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I'm running Ubuntu 10.10 Desktop x86_64 on a Mac mini 4.1 and it looks like I can only use one CPU core. It looks like the kernel supports SMP. I wish I could tell you whether it worked with Lucid, but I didn't notice.

Anybody know why this isn't working?

Here's some relevant output:

$ sudo dmidecode -s system-product-name

$ cat /etc/lsb-release 

$ uname -a
Linux harold 2.6.35-22-generic #35-Ubuntu SMP Sat Oct 16 20:45:36 UTC 2010 x86_64 GNU/Linux

EDIT: I should have included /proc/cpuinfo. This is what I used to confirm that I was only getting use out of one core. I've since performed a fresh install of x86 Maverick on the Mac mini (which was an exercise in frustration in itself) and now I have use of both cores. I never figured out why it didn't work in the first place.

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up vote 1 down vote accepted

Your Mac needs the grub-efi installed (with rEFIt), otherwise ubuntu starts with bios and then cannot recognize more than one core

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Initially, I booted directly from the CD and installed an MBR partition table and did not use rEFIt at all. I've been using it and successfully recognizing all cores for a few months now, but I first reinstalled OS X, repartitioned with Bootcamp, installed rEFIt, then installed Ubuntu and now I boot Ubuntu from the rEFIt menu. – Justin Force Mar 3 '11 at 17:54

Usually if you only have 1 CPU then you should only see one CPU. Seeing two cores is something you normally see in /proc/cpuinfo but this doesn't have to be the case.

Some Intel machines have bios settings for switching on the extra core duo core being treated like a separate cpu. For the mac it's probably not an issue. Can you test to make sure your computer is not using the second core and post the results of cat /proc/cpuinfo into your question.

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I've never seen multi-core CPUs presented in Linux in any way other than as multiple CPUs. Your answer also does not relate to my question, which pertains specifically to the interaction between Ubuntu Maverick and a Mac mini 4,1. – Justin Force Nov 5 '10 at 4:20
Then your question was ambiguous. Probably a kernel hicup – Martin Owens -doctormo- Nov 5 '10 at 8:17
My question was not ambiguous. The title of the question says "Mac mini 4,1" and it's tagged 10.10. And "kernel hicup?" What does that even mean? And this "hicup" persists between reboots? – Justin Force Nov 9 '10 at 17:23
yes. it's a hicup that was persistent. – Martin Owens -doctormo- Nov 9 '10 at 18:02

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