RFA: Skip ARM ELF Mapping symbols when showing disassembly

Andrew Cagney ac131313@redhat.com
Tue Nov 18 17:20:00 GMT 2003


> So GDB and objdump both need this information?  How does objdump handle 
>> all this?
>> 
>> - should there be a BFD method that lets GDB better identify a user 
>> visibile [minimal] symbol (gdb's elf reader currently contains what can 
>> only be described as heuristics).
>> 
>> - should there be a BFD method that, given an address and symbol table, 
>> indicates the relevant ISA/ABI?
>> 
>> - or even just have BFD export name->addr and addr->name methods?
>> 
>> Andrew
>> 
> 
> 
> The real question should be "what does gdb/objdump need to know?".  I 
> think the answer to this is that it needs to know what is at a particular 
> address in an image.  In other words, it needs to be asking "what type of 
> object is at address X?"  How that information is stored in the image is 
> not of particular interest outside of the BFD.  In particular, it 
> shouldn't matter whether the information is stored in mapping symbols or 
> some other  section in the object file.
> 
> So I think the bfd needs to export a bfd_map_address_to_type() interface 
> that hides all the details of the representation behind it.  What's less 
> clear is what types need to be returned, for ARM we really need to return 
> something like BFD_OBJECT_DATA, BFD_OBJECT_ARM or BFD_OBJECT_THUMB, but it 
> would vary from processor to processor.

It's at this point, things get weird.

BFD hands GDB a raw symbol table (ignoring coff m'kay) and then GDB 
implements the search algorithm.  To implement a addr->attrib method, 
BFD's going to need a mechanism for searching GDB's symbol table and/or 
get at the underlying bfd symbol table.

That's why I mention the third one.  Throw the whole problem back at BFD 
:-)  Why does GDB even need a minimal symbol table anyway ....

Andrew




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