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{{Languages|UbuntuHelp:EnablingPAE}}
 
{{Languages|UbuntuHelp:EnablingPAE}}
 
#Enabling_PAE
 
#Enabling_PAE
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=== Why? ===
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== What is PAE? ==
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Originally, 32 bit operating systems could only access up to 4 Gb of memory, and for various reasons, some of that memory isn't available, leaving some people with 32 bit operating systems with only around 3 Gb of memory. Luckily, Ubuntu isn't just any operating system, it supports Physical Address Extension (and doesn't cripple it, unlike certain other operating systems). [http://en.wikipedia.org/wiki/Physical_Address_Extension Physical Address Extension] allows 32 bit operating systems to use up to 64 Gb of memory, and is supported on all Intel processors starting with the Pentium Pro, and all AMD processors since the Athlon (and if you have more than 4 Gb of memory you probably have a processor that supports PAE). Unfortunately, PAE is not enabled by default in Ubuntu, but it's easy to do. All we need to do is install a PAE enabled kernel, like the server kernel.
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[http://en.wikipedia.org/wiki/Physical_Address_Extension Physical Address Extension] is a technology which allows 32 bit operating systems to use up to 64 Gb of memory (RAM), something which is normally achieved by switching to a 64 bit system. PAE is supported on the majority of computers today and it is an easy procedure to enable it in Ubuntu, if it is not already.
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From what I've read, there shouldn't be a speed difference between 32 bit Ubuntu generic vs 32 bit Ubuntu server (PAE), but 64 bit Ubuntu generic should out-perform both. If you have the option, you should probably just install the amd64 version of Ubuntu.
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In general, a proper 64 bit system is recommended if you have 4 Gb or more memory and/or want to get the full benefit of the 64 bit architecture (see [[UbuntuHelp:32bit_and_64bit|32bit_and_64bit]]), but in some cases making a complete switch to 64 bit is not desirable, and using PAE can be a viable compromise.
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However, if you want to use all of your 3+ Gb of memory
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== How to Enable PAE ==
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Of course, 64 bit processors will do most things faster in 64 bit mode, so it's always recommended that you use the amd64 version of Ubuntu if you can, but for various reasons, some people need to run Ubuntu in 32 bit mode.
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=== Ubuntu 10.04 LTS (Lucid Lynx) ===
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=== How ===
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Both the CD and DVD installer of Ubuntu 10.04 automatically installs the PAE enabled kernel if it detects more than 3 Gb of available memory.
 +
In the case of the liveCD, a working network connection is required, since the PAE enabled kernel packages are not present on the CD.
 +
If you need to enable PAE manually, follow the instructions for Karmic below.
 +
=== Ubuntu 9.10 (Karmic Koala) ===
 +
The PAE enabled kernel can be installed using the Synaptic Package Manager (accessible from the System menu under Administration -> Synaptic Package Manager):
 +
The relevant packages are called "linux-generic-pae" and "linux-headers-generic-pae" and should be easily found with a search for "pae".
 +
Alternatively they can be installed using either apt-get or aptitude through the terminal:
 +
<pre><nowiki>
 +
sudo aptitude install linux-generic-pae linux-headers-generic-pae
 +
</nowiki></pre>
 +
After a reboot the PAE kernel should be booted as the default option in the GRUB boot menu.
 +
To confirm that PAE was enabled correctly you can use the system monitor form the System menu under Administration -> System Monitor. The first tab shows usable memory.
 +
==== DVD installer ====
 +
If installing from the DVD version of Ubuntu 9.10 (both live and alternate), it will automatically install the PAE enabled kernel if it detects more than 3 Gb of available memory, it should work straight out of the box.
 +
=== Earlier versions (Ubuntu 9.04 and  earlier) ===
 +
Prior to Ubuntu 9.10, there are no specific PAE-enabled kernels for the desktop version, however the server kernels comes with PAE enabled. So by installing and running these, PAE can be used in the desktop version of ubuntu.
 
First, turn off any restricted drivers. We'll turn them back on once we're done, but if you don't turn them off first, X won't start, and that's bad. Just go into System -> Administration -> Hardware Drivers and turn off your graphics drivers.
 
First, turn off any restricted drivers. We'll turn them back on once we're done, but if you don't turn them off first, X won't start, and that's bad. Just go into System -> Administration -> Hardware Drivers and turn off your graphics drivers.
 
Next we just install the server kernel:
 
Next we just install the server kernel:
 
<pre><nowiki>
 
<pre><nowiki>
−
sudo aptitude install linux-image-server
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sudo aptitude install linux-server linux-headers-server
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</nowiki></pre>
+
−
In Karmic, the server kernel has been replaced by the PAE kernel:
+
−
<pre><nowiki>
+
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sudo aptitude install linux-image-generic-pae
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−
</nowiki></pre>
+
−
You might also want the restricted modules:
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−
<pre><nowiki>
+
−
sudo aptitude install linux-restricted-modules-server
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</nowiki></pre>
 
</nowiki></pre>
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It's worth nnoting that Karmic replaced linux-restricted in favor of dkms.
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After a reboot the PAE kernel should be booted as the default option in the GRUB boot menu. Once you're at the desktop, re-enable your restricted drivers (System -> Administration -> Hardware Drivers).
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Now restart, and your first boot option should be ubuntu-something-server (-generic-pae in Karmic). Once you're at the desktop, re-enable your restricted drivers (System -> Administration -> Hardware Drivers).
+
To confirm that PAE was enabled correctly you can use the system monitor form the System menu under Administration -> System Monitor. The first tab shows usable memory.
−
If everything worked right, you should have 4 Gb of memory enabled. You can use the system monitor to confirm this: System -> Administration -> System Monitor. The first tab shows usable memory.
+
=== Removing non-PAE kernels ===
−
=== Removing old kernels ===
+
If PAE was successfully enabled you may want to remove the meta-packages for the normal kernel, to
−
If everything went ok, you probably don't want Ubuntu to keep installing updates for the generic kernel, so remove the generic kernel meta-package:
+
If everything went ok, you probably don't want Ubuntu to keep installing updates for the generic kernel, so remove the generic kernel meta-packages:
 
<pre><nowiki>
 
<pre><nowiki>
−
sudo aptitude remove linux-image-generic
+
sudo aptitude remove linux-generic linux-image-generic linux-headers-generic
 
</nowiki></pre>
 
</nowiki></pre>
 
If you want to remove all of the old kernels from your boot menu, it seems like you have to do it all manually:
 
If you want to remove all of the old kernels from your boot menu, it seems like you have to do it all manually:
 
<pre><nowiki>
 
<pre><nowiki>
−
sudo aptitude remove linux-image-<numbers go here>-generic
+
sudo aptitude remove linux-image-<version number>-generic linux-headers-<version number>-generic
 
</nowiki></pre>
 
</nowiki></pre>
−
There should be some way of doing wildcards in aptitude, but I can't figure it out. You basically want to remove linux-image*generic, but I don't know how.
+
==== Something went wrong ====
−
=== Something went wrong ===
+
 
If something went wrong, just remove the server kernel and use your old kernels. They should still be there. Make sure to turn off the restricted drivers when switching between them. You can remove the server kernel with:
 
If something went wrong, just remove the server kernel and use your old kernels. They should still be there. Make sure to turn off the restricted drivers when switching between them. You can remove the server kernel with:
 
<pre><nowiki>
 
<pre><nowiki>
−
sudo aptitude remove linux-image-server linux-image-<version number goes here>-server
+
sudo aptitude remove linux-server linux-headers-server linux-image-server linux-image-<version number>-server linux-headers-<version number>-server
 
</nowiki></pre>
 
</nowiki></pre>
 
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2010年5月19日 (三) 22:13的最新版本

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https://help.ubuntu.com/community/EnablingPAE

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English

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  1. Enabling_PAE

What is PAE?

Physical Address Extension is a technology which allows 32 bit operating systems to use up to 64 Gb of memory (RAM), something which is normally achieved by switching to a 64 bit system. PAE is supported on the majority of computers today and it is an easy procedure to enable it in Ubuntu, if it is not already. In general, a proper 64 bit system is recommended if you have 4 Gb or more memory and/or want to get the full benefit of the 64 bit architecture (see 32bit_and_64bit), but in some cases making a complete switch to 64 bit is not desirable, and using PAE can be a viable compromise.

How to Enable PAE

Ubuntu 10.04 LTS (Lucid Lynx)

Both the CD and DVD installer of Ubuntu 10.04 automatically installs the PAE enabled kernel if it detects more than 3 Gb of available memory. In the case of the liveCD, a working network connection is required, since the PAE enabled kernel packages are not present on the CD. If you need to enable PAE manually, follow the instructions for Karmic below.

Ubuntu 9.10 (Karmic Koala)

The PAE enabled kernel can be installed using the Synaptic Package Manager (accessible from the System menu under Administration -> Synaptic Package Manager): The relevant packages are called "linux-generic-pae" and "linux-headers-generic-pae" and should be easily found with a search for "pae". Alternatively they can be installed using either apt-get or aptitude through the terminal: 

sudo aptitude install linux-generic-pae linux-headers-generic-pae

After a reboot the PAE kernel should be booted as the default option in the GRUB boot menu. To confirm that PAE was enabled correctly you can use the system monitor form the System menu under Administration -> System Monitor. The first tab shows usable memory.

DVD installer

If installing from the DVD version of Ubuntu 9.10 (both live and alternate), it will automatically install the PAE enabled kernel if it detects more than 3 Gb of available memory, it should work straight out of the box.

Earlier versions (Ubuntu 9.04 and earlier)

Prior to Ubuntu 9.10, there are no specific PAE-enabled kernels for the desktop version, however the server kernels comes with PAE enabled. So by installing and running these, PAE can be used in the desktop version of ubuntu. First, turn off any restricted drivers. We'll turn them back on once we're done, but if you don't turn them off first, X won't start, and that's bad. Just go into System -> Administration -> Hardware Drivers and turn off your graphics drivers. Next we just install the server kernel: 

sudo aptitude install linux-server linux-headers-server

After a reboot the PAE kernel should be booted as the default option in the GRUB boot menu. Once you're at the desktop, re-enable your restricted drivers (System -> Administration -> Hardware Drivers). To confirm that PAE was enabled correctly you can use the system monitor form the System menu under Administration -> System Monitor. The first tab shows usable memory.

Removing non-PAE kernels

If PAE was successfully enabled you may want to remove the meta-packages for the normal kernel, to If everything went ok, you probably don't want Ubuntu to keep installing updates for the generic kernel, so remove the generic kernel meta-packages: 

sudo aptitude remove linux-generic linux-image-generic linux-headers-generic

If you want to remove all of the old kernels from your boot menu, it seems like you have to do it all manually: 

sudo aptitude remove linux-image-<version number>-generic linux-headers-<version number>-generic

Something went wrong

If something went wrong, just remove the server kernel and use your old kernels. They should still be there. Make sure to turn off the restricted drivers when switching between them. You can remove the server kernel with: 

sudo aptitude remove linux-server linux-headers-server linux-image-server linux-image-<version number>-server linux-headers-<version number>-server
取自“https://wiki.ubuntu.org.cn/index.php?title=UbuntuHelp:EnablingPAE&oldid=138803”