MacBookPro 7,1 can only see one cpu

Posted by gozzilli on Ask Ubuntu See other posts from Ask Ubuntu or by gozzilli
Published on 2011-11-20T23:47:27Z Indexed on 2012/03/21 23:40 UTC
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macbook

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cpu

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multi-core

On a MacBookPro 7,1 running ubuntu 11.10, System monitor only sees 1 core (instead of 2).

cat /proc/cpuinfo | grep 'cpu cores'

also gives:

cpu cores   : 1

I followed this guide and added acpi_apic_instance=2 to the line with GRUB_CMDLINE_LINUX_DEFAULT, but that doesn't seem to change the situation.

What can I do? I'm using rEFIt, installed under MacOS, and running in dual boot with MacOS. After the rEFIT menu, I'm still presented with the GRUB menu (I'm assuming that's normal).

I saw similar posts on this matter, but could not fix my problem with what they suggested.

EDIT: With the method mentioned above the computer runs sometimes with 1 core and other times with 2. Why is that? How can it be fixed?

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