allocate apecified memory location for a c variable

This is a discussion on allocate apecified memory location for a c variable within the Linux Programming forums, part of the Platform Specific Boards category; Is there any function to allocate memory at a given virtual address to a c/c++ variable ? I have tried ...

  1. #1
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    allocate apecified memory location for a c variable

    Is there any function to allocate memory at a given virtual address to a c/c++ variable ?

    I have tried using mmap with flag MAP_FIXED for the same but it gives me a segmentation fault when I run it.

  2. #2
    Deathray Engineer MacGyver's Avatar
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    I believe it's compiler specific to get a variable to be at a specific address. Consult your compiler's documentation or perform a google search for this type of stuff.

    I know it's been discussed on the forums before, so you might want to search the forums here.

  3. #3
    Massively Single Player AverageSoftware's Avatar
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    In C++, this can be done with placement new.

    Not sure about plain C.

    Addendum:
    Hmm, looking again at the way you phrased it, this probably isn't what you want. Sorry.
    Last edited by AverageSoftware; 06-01-2007 at 06:01 AM.

  4. #4
    Cat without Hat CornedBee's Avatar
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    Sounds exactly like what he wants. Of course, he first needs to make sure he can use the memory at that virtual address, e.g. by using mmap with MAP_FIXED.

    You might also want to look into the Boost.Shmem library.
    All the buzzt!
    CornedBee

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    and the hat of wrongness Salem's Avatar
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    Is there anything to be gained by doing this in a virtual address space?
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  6. #6
    Cat without Hat CornedBee's Avatar
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    Yes. If several processes use shared memory or a shared mmapped file at the same virtual address, pointers into the memory are valid in both processes.
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

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