KERNEL NEWS ZACK’S KERNEL NEWS New PowerTOP Tool for Some Removal Tracking Battery Usage of Old Code Arjan van de Ven from Intel announced Adrian Bunk and the new PowerTOP tool. PowerTOP ana- Wim Van Sebroeck lyzes everything running on a system have posted a patch and reports on how power is being con- to remove the i8xx_ sumed. With this tool, it’s possible to tco watchdog driver. identify a lot of ways to save power on The driver had been a laptop. Intel’s testing showed ways of scheduled to be taken improving a “typical” laptop’s battery out in 2.6.22, and its life by more than an hour. Regardless of functionality had al- those particular tests, it does seem clear ready been replaced that a tool like this will be extremely by the iTCO_wdt useful, both for regular users and for the watchdog driver. maintainers of tools that might inadver- tently use too much power. Open Source New 965GM software everywhere can now look Express forward to receiving patches to lower Chipset Driver power consumption. I imagine that Keith Packard of Intel whether you run PowerTOP or not, your announced a new laptop will start to run longer as soft- 965GM Express Chip- Figure 1: Save power on a laptop with PowerTOP. ware is updated based on this new data. set driver produced by http:// www. linuxpowertop. org that company. As he put it, this chipset it seems like it would be good to avoid “represents the first mobile product that doing all that work in the first place. implements fourth-generation Intel Which leads back to the idea of updating The Linux kernel graphics architecture. Designed to sup- the feature-removal-schedule.txt file. mailing list com- port advanced rendering features in It’s not clear whether much will come prises the core of modern graphics APIs, this chipset in- of Robert’s information-gathering expe- Linux development cludes support for programmable vertex, dition. Typically, the folks who would geometry, and fragment shaders.” A be affected by a particular code removal activities. Traffic vol- bunch of folks were happy to hear this won’t notice the debate until someone umes are immense, news, and Jeff Garzik said, “Here’s hop- actually tries to remove it, at which often reaching ten ing that Intel produces a standalone point they’d squawk loudly. It may be thousand messages video card eventually, to further take that Robert’s attempt to find a consensus in a given week, and away market share from closed source beforehand is just not workable. keeping up to date competitors.” with the entire scope of development The Raw Driver Remains is a virtually impossible task for one When to Remove Old Code The raw driver has been taken off the list person. One of the few brave souls to Robert P. J. Day started an effort to up- of deprecated kernel features to be re- take on this task is Zack Brown. date the Documentation/ feature-removal- moved from the code at some future Our regular monthly column keeps schedule.txt file, so the features sched- date. Dave Jones has noted that after re- you abreast of the latest discussions uled for removal would correspond with peated attempts to get rid of this driver, and decisions, selected and summa- the features that should be scheduled for it still had a significant user base that rized by Zack. Zack has been publish- removal. Everyone agrees the file is didn’t seem to be going away any time ing a weekly online digest, the Kernel woefully out of date, but the best way soon. He posted a patch to take the raw Traffic newsletter, for more than five to update it is not clear. One way, as sug- driver off the to-be-removed list and also years now. Even reading Kernel Traffic gested by Stefan Richter, is just to try to to change its status in the configuration alone can be a time-consuming task. remove the scheduled code and then see system to no longer be deprecated. Linux Magazine now provides you if anyone complains. The problem with This last change drew some criticism. with the quintessence of Linux Kernel this approach is that it’s a bit of work to Some folks pointed out that the feature activities, straight from the horse’s remove code, and if the only result is should still be listed as deprecated, to mouth. that the date of removal is rescheduled, prevent it from getting any new users. 14 ISSUE 81 AUGUST 2007 KERNEL NEWS The problem with this, as Dave pointed ing boards, and he (Khasim) would add Linux sometime in 2007. But Christoph out, is that leaving it deprecated would support for new boards. Russell King also pointed out that hardware becomes only prompt other kernel folks to think volunteered to maintain the mmci.c file a significant limiting factor with such that it had been inadvertently left out of as well. high CPU counts, and a good filesystem the to-be-removed list. (he recommended XFS) would also be Those folks would then submit Subsystem and Intel I/ OAT essential. patches to add it back in, and we’d have DMA Maintainership a circle. Chris Leech has posted some patches Purging the Kernel of listing himself as the official maintainer UMSDOS Status of MMC Drivers of the DMA Generic Memcopy Subsys- Once a valiant entryway into the Linux Pierre Ossman said he was going to post tem and the Intel I/ OAT DMA Driver. world, UMSDOS has been gone since a patch listing some MMC drivers as or- There doesn’t seem to be any problem 2.6.11. Or, UMSDOS has been almost phaned unless maintainers stepped for- with this, except David S. Miller wants gone. Jesper Juhl has recently posted ward to take responsibility for them. Chris to submit his patches to the netdev patches to remove a few remaining con- These drivers included the AMD mailing list, since a lot of his work fig options and file references. The only AU1XX0 MMC, the ARM Primecell touches the TCP code. things now remaining of UMSDOS are MMCI PL180/ 1, the ATMEL AT91 MCI, the entries in the CREDITS file and the the Motorola I.MX MMCI, the PXA DMA Generic Memcopy ioctl numbers UMSDOS used. MMCI, and the TI OMAP MMC Interface Linux Kernel Scalability? Originally, Jesper’s patch removed drivers. Pavel Pisa volunteered to main- Rajib Majumder recently asked whether the ioctls as well, but this raised some tain the Motorola I.MX MMCI driver and Linux was able to scale up to 8 CPUs alarms with H. Peter Anvin, because submitted a patch listing himself as the nowadays. Tony luck pointed out that ioctls should not be reused by other official maintainer. systems with 512 and 1024 CPUs were code, even if they go defunct. Khasim Syed Mohammed said that already in production use, and a 4096- Jesper’s later version of the patch Carlos Aguiar and Anderson Briglia CPU system had been built as a proto- documented all of UMSDOS’s removed would be interested in maintaining the type. Christoph Lameter predicted we’d ioctls so no one would mistakenly use TI OMAP MMC Interface driver for exist- be seeing a 16384-CPU system running the same numbers. Advertisement.