How to Enable PAE?

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luckygrl
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Iscritto: 05/26/2014

Hello, on a number of old laptops I get the following problem when I try to install Trisquel....

The ISO image will fail to boot ("This kernel requires the following features not present on the CPU: pae.") If a few lines above this text there is a warning "WARNING: PAE disabled.

Can anyone please suggest a safe way to fix this?

thankyou

onpon4
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Iscritto: 05/30/2012

PAE is Physical Address Extension:

https://en.wikipedia.org/wiki/Physical_Address_Extension

This is only for IA-32 (the 32-bit processor type, also called "x86"), not AMD64 (the 64-bit variant of IA-32, also called "x86-64"), so if you have a 64-bit processor, you can (and should) use the 64-bit Trisquel. I don't know whether or not any AMD64 processors without PAE support exist.

If you really have a 32-bit processor without PAE support, you'll need to get a distro with a non-PAE kernel option. Supposedly[1] these are usually labelled "i386", "i486", or "retro". Maybe gNewSense would be an option (I can't check since the gNewSense website isn't loading for me at the moment).

[1] https://en.wikipedia.org/wiki/Physical_Address_Extension#Linux

Legimet
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Iscritto: 12/10/2013

Try booting with the "forcepae" kernel option.

luckygrl
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Iscritto: 05/26/2014

Thankyou, could you please tell me how to boot with forecepae?

mYself
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Iscritto: 01/18/2012

Can you specify which version you're trying to install?

luckygrl
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Iscritto: 05/26/2014

Thankyou, I got it to work with forcepae with the following....
Boot from the installation CD or USB stick
Press escape to see the boot menu
Highlight the Install Trisquel; option
Press F6 to open the menu for adding additional boot options
Press escape to close the menu, because the forcepae option is available as a preset
A string with boot options shows now
Put the cursor at the end and add: forcepae;
Press Enter and the installation should continue now

Ra
Ra
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Iscritto: 07/23/2014

I have the same problem. At what point do you "Press escape to see the boot menu"? I don't get to any boot menu where i can choose whether to install or to just test. I know that menu from the install process of other distros.

Ra
Ra
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Iscritto: 07/23/2014

What i wrote was true of trisquel 7. Booting a usb stick with trisquel 6 i automatically get to the live session. There, when i click on Install, the computer is busy for around half a minute, but nothing happens.
Can i switch on forcepae via the terminal, once i am in the live session?

lembas
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Iscritto: 05/13/2010

>Can i switch on forcepae via the terminal, once i am in the live session?

No, it's a parameter for the kernel. Once you've booted up it's too late.

Try holding Shift to get to the grub menu. It should offer you a way to edit the kernel parameters.

Looking at this https://www.kernel.org/doc/Documentation/kernel-parameters.txt I get the impression forcepae only works on 32 bit.

Legimet
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Iscritto: 12/10/2013

PAE is only for 32-bit, so that makes sense. On 32-bit trisquel, the PAE kernel is used by default. Many 32-bit systems have PAE support but disable it, so forcepae enables it. If you don't have PAE support at all, you will have to use a non-PAE kernel.

sebelius
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Iscritto: 08/22/2013

I know you can choose between many different kernels, when installing using the 'net install' (at least for Trisquel 6.0).