How much memory can a 32-bit kernel address? - Setup

This is a discussion on How much memory can a 32-bit kernel address? - Setup ; I have a 32-bit system with 4GB of memory. How much more memory can I add to it? Thanks. -- Hemant Shah /"\ ASCII ribbon campaign E-mail: NoJunkMailshah@xnet.com \ / --------------------- X against HTML mail TO REPLY, REMOVE NoJunkMail / ...

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Thread: How much memory can a 32-bit kernel address?

  1. How much memory can a 32-bit kernel address?


    I have a 32-bit system with 4GB of memory.
    How much more memory can I add to it?

    Thanks.


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  2. Re: How much memory can a 32-bit kernel address?

    On Fri, 19 Oct 2007 16:47:25 +0000, Hemant Shah wrote:

    >
    > I have a 32-bit system with 4GB of memory.
    > How much more memory can I add to it?
    >
    > Thanks.


    As memory serves, I believe you could add 60gb - you might want to check
    wikipedia for details.


  3. Re: How much memory can a 32-bit kernel address?

    Hemant Shah wrote:
    > I have a 32-bit system with 4GB of memory.
    > How much more memory can I add to it?
    >
    > Thanks.
    >
    >

    I have a 32-bit system with 8 GBytes of memory. If I used 2 GByte memory
    modules instead of the 1 GByte modules I have, I could go up to 16 GBytes.
    That is the limit of the motherboard.
    The Intel E7501 chipset allows me to go to 64 GBytes. I have 32-bit Xeon
    processors. I run the kernel-PAE-2.6.18-8.1.14.el5 from Red Hat.

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  4. Re: How much memory can a 32-bit kernel address?

    On Fri, 19 Oct 2007 16:47:25 +0000, Hemant Shah wrote:


    > I have a 32-bit system with 4GB of memory. How much more memory can I
    > add to it?
    >
    > Thanks.



    I think you're at the limit. 32bits all set to one is about 4096MB (4GB)


  5. Re: How much memory can a 32-bit kernel address?

    In comp.os.linux.advocacy, Hemant Shah

    wrote
    on Fri, 19 Oct 2007 16:47:25 +0000 (UTC)
    :
    >
    > I have a 32-bit system with 4GB of memory.
    > How much more memory can I add to it?


    Need a little more info. If you're running on a Xeon/PAE,
    apparently you can have up to 64 gigabytes, even on a
    32-bit architecture, through use of the Physical Address
    Extension (PAE).

    http://www.sybase.com/detail?id=1030009

    Try

    $ grep pae /proc/cpuinfo

    to see if you have the PAE bit set, and therefore can access
    more than about 4 GB of RAM.

    http://osdir.com/ml/admin.managers/2.../msg00042.html

    is a thread that may have some relevant information for you,
    relating to the PAE extension, which apparently the
    thread thinks is similar to the EMS extension, long ago
    (I can't say, I for one do not have it). Therefore, there
    will be a performance hit.

    >
    > Thanks.
    >
    >



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  6. Re: How much memory can a 32-bit kernel address?

    In the sacred domain of comp.os.linux.advocacy,
    Hemant Shah didnst hastily scribble thusly:

    > I have a 32-bit system with 4GB of memory.
    > How much more memory can I add to it?


    I *think* the limit is 36 gigs.
    (you need to enable PAE (paged address extension) in the kernel)
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  7. Re: How much memory can a 32-bit kernel address?

    alt wrote:
    > On Fri, 19 Oct 2007 16:47:25 +0000, Hemant Shah wrote:
    >
    >
    >> I have a 32-bit system with 4GB of memory. How much more memory can I
    >> add to it?
    >>
    >> Thanks.

    >
    >
    > I think you're at the limit. 32bits all set to one is about 4096MB (4GB)
    >


    You're forgetting PAE memory access. Allows you to do page indirect
    accesses to handle memory beyond what is allowable by straight
    access.


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

  8. Re: How much memory can a 32-bit kernel address?

    Hemant Shah wrote:
    >
    > I have a 32-bit system with 4GB of memory.
    > How much more memory can I add to it?


    On a 32-bit system any one process can only address 4 GB
    of memory. So if you mean any one process, that's it.

    But Linux supports multiple processes and virtual memory.
    You need to look in the hardware manuals for your model to
    see how much can be installed in it. So if you mean the
    hardware, you are not limited to 4 GB because you run 32
    bits.


  9. Re: How much memory can a 32-bit kernel address?

    Hemant Shah wrote:

    > I have a 32-bit system with 4GB of memory.
    > How much more memory can I add to it?


    This depends on both your hardware (RAM slots, memory management...) and
    kernel software. Usually the hardware imposes the stricter limit.

    DoDi

  10. Re: How much memory can a 32-bit kernel address?

    On Fri, 19 Oct 2007 16:47:25 +0000, Hemant Shah wrote:

    > I have a 32-bit system with 4GB of memory. How much more memory can I
    > add to it?


    64GB max on x86 with correctly configured vanilla kernel IIRC. Your
    motherboard won't go that high.

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