Re: User defined sections

[Daniël Mantione <daniel at deadlock dot et dot tudelft dot nl>]

Hello,

I just tried to link statically, so ld.so is not involved. That works
without problems.

Daniël

On 11 Oct 2001, Nick Clifton wrote:

> Hi Daniel,
> 
> > > Thirdly - which versions of the tools are you using ?  In particular
> > > which version of ld are you using ?
> > 
> > Nasm 0.98
> > GNU ld 2.9.5
> > ld.so 2.1.3
> 
> Ok, so you are using an old version of ld.  It would probably be a
> good idea to upgrade to the most recent release (2.11.2) although
> this will not actually fix your problem :-)
> 
> > Does it also crash on your system?
> 
> Indeed it does.  I note that if I do not use your linker script
> however, the executable runs just fine.  Why are you using a custom
> linker script anyway ?  The default one appears to work OK: 
> 
>    % gcc problem.o image.o -o prob
>    % readelf -S prob | grep custom
>    [16] .custom           PROGBITS        08049544 000544 000014 00 WAX   0   0 1
> 
> Do you need the .custom section to be located at a specific address ?
> 
> Anyway I tried adding your .custom modifications to the current
> default linker script and using that, and the linker complains with:
> 
>   ld: prob: Not enough room for program headers (allocated 6, need 7)
> 
> Which is not surprising really since your new section needs a segment
> all to itself.  It is possible to work around this by tweaking the
> linker script, but it still produces an executable that seg faults.
> 
> The problem is that your load address of 0x0 causes the section to be
> written into protected memory, which generates the seg fault.  Since
> you are running this program on a virtual memory system you are never
> going to be able to just choose an arbitrary address for your section.
> It would be much better to allow the linker to do its job, and link
> the section in at an address that it deems fit, and then set up the
> program headers appropriately.
> 
> Cheers
>         Nick
> 
>