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    SubjectRe: 4Gb ram not showing up


    Satyam Sharma wrote:
    > On 6/6/07, Lennart Sorensen <lsorense@csclub.uwaterloo.ca> wrote:
    >> [...]
    >> A better description would be:
    >>
    >> "Select this if you have a 32-bit processor and memory mapped in the 1GB
    >> to 4GB address range."
    >> [...]
    >> That one would be better as:
    >>
    >> "Select this if you have a 32-bit processor and ram mapped in the
    >> address
    >> range above 4GB."
    >
    > Ugh, no! How can we expect the user compiling a kernel to be *so*
    > familiar with address space re-mapping / BIOSen (_his_ particular
    > BIOS, specifically, and what / how it re-maps memory) / etc to be
    > able to answer such questions? "Select ... if you have ... RAM
    > installed" is perfectly clear, simple, and all that's needed.
    >
    However the KConfig help message as it is currently written is wrong.
    > BTW, just imagine what a user would need to do to make things
    > work as per your proposal. Build some kernel (don't care about
    > memory loss), boot and find what his firmware prefers to do with
    > address space (or else read up the BIOS documentation!) and
    > _then_ again build a new kernel, this time selecting the options
    > appropriately ...
    I tried to do this, but the Kconfig help message was misleading. I
    still needed to come here for help.
    >
    > Also, note that the change you're proposing is unnecessary! As
    > Andi pointed out, this issue has more to do with broken BIOSen
    > and the proper fix for Tom is to contact his vendor and flash /
    > upgrade the BIOS firmware. I don't see anything wrong with the
    > Kconfig help texts.
    Andi was wrong. It appears that he read the first sentence of my email
    and jumped to a conclusion. The /proc/mtrr output that I included in my
    first post showed the my bios was doing the right thing. My problem was
    that I was using CONFIG_HIGHMEM4G, which is what the KConfig help
    message told me to do. After switching to CONFIG_HIGHMEM64G the OS was
    able to map all of my ram.

    total used free shared buffers cached
    Mem: 4016768 3924312 92456 0 360132 3030336
    -/+ buffers/cache: 533844 3482924
    Swap: 5116692 2676 5114016

    Thanks to those with the correct advice. I'm sure I would have got this
    by trying each memory model in turn, but at least now I know what is
    going on.

    Tom

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