The x86 architecture now has an option to put a "canary" value at the end of the kernel stack; if that value ever changes, the stack has been (accidentally or maliciously) overrun.

• The reiserfs filesystem has seen a burst of work which cleans up the code, improves SELinux support, and improves performance. This is likely to be the last set of updates for reiserfs.

• The usual array of new drivers has been merged. They include:
  • Block: PCI-Express SAS 6Gb/s host adapters.

  • Graphics: AMD R6xx/R7xx GPUs (2D only for now).

  • Networking: USB Qualcomm Serial modems, Marvell Libertas 8686 SPI 802.11b/g cards, Marvell 88w8xxx TOPDOG PCI/PCIe wireless cards, Prism54 SPI (stlc45xx) wireless adapters, Atmel at76c503/at76c505/at76c505a USB wireless adapters, OpenCores 10/100 Mbps Ethernet MAC devices, and Atheros "otus" 802.11n USB devices.

  • Sound: Mitac MIO A701 phones, Wolfson Micro WM8400 and WM9705 codecs, Wolfson Microelectronics 1133-EV1 modules, Atmel Audio Bitstream DAC devices, Atmel AC97 controllers, Asaki-Kasei AK4104 S/PDIF transmitters, Echo Audio IndigoIOx and IndigoDJx cards, Turtle Beach Classic, Fiji and Pinnacle cards, and Asus Xonar Essence STX sound cards.

  • Video/DVB: Mars-Semi MR97310A USB cameras, Freescale MC44S803 low power CMOS broadband tuners, SQ Technologies SQ905-based USB cameras, i.MX3x camera sensor interfaces, ST STV0900 satellite demodulators, ST STV6110 silicon tuners, SQ Technologies SQ905C-based USB cameras Zarlink ZL10036 silicon tuners, LG Electronics LGDT3305-based tuners, Hauppauge HD PVR USB devices, and Intel CE6230 DVB-T USB2.0 receivers.

  • Processors and systems: SuperH SH7786, ESPT-Giga SH7763-based reference boards, SMSC reference platform with a SH7709S CPUs, Palm LifeDrive and Tungsten|T5 systems, Brivo Systems LLC ACS-5000 master boards, Dave/DENX QongEVB-LITE platforms, Marvell RD-78x00-mASA development boards, Marvell PXA168 and PXA910 processors, TI OMAP850 processors, OMAP 3430 SDP boards, Nokia RX-51 internet tablets, Teltonika 3G Router RUT100 systems, Faraday FA526 cores, Cortina Systems Gemini family SoCs, GE Fanuc SBC310 and PPC9A PowerPC boards, Freescale Media5200 boards, AMCC Redwood(460SX) systems, Phytec phyCORE-MPC5200B-IO (pcm032) boards, and Freescale MPC8544 ("Socrates") boards.

  • Miscellaneous: AMCC PPC4xx crypto accelerators, Adrienne Electronics Corporation PCI time code devices, Symbol 6608 barcode scanners, E-Ink Broadsheet/Epson S1D13521 controllers, NXP Semiconductor PCA9665 i2c controllers, and Siemens Syleus and Hades sensor chips.

• The "Phidgets" USB drivers have been removed; users should shift to the user-space drivers instead.

Changes visible to kernel developers include:

• The adaptive spinning mutex patch has been merged. This change will cause mutexes to behave more like spinlocks in the contended case. If (and only if) the lock is held by code running on a different CPU, the mutex code will spin on the assumption that the lock will be released soon. This behavior results in significant performance improvements. Btrfs, which had its own spinning mutex implementation, has been converted to the new mutexes.

• There is a new set of functions added to the crypto API which allow for piecewise compression and decompression of data.

• The bus_id member of struct device is gone; code needing that information should use the dev_name() macro instead.

• There is a new timer function:

      int mod_timer_pending(struct timer_list *timer, unsigned long expires);
  

  It is like mod_timer() with the exception that it will not reactivate an already-expired timer.

• There have been some changes around the fasync() function in struct file_operations. This function is now responsible for maintaining the FASYNC bit in struct file; it is also now called without the big kernel lock held. Finally, a positive return value from fasync() is mapped to zero, meaning that the return value from fasync_helper() can be returned directly by fasync(). (This is your editor's modest contribution to 2.6.30).

• The SCSI layer has a new support library for object storage device support; see Documentation/scsi/osd.txt for details.

• The x86 "subarchitecture" mechanism has been removed, now that no architectures actually use it. The Voyager architecture has been removed as a result of these changes.

• x86 is also the first architecture to use a new per-CPU memory allocator merged for 2.6.30. This allocator changes little at the API level, but it will provide for more efficient and flexible per-CPU variable management.

• Support for compressing the kernel with the bzip2 or lzma algorithms has been added. Support for the old zImage format has been removed.

• The asynchronous function call infrastructure is now enabled by default.

• The DMA operations debugging facility has been merged.

• The owner field of struct proc_dir_entry has been removed, causing lots of changes throughout the tree.

If the usual two-week pattern holds, the merge window can be expected to remain open through about April 9. The rate at which changes flow into the mainline will likely be lower for the second half of the merge window - the alternative is for this development cycle to be far larger than any of its predecessors. But it is certain that more interesting changes will be merged for 2.6.30.

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