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aquaclear · May 7, 2003, 06:36 AM

I got a problem where I was experimenting with an application called Kismac. Well Kismac allows you to switch the kernel of Mac OSX to get a sleep function. It makes a backup of the original kernel however when I tried to restart the computer when into a kernel panic and requires a restart so I don't even make it to the signon screen. Does anyone know how to boot from a cd to use another kernel or a backdoor way for me to replace the kernel with the backup kernel?

I updated my OS to 2.2.6 and my cd is 2.2.4.

Thanks

aquaclear · May 7, 2003, 08:12 AM

Anyone? I really need help. I can't even start my computer. Please no flames about an idiotic thing of replacing the kernel but I am using this as a learning experience.

eevyl · May 7, 2003, 09:38 AM

You can try to boot from the Mac OS X install CD by pressing 'c' while starting up the computer (and the CD is in the drive of course)

What I don't understand is the purpose of the kernel swap... to get a sleep function? I bet Mac OS X already have that...

warpmoon · May 7, 2003, 09:57 AM

KisMAC, enable sleep functions on you mac? And here I thought that KisMAC was a wireless sniffer program... Why lie about it?

Anyway, as suggested, inserting a bootable cd and holding down "c" when starting will allow you to switch back to your unmodified kernel. (you need to use one which will allow you to access the Finder)

Failing that, if you have Mac OS 9 installed on a partition, you can hold down "alt" (or "option") when restarting, this will allow you to pick which system to boot.

fitter · May 7, 2003, 10:02 AM

See if you can boot into single user mode by holding down command+s during startup. You'll boot into the text console. First, run a file system check:

fsck -y

Mount the drive:

mount -uw /

Move the bad kernel out of the way:

mv /mach_kernel /mach_kernel.bad

Move the good kernel back into place:

mv /mach_kernel.old /mach_kernel

There's a chance you may not get this far, if the kernel panic occurs before a complete single user boot. In that case, you can try single user booting from the CD. Hold down 'c' while booting, and as soon as you see the apple logo come up, hold down command+s. Things get much more complicated from there. Hopefully the above will work for you.

aquaclear · May 7, 2003, 12:33 PM

Thanks for the help. I will try this tonight. In regard to the inquiries about Kismac, I am not trying to hide the main abilities of Kismac, just addressing the portion that is giving me the problem. I don't need to address that it is a wireless sniffer because if you don't know what Kismac is then you probably do not need to be messing around with it. This was a project that I expected to possibly screw up because the sleep portion is alpha. If anyone knows how to turn off sleep on an ibook then I am all ears as well. I know Apple would not endorse such a feature as the heat issue would void warranties and etc...

Thanks Again

aquaclear · May 7, 2003, 10:50 PM

Fitter,

I tried to use your first method but it appears that I had to resort to booting off the cd and then getting into the console via command + s. The thing is it gives me the command line but it would appear that / is now off from the cd and not from the harddrive. Am I missing something? I tried to mount -uv / but again I think it was trying to mount the cd / . Any suggestions?

If anything, I could reinstall. Will it leave all my files intact if I do not do a clean install and do more or less a repair install?

Thanks

mqa · 05:06 AM

I did this myself a while back, and here is how I fixed it: What you need to do is to boot in to os9 either via CD or by holding down the option key as you startup your computer. Then through os9, open your hard drive and exchange "mach_kernel" with "mach_kernel.backup" This should restore your computer.

I hadn't yet tried the kernel swap yet for 10.2.6, and am saddened to learn it doesn't work, although if it is that important for you to be able to run your computer with the lid closed you can always downgrade to 10.2.5.

aquaclear · May 8, 2003, 06:59 AM

Well, I don't want to use OS 9 as a solution as everything I have is OS X. But yes the sleep option to Kismac will render your system inoperatable unless you can find a way to backup the kernel. The "solution" I took was to reintall OS X but do not do the complete istall or the one that erases your disk. The option I took created a new system folder and archives your old system folder. You can then access your user files and backup to then hose your system and reinstall everything fresh if you want or if someone knows which files to replace to hose the archived system folder than that can be done too. It required 2 GB of space to reinstall by the way.

mqa · May 8, 2003, 07:14 PM

Yeah, I know about the archive install, but at the time I had only 300MB free on my hard drive.

Along those lines, Apple really should provide a way to boot OSX off the CD. It's sort of ridiculous to have to install 2GB of files just to repair a 3.5MB file! In the future you might want to try BootCD so you dont have to reinstall every time your kernel experiments go awry.

Finally if you haven't already, you should drop a line to kismac's author to let him know that 10.2.6 has broken his hack again.