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I have a EEE PC 1025C which came pre-loaded with Windows 7 Starter Edition. I installed Ubuntu 12.04 32-bit as dual-boot with no difficulties. An output of uname -r gave an output of 3.4.0-030400-generic. A few weeks later, I installed a 4GB stick of RAM instead. I installed the PAE files using apt-get (linux-generic-pae and linux-headers-generic-pae). I also verified that the processor is PAE-capable by checking /proc/cpuinfo. However, the system still is not PAE-enabled (same output of uname as before). When I check my total memory using free -m, it says 3019, but BIOS tells me that all 4GB are there on the boot screen. What am I missing?

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You need to select the pae kernel from the boot menu, and, possibly, remove the non-pae ones, so that they don't confuse you. If you don't see the menu at boot, press the Shift key after the BIOS screen. –  mikewhatever Sep 30 '12 at 22:22
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Installing the PAE kernel is only part of it - you also have to update grub. Try running

sudo update-grub

and reboot to see if the PAE kernels show up on the grub menu.

Alternatively, you could reinstall with the 64 bit release. I also note that 3.4.0 is not a normal kernel release for 12.04. It should be 3.2.0-31-generic-pae

The normal generic kernels were removed from Ubuntu 12.04 some time after the initial release - the pae kernels are now the default. Generic kernels are still used for some releases such as Lubuntu. enter image description here

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When kernels are installed, grub gets auto-updated. The OP claims to have the 3.4 non-pae kernel that would always be higher on the boot list then 3.2 pae ones, no matter how many times it's updated. –  mikewhatever Oct 1 '12 at 0:19
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