Kernel Log: Coming in 2.6.36 (Part 1) - Graphics
by Thorsten Leemhuis
Various changes improve the performance and functionality of drivers for graphics chips in the latest Intel mobile processors. Nouveau now supports the Fermi chips used on recent GeForce graphics cards. The Radeon driver in 2.6.36 adds support for underscan, HyperZ and tiling. Extensions for the KDB debugger and Intel's KMS driver allow new debugging functionality.
After releasing the third RC of Linux 2.6.36 at the end of August nothing has happened in the main development tree of Linux for eight days, as Torvalds had visited LinuxCon Brazil 2010. Since Tuesday the tree is moving again; the fourth RC should show up for the start of next work week if Linus Torvalds sticks to his usual work patterns.
The current developer version of 2.6.36 already closely resembles the final version, as kernel hackers have, as ever, used the merge window which opens the development cycle to merge all major changes into the main development tree. The current stabilisation phase is reserved primarily for bug-fix changes rather than major enhancements, as the latter tend to introduce further bugs. Torvalds stuck to this approach more strictly in 2.6.35 and is taking a similar line in 2.6.36, the approach having proved its worth.
The Kernel Log thus can now already offer a comprehensive overview of the major changes in the new kernel version scheduled for release in late October. To keep the material palatable, Kernel Log will, as ever, divide this information up into a series of articles which will look at different areas of the kernel. The 'Coming in 2.6.36' series kicks off below with a description of changes in the area of graphics hardware support. Articles on network support, storage hardware, file systems, architecture code, drivers and other areas will be published over the next few weeks.
Having missed the boat in kernel 2.6.35, kernel hackers have now merged the platform subsystem's intelligent power sharing (IPS) driver into 2.6.36. This allows graphics chips in some Intel Westmere mobile processors (e.g. the Core i5) to increase their clock speed when the processor package is not utilising its full thermal budget. Intel calls this technology, which is aimed at improving 3D performance and likely to find its way into desktop processors at some point in the future, "HD Graphics Dynamic Frequency Technology" and details it in a white paper on the subject.
Intel's KMS driver for its Core i-series mobile processor graphics cores now support frame buffer compression, which, according to the commit comment, reduces power consumption on an unspecified HP laptop by 0.2 watts. The developers have also improved support for embedded DisplayPort (eDP).