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Kernel Traffic #297 For 19 Feb 2005

By Zack Brown

Table Of Contents

Mailing List Stats For This Week

We looked at 1869 posts in 11MB. See the Full Statistics.

There were 616 different contributors. 252 posted more than once. The average length of each message was 99 lines.

The top posters of the week were: The top subjects of the week were:
91 posts in 623KB by Adrian Bunk
47 posts in 159KB by Greg KH
40 posts in 159KB by Vojtech Pavlik
38 posts in 199KB by Matt Mackall
36 posts in 221KB by Evgeniy Polyakov
70 posts in 332KB for "User space out of memory approach"
62 posts in 396KB for "2.6.11-rc2-mm1"
56 posts in 316KB for "Memory leak in 2.6.11-rc1?"
44 posts in 217KB for "thoughts on kernel security issues"
41 posts in 195KB for "2.6.11-rc2-mm1: SuperIO scx200 breakage"

These stats generated by mboxstats version 2.2

1. User-Space OOM Killer

10 Jan 2005 - 28 Jan 2005 (70 posts) Archive Link: "User space out of memory approach"

Topics: OOM Killer

People: Mauricio LinMarcelo TosattiEdjard Souza Mota

Mauricio Lin said, "We have done a comparison between the kernel version and user space version and apparently the behavior is similar. You can also get this patch and module to test it and compare with kernel OOM Killer. Here goes a patch and a module that moves the kernel space OOM Killer algorithm to user space. Let us know about your ideas." Marcelo Tosatti found the idea interesting, though he had no specific comments on the code itself. He did say, "The userspace OOM killer is dangerous though. You have to guarantee that allocations will NOT happen until the OOM killer is executed and the killed process is dead and has its pages freed - allocations under OOM can cause deadlocks. "OOM-killer-in-userspace" is unreliable, not sure if its worth the effort making it reliable (mlock it, flagged as PF_MEMALLOC, etc)." But he replied to himself, "Actually its only unreliable if its called from OOM time. The case here is you have a daemon which periodically writes to /proc/oom?" Mauricio replied, "Yes, let me explain the idea. When the memory consumption reaches a percentage of usage, as 98% or something like that, we call this as red zone. So when red zone is reached, the ranking algorithm is started to select which processes could be killed whe out of memory happens. If the memory comsumption is less than this percentage (not in red zone), the ranking algorithm is not executed. So we have a loop the check the memory comsumption all the time and if the red zone is reached, the ranking algorithm is started before the system get the out of memory state."

Edjard Souza Mota also pointed out that this patch only moved the OOM killer's ranking algorithm to user-space, not the killer itself. He said, "In that sense the approach is different and might be worth testing, mainly for cases where we want to allow better policies of ranking. For example, an embedded device with few resources and important different running applications: whic one is the best? To my understanding the current ranking policy does not necessarily chooses the best one to be killed." This made more sense to Marcelo, and he felt the patch was more worth considering in this case. Folks continued discussing the technical details for awhile, with no real consensus on what the best solution would be.

2. Linux 2.6.11-rc2 Released

21 Jan 2005 - 27 Jan 2005 (26 posts) Archive Link: "Linux 2.6.11-rc2"

Topics: Kernel Release Announcement

People: Linus TorvaldsSytse WielingaChristoph HellwigUdo A. Steinberg

Linus Torvalds announced Linux 2.6.11-rc2, saying, "Ok, trying to calm things down again for a 2.6.11 release. Tons of small cleanups, annotations and fixes here. Driver updates, cpufreq, ppc, parisc, arm.. Pls check that I got it all." Udo A. Steinberg posted a netfilter compile-time bug, which Martin Josefsson diagnosed and fixed; Udo urged Linus to accept the patch, but Linus replied, "Please go through Davem, he's quite responsive, but prefers things like this to be sent to the netdev mailing list too if it hasn't been there already (netdev@oss.sgi.com)."

Elsewhere, Sytse Wielinga said, "Linus, could you please put skb_copy_datagram back in place? It's not used anymore in the kernel, but the vmnet module (in vmware) still uses this interface to skb_copy_datagram_iovec." He posted a patch, but Christoph Hellwig replied, "Just fix vmware. Or upgrade to a fixed version" .

3. Linux 2.6.11-rc2-mm1 Released

24 Jan 2005 - 27 Jan 2005 (132 posts) Archive Link: "2.6.11-rc2-mm1"

Topics: Kernel Release Announcement, Version Control

People: Andrew MortonBrice GoglinFlorian BohrerDave Jones

Andrew Morton announced Linux 2.6.11-rc2-mm1, saying:

ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.11-rc1/2.6.11-rc2-mm1/

Brice Goglin reported:

X does not work anymore when using DRI on my Compaq Evo N600c (Radeon Mobility M6 LY). My XFree 4.3 (from Debian testing) with DRI uses drm and radeon kernel modules.

Instead of the usual gdm window, I get a black or noisy screen (remaining image parts of last working session). The mouse pointer works. Sysrq works. But Caps-lock doesn't work. The machine pings but I can't ssh.

I don't know exactly what's happening. I don't see anything interesting in dmesg. Removing DRI from Xfree config (even if drm/radeon modules are loaded) makes X work again. Linus' 2.6.11-rc2 works fine.

Florian Bohrer had the same problem, with the NVidia driver. He said it "seems that AGP is totally brocken." Close by, Dave Jones took responsibility for the problem, and asked folks to drop the agpgart-bk update for the moment. A couple of hours he posted a patch, but he added that there were still problems remaining. Brice gave it a try, and reported 100% success. He offered to help with any further tests Dave wanted; and Dave said, "It's quite remarkable that it works at all."

4. Status Of 802.11x Support

25 Jan 2005 - 28 Jan 2005 (3 posts) Archive Link: "Where Linux 802.11x support needs work"

Topics: Bug Tracking, Ioctls

People: Dan WilliamsDave Jones

Dan Williams said:

This list of stuff that should get fixed in Linux wireless grew out of my attempt to put a GUI on top of Linux wireless with NetworkManager (http://people.redhat.com/dcbw/NetworkManager). This isn't, of course, a demand or anything, and I've been personally slowly fixing stuff up as I come to it (orinoco merge, fixing linux-wlan-ng, small kernel wireless driver patches), but I don't think anyone has posted a comprehensive list of where Linux wireless currently falls a bit short.

I think the biggest issue here is that the Wireless Extensions API has stagnated a bit, and driver writers have gone off and done their own thing (for example, WPA support) because the WEAPI hasn't shown leadership in this area. That's fixable, and at this point doesn't seem to be a large amount of work since the main offender here is only WPA.

Second, there are, for historical reasons most likely, areas where the WEAPI has multiple methods of encoding data to/from user space. For example, WE Quality values and WE Frequency/Channel values. Quality is either signed or unsigned 8-bit number, which (I believe) is either a raw dBm/rssi value or a percentage value, respectively. Frequency uses exponent & mantissa notation, OR a channel # stuffed into the exponent/mantissa structure. Things like that.

Comments appreciated, and hopefully this may spark some wider effort to get a few things fixed.

So without further ado, here's the list:

Levels of Importance (my opinion):

  1. All drivers _MUST_ support wireless scanning (*cough* orinoco *cough*)
  2. WPA support needs to be standardized in Wireless Extensions
  3. Consistent (and present) quality data among drivers, both for currently connected AP and for scanned APs
  4. rtnetlink link notification for all drivers when they associate with an AP
  5. Ad-Hoc mode support
  6. Ethtool support
  7. Cisco firmware issues

5. Removing eepro100, xircom_tulip_cb, And iph5526 Drivers

27 Jan 2005 - 1 Feb 2005 (16 posts) Archive Link: "[ANN] removal of certain net drivers coming soon: eepro100, xircom_tulip_cb, iph5526"

Topics: Networking

People: Jeff GarzikChristoph HellwigGreg KH

Jeff Garzik said:

Though this has already been mentioned, I thought I would send out a reminder. The following net drivers are slated for removal "soon", in the next kernel version or so:

  1. iphase (iph5526 a.k.a. drivers/net/fc/*)

    Been broken since 2.3 or 2.4. Only janitors have kept it compiling.

  2. xircom_tulip_cb

    Unmaintained, and does not work for all xircom 32bit cards. xircom_cb, on the other hand, works for ALL xircom 32bit cards.

  3. eepro100

    Unmaintained; users should use e100.

    When I last mentioned eepro100 was going away, I got a few private emails saying complaining about issues not yet taken care of in e100. eepro100 will not be removed until these issues are resolved.

On iphase, Christoph Hellwig pointed out that not even janitors kept it compiling, and in fact that it had been unable compile for over two years.

Greg KH suggested adding all of these projects to the list of deprecated drivers in the Documentation/ directory.

6. usbutils Version 0.70 Released

30 Jan 2005 Archive Link: "ANNOUNCE: usbutils-0.70"

Topics: FS: devfs, Hot-Plugging, Modems, Networking, PCI, USB, Version Control

People: David Brownell

David Brownell said:

WHAT

The "usbutils" package is most useful for the "lsusb" utility, which can provide considerable detail about the USB devices connected to your Linux system. (It's like "pciutils" is for PCI.) When making bug reports, or otherwise troubleshooting, "lsusb -v" output is very useful; often more so than /proc/bus/usb/devices output.

For folk using Linux 2.4 kernels, this also provides "usbmodules" which can help with the "coldplug" problem: setting up devices that are connected before the OS is capable of running all of the necessary "hotplug" programs.

WHY

The last official release was version 0.11 in August 2002. This version should incorporate almost all of the bug fixes and patches that have been floating around since then. If you're using patches that haven't been merged, please resolve that.

This "lsusb" version is aware of USB 2.0 features; the 0.11 version only understood USB 1.1 functionality.

This version understands many more types of descriptors; it previously understood primarily audio and HID descriptors.

Note that if the kernel HID driver is bound to a device, lsusb can't show its descriptors. You can workaround this by removing the "usbhid" module before running lsusb against that device.

This version uses the system's version of "libusb", rather than its own private copy. That involved some API changes. It also accounted for the only loss of functionality: lsusb doesn't currently list the language strings supported by the device. Many devices don't seem to bother with anything beyond English.

WHERE

Download from one of the SourceForge mirrors for the Linux-USB project:

http://sourceforge.net/project/showfiles.php?group_id=3581&package_id=142529

Also, current source is in CVS for the Linux-USB project at SourceForge. If you have any patches (support for CJKV strings?), prepare them against CVS and post them to the linux-usb-devel list.

HOW

It uses GNU autoconf, so configure and build it:

        $ tar xf usbutils-0.70.tar.gz
        $ cd usbutils-0.70
        $ ./configure                   <-- see below for options
        $ make
        $ ./update-usbids.sh            <-- optional
        $ su -c "make install"
        $

Significant options to "configure" include:

--prefix=/ To replace the normal /sbin version of lsusb, rather than /usr/local.

--enable-usbmodules If you're using a Linux 2.4 based system or otherwise not using "udev" for coldplug.

 

 

 

 

 

 

Sharon And Joy
 

Kernel Traffic is grateful to be developed on a computer donated by Professor Greg Benson and Professor Allan Cruse in the Department of Computer Science at the University of San Francisco. This is the same department that invented FlashMob Computing. Kernel Traffic is hosted by the generous folks at kernel.org. All pages on this site are copyright their original authors, and distributed under the terms of the GNU General Public License version 2.0.