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Thread: Kernel requires cmov feature - 12.04 LTS install hangs

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  1. #1
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    Kernel requires cmov feature - 12.04 LTS install hangs

    My XUbuntu 12.04 LTS installation hangs with the message:
    This kernel requires the following features not present on the CPU:
    cmov
    Unable to boot - please use a kernel appropriate for your CPU.
    My CPU is an AMD K6-2 3D 550 MHz (year 2000) on a fast board with 256 MB memory and an ad-on RAID controller. (It's quick!).

    Before I bothered to completely rebuild, upgrade and heavily optimize my old rig I tested with XUbuntu 12.04 beta and I could have sworn that it worked! I overwrote the beta version when I downloaded the released version 12.04 LTS (I waited for it). Now I can't even install it. I thought XUbuntu was especially designed to run on older hardware? What's wrong?
    How can I fix it.
    Are more people experiencing the same problem?
    Last edited by martinr; May 19th, 2012 at 01:48 PM. Reason: typo
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  2. #2
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    Re: Kernel ruiquires cmov feature - 12.04 LTS install hangs

    yup it will not completely sure but I am pretty sure that error is telling you that your CPU does not have on board pae and starting with version 12.04 the 32 bit has to support pae ..

    how ever at this time lbuntu xbuntu still work without as I understand it in the near future they will no longer work on older cpu either the only way to run will be upgrades..

    they are moving from support for these older processors

    check here

    http://www.adminreseau.fr/how-to-ins...able-hardware/


    also try burning an ISO os version 11.04 or 11.10 and then try to upgrade using your 12.04 cd or an online upgrade
    Last edited by jadtech; May 18th, 2012 at 07:39 PM.

  3. #3
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    Re: Kernel ruiquires cmov feature - 12.04 LTS install hangs

    Thanks for you reply.
    What is pae and why do you need it?
    Is it mandatory in Open Office now?
    Will email bounce without it?

    Does somebody know where I can get my hands again on:
    http://xubuntu.org/news/beta-2-released-new-branding/

    I could have sworn that worked.

    I can't believe that WinXP runs like a charm out of the box and XUbuntu doesn't even support my rig anymore? Lets scrap the planet with perfectly working hardware.
    Last edited by martinr; May 18th, 2012 at 07:48 PM. Reason: frustration
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  4. #4
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    Re: Kernel ruiquires cmov feature - 12.04 LTS install hangs

    pae lets the cpu address morethen 3gb of ram like fake 64bit more of less

    pae allows the system to handle a far larger more efective memmory file system , xp I dont believe was true 64bit OS though it could run on 64 bit you could load 20 gb of ram in a machine with xp it would still only address and use 2 gb ...
    Last edited by jadtech; May 18th, 2012 at 07:56 PM.

  5. #5
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    Re: Kernel ruiquires cmov feature - 12.04 LTS install hangs

    Quote Originally Posted by jadtech View Post
    pae lets the cpu address morethen 3gb of ram like fake 64bit more of less
    Great, I don't even need that much SWAP.
    You wrote that 12.04 does work without pae. Is there a way around the installer?
    Heck, have you ever printed out 1MB of text? It looks like a phone book. Now the basic install entails provisions for 3000000 phone books of text. We're using up too much resources, if you'd ask me (the things that I do with a computer are not that different from 15 years ago). Ah well, lets have a beer.
    To fail to prepare is to prepare to fail.

  6. #6
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    Re: Kernel ruiquires cmov feature - 12.04 LTS install hangs

    Quote Originally Posted by martinr View Post
    Great, I don't even need that much SWAP.
    You wrote that 12.04 does work without pae. Is there a way around the installer?
    Heck, have you ever printed out 1MB of text? It looks like a phone book. Now the basic install entails provisions for 3000000 phone books of text. We're using up too much resources, if you'd ask me (the things that I do with a computer are not that different from 15 years ago). Ah well, lets have a beer.
    yeah the link I posted shows the way to a mini ISO that will install 12.04 on that processor the istall will be text based and void of a lot of things you will have to add from repository after install ..

    if all you have a lite duty might try puppy linux
    Last edited by jadtech; May 18th, 2012 at 08:05 PM.

  7. #7
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    Re: Kernel requires cmov feature - 12.04 LTS install hangs

    Quote Originally Posted by martinr View Post
    I tested with XUbuntu 12.04 beta and I could have sworn that it worked!
    I was able to retest the beta2 and it also runs into the same missing CMOV trouble. I was mistaken and probably tested the beta2 before the processor upgrade. Although the K6-2 is 3 times as fast as the Pentium, it's lacking a complete set of CMOV instructions.
    To fail to prepare is to prepare to fail.

  8. #8
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    Re: Kernel requires cmov feature - 12.04 LTS install hangs

    Does somebody know what Ubuntu software is impacted by the lack of a complete set of CMOV instructions in the processor? (e.g. only impacts kernel vs impacts X11 directly, etc).

    In the pre-installation manual of 12.04 I found the following:
    Code:
    However, Ubuntu precise will not run on i586 or earlier processors. Despite the architecture name "i386", support for actual 80386 processors (and their clones) was dropped with the Sarge (r3.1) release of Debian[2]. (No version of Linux has ever supported the 286 or earlier chips in the series.) Support for i586 and lower processors, as well as for i686 processors without the cmov instruction, was dropped in Ubuntu 10.10. Most i686 and later processors are still supported[3].
    Where references 2 and 3 point to:
    Code:
    
    [2] We have long tried to avoid this, but in the end it was necessary due a unfortunate series of issues with the compiler and the kernel, starting with an bug in the C++ ABI provided by GCC. You should still be able to run Ubuntu on actual 80386 processors if you compile your own kernel and compile all packages from source, but that is beyond the scope of this manual.
    
    [3] Many Ubuntu packages will actually run slightly faster on modern computers as a positive side effect of dropping support for these old chips. The i486, introduced in 1989, has three opcodes (bswap, cmpxchg, and xadd) which the i386, introduced in 1986, did not have. Previously, these could not be easily used by most Ubuntu packages; now they can.
    This talks about dropping support for the i486, introduced in 1989 and not about the i686 (AMD K6-2) without a complete set of CMOV instructions.

    Does somebody know what Ubuntu software is impacted by the lack of a complete set of CMOV instructions in the processor?
    Last edited by martinr; June 29th, 2012 at 10:52 PM.
    To fail to prepare is to prepare to fail.

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