[bitlug] Re: ELF??

  • From: Pavan Chandrashekar - Sun Microsystems <Pavan.Chandrashekar@xxxxxxx>
  • To: bitlug@xxxxxxxxxxxxx
  • Date: Wed, 09 Nov 2005 13:06:50 +0530

Any body else interested in ELF stuff?? using it perhaps??

Interested?? In using ELF?? Oh..., should i say just *yes*? Bread and butter man, as boss says :-) [pun intended]

DSP is binary, objcopy does that in a trice... but I need to know what the compiler has done to create the object file, and modify that for my architecture...

Ok. First of all, what do you use to build the ELF that you want to dump onto the DSP? A cross compiler I suppose. And *no* shared objects, I presume, unless you have some kind of Virtual MM on that DSP system you are talking about.

Do you want to know how the object file (.o) is created or the executable - static or shared?

Plain relocatable object files are created by the assembler with the help of opcodes for instructions and the addressing formats that are used for accessing data, and of course the data itself. Refer Instruction formats for concerned architectures. How these contents are placed into corresponding sections is something that is extremely compiler specific.

For example, remember .rodata? GCC prevents the writing of data in this section. The solaris CC also has the .rodata, but allows writing to data in here.

Archives(.a) are created (using ar) by bundling the symbol information from all the relocatable objects that are part of the archive into a symbol table.

Shared objects are something that i am not very much aware of (ironically). However, the usage of symbols whose definitions are in shared objects need the runtime linker to manipulate the references to point to the right definitions, at runtime.

And, just to be correct on the terminology, all these are done by the link editor (ld).


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