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Virtualisation, Tracing, and Debugging

The most important KVM virtualisation advancements are mentioned in Avi Kivity's Git-Pull request: a PPC64 port, improvements to the timer code, lots of work to the emulator code, and features that allow KVM guest systems to be analysed from the host via "perf". The developers made tons of further changes to the tracing and performance monitoring infrastructures to add support, for instance, for the monitoring functions offered in older Pentium 4 CPUs (1, 2) and for Intel's "Precise Event Based Sampling" (PEBS), which allows the retrieval of information about individual memory sectors. New text-based user interfaces for "perf report" (for instance 1, 2) and "perf annotate" (for instance 1, 2, 3, 4) are designed to simplify analysing the collected data.

After several attempts, the Kdb kernel debugger has now been added to the kernel (1, 2, documentation). Its code is based on version 4.4 of SGI's Kdb, and its functionality is slightly different from that of the kgdb debugging feature integrated in the kernel quite a while ago. Kgdb requires a second system and its code was merged with the Kdb code in various places. Further details about Kdb are to be found in an article on, in the documentation provided by the developer at, and in the two Git-Pull requests (1, 2).

Downloading the Linux kernel

New versions of Linux can be obtained from the servers; the contents of these servers are also mirrored on numerous mirrors internationally. However, Linux users who are not familiar with the details of the kernel and its environment should generally not install new Linux drivers and kernels themselves but use the kernels provided by the Linux distributors instead.


The ALSA project's sound drivers for the kernel 2.6.35 have been updated to the level of ALSA version 1.0.23. New too is the snd-asihpi driver for ASI sound cards from AudioScience. There have also been major changes to the code that supports USB audio – a number of them from the support implemented in 2.6.34 for version  2.0 of the USB audio specification (such as 1, 2, 3, 4, 5, 6).

A new "Remote Controller Subsystem" mainly produced by V4L / DVB maintainer Mauro Carvalho Chehab is intended to pave the way for better support of infra-red controls (such as 1, 2, 3, 4, 5). Up to now, most distributions have provided Lirc for this purpose, but it unfortunately it does not fulfil the quality requirements of kernel developers and may someday work with the new subsystem in a different form.

An article from last December sheds light on the situation.

Next: In brief, Statistics for 2.6.35

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