Cortex-A9 RealMode Memory size

Note: This was originally posted on 29th April 2011 at http://forums.arm.com

Dear ARM's guru,

I'm asking myself about the ARM real mode and especially about the memory management on this mode.

Is there a limitation on memory allocution in real-mode under ARM?
Is ARM's Cortex CPU behave like Intel's x86 CPU in real-mode in term of memory allocution?

In fact I want to know if I could use more than the usual 1Mb (Using Gate A20 trick) available in real-mode with an Intel CPU.

Many thanks in advance.
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  • Note: This was originally posted on 30th April 2011 at http://forums.arm.com

    None of the concepts you mention exist in ARM systems.

    Out of reset the memory is 4GB linear and flat mapped; with the MMU enabled, each process still has a 4GB linear address space, however, the operating system can map each 4KB to any physical address.

    The answer to your final question appears to be yes, you can [theoretically] use ~4096 times the amount.

    hth
    s.
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  • Note: This was originally posted on 30th April 2011 at http://forums.arm.com

    None of the concepts you mention exist in ARM systems.

    Out of reset the memory is 4GB linear and flat mapped; with the MMU enabled, each process still has a 4GB linear address space, however, the operating system can map each 4KB to any physical address.

    The answer to your final question appears to be yes, you can [theoretically] use ~4096 times the amount.

    hth
    s.
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