glibc: loading of shared objects with holes wastes address space

[Mathias Krause]

On Tue, Oct 18, 2011 at 3:44 PM, Ian Lance Taylor <iant@google.com> wrote:
> Mathias Krause <minipli@googlemail.com> writes:
>
>> I see. So the real problem are the holes themselves. If there wouldn't
>> be any gap between two adjacent segments, then there would be no need
>> to stuff them. And honestly, currently those holes are not needed at
>> all. Neither the glibc nor the kernel seem to honor the alignment
>> requirements when searching for a suitable address. So the question
>> is: Why are the sections in the linker script aligned to MAXPAGESIZE
>> instead of PAGESIZE, i.e. aligned to 2 MiB instead of 4 KiB? But it
>> looks like this is more of a question for the binutils folks (CCed).
>
> Because then the executable will still run on some hypothetical future
> kernel that uses larger page sizes.

Are there _any_ plans from Intel/AMD (or rumors, even) to drop the
page size support for 4 KiB pages in a future x86-64 based
architecture? At least, I'm not aware of such a thing. So this can not
really be an argument for choosing 2 MiB for ELF segment alignment.

Mathias