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PADDING execution regions

Vijaya Kumar
Note: This was originally posted on 24th February 2010 at http://forums.arm.com

Dear All,

   I am looking for RVDS 2.2 arm linker option where I can pad the execution region with 0xFF's so that the size of the execution region is aligned to 4KB.

I have tried to use

EXEC 0x2000 PADVALUE 0xFFFFFFFFFF 0x1000
{
  x.ptl(RO);
}

But the unused EXEC region is not padded with 0xFF's in the output image.
  • Note: This was originally posted on 25th February 2010 at http://forums.arm.com

    The PADVAULE option specifies what value to use for padding - it does not cause more padding to be added.

    So if all the input sections are removed by the linker (by redundanct section elimination), the execution region will be empty.

    What are you trying to achieve?


    Thanks for your reply.

    I have created execution regions with valid data (RO  data) which is not aligned with 4KB size. I want the execution region to be padded with 0xFF's  to be 4KB aligned size, so that loading the execution region is efficient in case I dynamically load the execution region (Demand Paging).

    ex: if the actual size of execution region is 0x900 bytes, I want linker to pad the execution region by 0x700 bytes in the binary image generated.
  • Arm Employee Badge
    Note: This was originally posted on 25th February 2010 at http://forums.arm.com

    You will need to specify the --no_legacyalign option on the armlink command line. By default the linker assumes it can use 4 bytes alignment without padding, and then "unpack" the binary when running it for the first time. For demand paging this is obviously not what you want.
  • Arm Employee Badge
    Note: This was originally posted on 24th February 2010 at http://forums.arm.com

    The PADVAULE option specifies what value to use for padding - it does not cause more padding to be added.

    So if all the input sections are removed by the linker (by redundanct section elimination), the execution region will be empty.

    What are you trying to achieve?