Installing Apple's Updates can Render Your Mac Unbootable and how to Prevent it

From Unsanity

When you see the "Optimizing System Performance" phase of a software update, Mac OS X is really updating prebinding. Updating prebinding has a very, very nasty bug in it (look at _dyld_update_prebinding). If multiple processes are updating prebinding at the same time, then it is possible for a system file to be completely zero'd out. Basically, all data in the file is deleted and it is replaced with nothing. This bug is usually triggered when updating Mac OS X and every update to Mac OS X has the potential to render your system unbootable depending on if the "right" file is deleted or not. It's triggered during the "Optimizing System Performance" phase of installing an update. This phase is actually just running update_prebinding. If you launch an application that links to libraries that are not yet prebound, there is a chance one of those files will be zero'd out as dyld automatically redoes the prebinding on that file.

I've been tracking this particular bug for about 18 months now.

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10.4.9 update killed my Macbook

I installed 10.4.9 on my MacBook (No haxies of any kind installed on it) last week and when it tried to reboot it got stuck on the grey screen with the black apple logo and the spinning spokes. I had to do an archive and install to fix it. Now I am to scared to update my old G4, that actually has data on it that I would not like to loose - sure everything is backed up but still.

James
jamesema [at] mac [dot] com
http://web.mac.com

10.4.9 on PB G4 17

I've been running with it since the day after release. No problems whatsoever. While you've not provided any detail that might provide indication of your issue's cause, I think it fair to say (at least for 10.4.8 PPC units and based upon posted details at the MacFixit Forum) there doesn't seem to be any intrinsic issue with this 10.4.9 PPC update. So, I recommend carefully running systems utilities on all your Macs, checking various 3rd party software for compatibility, etc. (Of course, make some good backups.) Once completed, then follow recommended update procedures (maybe, visit MacFixit Forums for those details), which includes updating with the respective, Combo update. I've done so, since Jaguar, and never experienced an issue with any update / upgrade.

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