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  1. #1
    vikingshelmut's Avatar
    vikingshelmut is offline 100% Bull Plop
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    Removing "kext" kernel extensions

    Just wanted to ask everybody their thoughts regarding removing unnecessary kernel extensions from the "extensions" folder in os X. I've noticed extensions in there for ADB, SCSI, and other devices that I don't use, or ever plan on using. Is it save to remove a kext from the extensions folder? From what I understand, these are treated similar to extensions in 9, but I might be wrong. Are there other references to a kext in the system that could cause a problem when booting?

    I might be wrong, but I just figured that at startup, the system looks in this directory, and if anything is present, loads it into the kernel. There is a lot of stuff in there that I don't need, so I want to get rid of it (backed up of course), to hopefully produce a smaller, more stable kernel (less kernel panics!).

    Anybody test this out? Any negative results? Let me know!

  2. #2
    Alexandert's Avatar
    Alexandert is offline gonneawaycameback
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    Try it!
    But in Linux the Kernel knows what to load. If somethings missing...
    Best wishes,
    Alex

    Athlon XP 1900+, Ge-Force 4 Ti 4400, 512MB DDR RAM, 80GB HD (ATA 133), ZIP 100MB, TEAK CD-RW 40/12/48, USB 2.0/FireWire PCI, USB 2.0 onboard, BlueTooth onboard, DSL-Router, Ethernet Hub, 768kb/s DSL, Philips DVD-ROM;

    beige G3 500MHz, 768MB RAM, 30GB + 10GB + 60GB HD, USB/FireWire UpgradeCard,
    ATA 100 Card, ZIP, Jaz, TDK Cyclone CDRW 24/10/40, DVD, Radeon PCI,
    LaserWriter; 6 other macs;

  3. #3
    blb
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    Actually, looking at /etc/rc, it appears the cache should be rebuilt if anything in the Extensions directory is changed (the -ot part):

    Code:
    if [ ! -f /System/Library/Extensions.mkext -o \
         /System/Library/Extensions.mkext -ot /System/Library/Extensions ]; then
    # rebuild cache here
    So anytime anything updates the /System/Library/Extensions directory, a reboot should rebuild it.

  4. #4
    blb
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    Of course, since kernel extensions are only loaded on a need-basis, deleting them shouldn't affect performance much (only when rebuilding that cache).

    To see what extensions are currently loaded, run

    Code:
    sudo kmodstat
    According to my system, 63 are currently loaded.
    Also, note, there are (on my system anyway) 104 .kext directories under /System/Library/Extensions but there are many more than this, as some kext's have kext's inside (ie, /System/Library/Extensions/IOUSBFamily.kext/Contents/PlugIns/IOUSBUserClient.kext).

  5. #5
    vikingshelmut's Avatar
    vikingshelmut is offline 100% Bull Plop
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    Good info!

    Thanks for the quick responses. Some quick questions, though.

    The rebuild cache process - this happens at every startup? If so, then this is theoretically like restarting 9 to unload an extension from memory (except that kext files arn't loaded in memory?)

    So, why does apple have all these kexts installed on machines which don't require that kext. Shouldn't the installer be able to recognize that that new G4 Dual 1ghz you have on your desk doesn't have a freakin' ADB port?


    Anybody actually test this out?

  6. #6
    Alexandert's Avatar
    Alexandert is offline gonneawaycameback
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    YOUR MAC DOES NOT LOAD THE EXTENSIONS YOU DONT NEED!!!
    Use the command above to see what is loaded!
    Best wishes,
    Alex

    Athlon XP 1900+, Ge-Force 4 Ti 4400, 512MB DDR RAM, 80GB HD (ATA 133), ZIP 100MB, TEAK CD-RW 40/12/48, USB 2.0/FireWire PCI, USB 2.0 onboard, BlueTooth onboard, DSL-Router, Ethernet Hub, 768kb/s DSL, Philips DVD-ROM;

    beige G3 500MHz, 768MB RAM, 30GB + 10GB + 60GB HD, USB/FireWire UpgradeCard,
    ATA 100 Card, ZIP, Jaz, TDK Cyclone CDRW 24/10/40, DVD, Radeon PCI,
    LaserWriter; 6 other macs;

  7. #7
    Aqualung is offline Banned
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    Might as well leave them in case you need them in the future. They don't take up much HD space, and OS X only loads them when needed.

    Habits from using OS 9 are no longer useful. These extensions aren't like OS9's, where the fewer, the better.

  8. #8
    stormbringer's Avatar
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    sudo kmodstat

    When issuing this command from terminal, what user are you logged in as? When I try this from the command line (looged in as a user with admin permissions) the systems next response is <Password:>. When I type in my password it responses with <sudo: kmodstat: command not found>??!!

    I used this command before when trouble shotting my Adaptec card! That was under 10.1.5. Would 10.2.4 make a difference?

 

 
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