and closed the 2.6.29 merge window on January 10.
A little over 2000 changesets were merged after the writing of last week's merge window
; this article completes the summary for this development
Before getting into the details, though, it is worth pointing out that the
2.6.29-rc1 kernel has a couple of unusual traps for developers and
testers. If you are playing with this kernel, you should be aware of the
So what else was merged for 2.6.29? User-visible changes include:
- At the top of the list, of course, is the merge of the Btrfs
filesystem. It cannot be repeated too many times, though, that Btrfs
is still a development filesystem. Things are changing
quickly, and it still will panic the system if you run out of space.
Now is a good time for people to play with Btrfs - especially those
who are willing to report bugs or submit enhancements. But it is not,
yet, time to entrust your Valuable Intellectual Property to this
- Also merged was the squashfs compressed,
read-only filesystem. Squashfs has been packaged by distributors for
years; its merger into the mainline was certainly overdue.
- There is now kernel support for WiMAX networking. The current code
supports Intel's Wireless Wimax Connection 2400m devices, but others
are expected for the future. See this
documentation file for a bit of information on the WiMAX stack.
- There are new drivers for Atmel AVR32-based Hammerhead boards,
Linear Technology LTC4245 Multiple Supply Hot Swap Controller I2C
Oxford OXU210HP USB host/OTG/device controllers,
MIPS CI13412 USB controllers,
Freescale IMX USB peripheral controllers,
TI TWL4030 USB transceivers,
Dell-specific laptop backlight and rfkill devices,
ALIX.2 and ALIX.3 series LED controllers,
PIKA FPGA watchdog devices,
GE Fanuc watchdog timers, and
NXP PCF50633 multifunction chips (as seen in OpenMoko devices).
- The Blackfin architecture has gained symmetric multiprocessing
support. Also added is support for the BF51x family of processors.
- The memory controller has been extended to control swap usage as
well. Previously, it would be possible for a memory-controlled group
to exhaust swap space.
- The new "xenfs" virtual filesystem allows for information sharing and
control between Xen domains, the hypervisor, and the host system.
- It is now possible to create and run ext4 filesystems without a
journal. One loses the benefits of journaling, obviously, but there
is a notable increase in performance.
- The filesystem freeze
feature, allowing a suitably-privileged user to suspend changes to a
filesystem (for backup purposes, perhaps) has been merged.
Changes visible to kernel developers include:
- The exclusive I/O memory
allocation functions have been merged.
- The exports for a number of SUNRPC functions have been changed to
- The internal MTD (memory technology device) API has seen significant
changes aimed at supporting larger devices (those requiring 64-bit
- An infrastructure for
asynchronous function calls has been merged. This code is still a
work in progress, though, and, for 2.6.29, it will not be activated in
the absence of the fastboot command-line parameter.
And that completes the set of major changes added for 2.6.29 - with one
possible exception. Linus has indicated
that he would be willing to slip in an updated version of the spinning
mutex code (as described in this
Btrfs article) if it passes review in the near future.
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