Re: BUG: bfd/elf allows only 2 PT_LOAD phdrs

[Alan Modra]

On Tue, Dec 10, 2002 at 10:55:45AM -0700, Bhavesh P. Davda wrote:
> I am also attaching a alternative patch to bfd/elf.c, since
> address@hidden, the binutils maintainer for RedHat refused to apply my
> original patch. His concern was valid: the original patch would grow the
> program headers for all elf binaries, whether or not you needed 2 or
> more PT_LOAD segments.

Unfortunately, this patch won't work either.  It's way too late to
be adjusting section layout.

Possible solutions are:
a) Add heuristics to elf.c:get_program_header_size
b) Use a custom linker script that either specifies PHDRS or allocates
   the correct space for phdrs without using SIZEOF_HDRS.
c) Implement a new linker script keyword, say EXTRA_PHDR (<number>).
d) Arrange some way to easily INCLUDE the standard linker script into
   a user script.

c) or d) are probably the nicest solutions.  For d), I'm thinking of
a user script something like this

===============
. = <base address> + SIZEOF_HEADERS + <space for extra header>
INCLUDE "*default*";
SECTIONS { <extra user sections>}
===============

The "*default*" won't do anything special at the moment, so a little
coding is required to implement this, and all default linker scripts
need modifying so that instead of using

  . = <base address> + SIZEOF_HEADERS;

they use

  . = (. == 0 ? <base address> + SIZEOF_HEADERS : .);

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre