ELF LOAD segments creating holes in the process image on GNU/Linux

[H.J. Lu]

On Mon, Jan 3, 2022 at 4:31 AM Florian Weimer via Binutils
<binutils@sourceware.org> wrote:
>
> At least on x86-64 on GNU/Linux, for PIE and non-PIE binaries, LOAD
> segments are not always contiguous.  The triggering conditions are not
> quite clear to me.
>
> For ET_EXEC (non-PIE) executables, I think this is a supported feature,
> and the kernel and glibc dynamic loader handle this the same way,
> creating holes.  However, these holes make dealing with the main
> executable slightly more complicated in some cases (e.g., we can handle
> contiguous mapping slightly more efficiently when looking objects based
> on addresses).  Holes also make page tables less compact (although that
> effect is probably minuscule).  Abstractly, I don't see a reason why the
> link editor has to create such holes on the most common targets.  (I
> have heard that ia64 really needed those holes.)
>
> For ET_DYN (PIE) executables, we have a Linux vs glibc difference: The
> Linux loader creates holes as well, while the glibc loader refuses to
> create them and fills them with a PROT_NONE mapping from the executable.
>
> Is this something we could fix in ld?
>

Is it created by -z separate-code?

-- 
H.J.