[Bug 861296] Re: mmap fails to allocate 2030Mb heap on ARM

[Dr. David Alan Gilbert]

This is an artefact of a different in where the libraries are mapped on
the two architectures.

On ARM we have;
   executable
   heap
                        <---- ~1GB
   libs
                        <---- ~3GB
  stack            


So there isn't one big 2GB chunk to allocate.

On x86 they have:
   executable
   heap
                       <--- ~3GB
   libs
   
I don't know why ARM does it this way however and whether it's changeable.

Dave

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https://bugs.launchpad.net/bugs/861296

Title:
  mmap fails to allocate 2030Mb heap on ARM

Status in Linaro Toolchain Miscellanies:
  New
Status in “eglibc” package in Ubuntu:
  New

Bug description:
  The attached testcase pass on ia32 but fails on armel systems running oneiric.
  test system got 512mb of ram and 3Gb of swap.

  gcc mmap-test.c -o mmap-test
  ./mmap-test

  on my pandaboard I hit Couldn't allocate the heap: 2025Mb
  on my ac100 I hit Couldn't allocate the heap: 2027Mb

  The testcase fails to allocate heap on armel in the range of
  2023-2030Mb and above.

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