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I upgrade my system (using the built-in upgrade mechanism) from 9.10 to 10.04.

My kernel is reported now as 2.6.32-24-generic (that means 32 bit, right?)

The systems seems to only be able to access 3.2GB, whereas 4GB are installed.

I read these instructions on solving this on 9.10: https://help.ubuntu.com/community/EnablingPAE

But it seems to imply the problem is already solved on 10.04 (which is not the case for me).

Is it safe to follow the instructions for 9.10 to enable PAE on my 10.04?

Thanks

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2 Answers 2

Procedure should be same.

However, do notice that procedure might not work.

Your computer (both CPU and BIOS) must support PAE. If your motherboard says that maximum supported RAM is 4 GB, you are probably out of luck.

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why? all I have is 4GB –  GJ. Aug 28 '10 at 18:42
    
It's pretty safe to assume that the OP's CPU and BIOS both support PAE since the question states it was enabled using the 9.10 procedure. –  Velociraptors Aug 28 '10 at 19:34
    
@Velociraptors: From question I deduce that he still hasn't tried this 9.10 procedure. Everything is still open. :) –  Josip Medved Aug 28 '10 at 21:23
    
@GJ: Yes, but hardware devices (e.g. graphic card) needs to have it's memory mapped into same 4 GB. This is what is really using your 4 GB limit. If motherboard does not support both PAE and memory remapping, it cannot move memory from under other devices area. That memory overlaps same range as existing hardware device and thus it is lost. –  Josip Medved Aug 28 '10 at 21:26

But it seems to imply the problem is already solved on 10.04 (which is not the case for me).

Actually, it says the installer will install the PAE kernel on new installations, which doesn't apply as you did an upgrade. So you should follow the instructions for 9.10.


And it's not true that the system can only access 3.2 GiB, what you see is that userspace applications can't use more than 3.2 GiB. The remaining 0.8 GiB might be used by things like the BIOS, BIOS extensions, graphics memory & the kernel.

(One advantage of using PAE would be the ability to use more than 4 GiB swap.)

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