Specifying Segment Attributes

[Daniel Jacobowitz]

On Mon, Aug 29, 2005 at 12:25:22PM -0700, Prasad Venkata Boddupalli wrote:
> Hello,
> 
> I am writing a loader for a multi-threaded processor in which multiple
> instances of an application run on different threads. Multiple
> instances, besides their data segments mapped to a different physical
> location also have a shared memory. The loader needs to recognize this
> shared segment in the elf-executable. From the elf specification and the
> linker script command language, I realized that one of the ways of
> specifying the segment attribute as 'shared' is to use the 'PHDRS' command
> and specify the attribute as part of the 'flags' of that segment.
> 
> Is there any other way as the use of PHDRS command will force one to
> describe all segments ?

Not without changing the linker.

>From something I sent to Ian last week, off list, so increment the
"third":

> This is the third time in the last couple of weeks that I've felt we                                  
> needed a mechanism to add an additional program header explicitly:                                    
> give it a name, add one to the number estimated by SIZEOF_HEADERS,                                    
> allow sections to be assigned to it... do you think it could be                                       
> feasibly implemented?  I haven't looked at the magic behind                                           
> SIZEOF_HEADERS.                                                                                       
>                                                                                                       
> But making folks define PHDRS manually when they really just want to                                  
> extend it is a real nuisance.                                                                         

Ian made some other suggestions, that I'll let him share if he wants
to, but I'm still attached to mine :-)

-- 
Daniel Jacobowitz
CodeSourcery, LLC