#61: MacBook Pro network access slow on battery in 10.5.8

After upgrading to Mac OS X 10.5.8 on the MacBook Pro 15 in (early 2008), my wireless network speed plunges when on battery power, compared with adapter power. Ping to the nearest network router on AirPort Extreme should be ~1ms (and is when on adapter power) but increases to 300ms when the adapter is pulled.

Resetting the system power management unit (SMC) does NOT help.

Replace IO80211Family.kext with a previous version

If you're using Time Machine, this is simple enough. Pull a version of IO80211Family.kext (the AirPort driver) from before the system update.

If you're not, this involves grabbing the 10.5.7 combo updater and extracting the package (with Pacifist) for IO80211Family.kext. Once you get this file, remove the new copy and put your old one in its place in /System/Library/Extensions. Then, issue
kextcache -k /System/Library/Extensions/
to clear kernel extensions caches. Reboot and get back your AirPort speed even on battery power.

When replacing the broken kext, make sure that permissions are set properly on the new kext. On occasion, copying (via the Finder) will set owner, group, and their permissions for the .kext file to something unacceptable to the OS. For security reasons, kext files and their resources in /System/Library/Extensions need to be root:wheel owned. A Repair Permissions via Disk Utility is probably the best option, though you manually chown -R root:wheel /System/Library/Extensions/IO80211Family.kext as well.

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OS X kexts knowhow

http://blog.skaelede.net/archives/2007/02/07/os-x-kexts-knowhow/comment-page-1/# - found by 92049143cabb7ba896d7c06e19906303_small yliu on August 08, 2009, 11:03 PM UTC

clearing kernel caches after installing a new kernel extension

Tags: kext kernel extension OS X

Mac OS X 10.5.7 Combo Update

http://support.apple.com/downloads/Mac_OS_X_10_5_7_Combo_Update - found by 92049143cabb7ba896d7c06e19906303_small yliu on August 08, 2009, 10:33 PM UTC

The last working OS X version.

10.5.8 slow Airport when on battery

http://discussions.apple.com/thread.jspa?threadID=2106968&start=105&tstart=0 - found by 92049143cabb7ba896d7c06e19906303_small yliu on August 08, 2009, 10:31 PM UTC

and of course, there are other people bitching about already

Tags: discussions Apple forums