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I just installed the pae kernel but it's still not recognizing over 3 gigs of memory? Anyone have a suggestion as to what might cause this issue? I have ubuntu ...
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  1. #1
    Linux User hatebreed's Avatar
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    PAE kernel


    I just installed the pae kernel but it's still not recognizing over 3 gigs of memory? Anyone have a suggestion as to what might cause this issue? I have ubuntu 9.10 with the pae 2.6.31.23 kernel and kernel headers installed.

  2. #2
    Administrator jayd512's Avatar
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    It's been a while since I compiled a kernel, so take this for what it's worth
    When doing menuconfig, did you set the option for high memory? If I recall, there is an option for systems running 2 GB, 4, and 64. (Little hazy on that...)
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    Linux User hatebreed's Avatar
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    i got the pae kernel from synaptic. doesn't it work from the get go once installed?

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    Linux Guru Rubberman's Avatar
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    Have you enabled PAE in your BIOS yet? You may need to do that first. Also, are you sure your system supports PAE?
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

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    Administrator jayd512's Avatar
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    Quote Originally Posted by hatebreed View Post
    i got the pae kernel from synaptic. doesn't it work from the get go once installed?
    The kernel itself, once installed, will work. But if you haven't enabled high mem support, then it's possible that it may only be ready for 2 GB RAM.
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    Quote Originally Posted by Rubberman View Post
    Have you enabled PAE in your BIOS yet? You may need to do that first. Also, are you sure your system supports PAE?
    As far as I'm aware a PAE kernel will panic on a non PAE CPU. This is due to the lack of NX bit support in non PAE CPUs. Debian is now transitioning to 686-pae kernel builds and phasing out the old 686 builds, which means those running older CPUs are having to switch to 486 kernels (no big deal actually). I would expect 'buntu to do the same if they haven't already. It's likely that the CPU in question supports PAE, but it's simply disabled in the BIOS. Enable it and it should be fine.

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    Linux User hatebreed's Avatar
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    i don't have a pae option in bios to enable. and yes the processor supports pae. why would you have to set high mem support on a kernel that is meant for that very purpose? any other ideas, I may just try the 64 bit ubuntu. I just didn't want to reinstall and have to worry about some things not working properly. Like drivers and so forth.

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    If it's turned off in the BIOS then your kernel will not see it. If there's no option anyway then it must be always enabled, so I'm not sure why it isn't seeing the rest of your RAM.

    If you have a 64 bit CPU then you would be much better off with an amd64 kernel. You can install an amd64 kernel on your current install if you wish, but you'd be much better off doing a complete reinstall (64 bit kernel/64 bit userland).

    Are you sure you're running the pae kernel however? Post the output:

    Code:
    uname -r
    Also consider installing/compiling a newer kernel - 2.6.31 is quite old. Unless you've any particular reason for running the 9.10 release you could upgrade to their "LTS" release or choose another distro with a newer kernel.

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    Linux User hatebreed's Avatar
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    I did a uname -r and it came up with the pae kernel. is there something i'm missing to enable the highmem64? I've been reading posts on line but I can't seem to find anything that relates to my problem. I'm thinking about going to the 64 bit version but I don't want to run into problems with software compatibility. any suggestions?

  10. #10
    Linux Guru Rubberman's Avatar
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    I've been running pure 64-bit for 4 years now without problems. You can still install and run 32-bit apps as well, but now that there is a 64-bit flash plugin for Linux, the main complaint about not being able to YouTube from your browser is gone.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

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