Re: RFA: Recording MIPS ABI selection in binaries

[Andrew Cagney <ac131313 at cygnus dot com>]

Michael Eager wrote:
> 
> One of the action items I have on my plate for the Dwarf2
> committee is to write/revise a proposal for handling multiple
> architectures within a single compilation/executable.  My
> current thinking is that this would be handled by an extension
> to the line number information.  This would permit fine
> grained specification of the ISA.  (One motivation for this
> is for a processor which can switch between ISA's in the
> middle of an assembly file.)

Rather than line number information, would it be easier to just mark
sections using special symbols?  objdump could then at least understand
it.

Apparently the ARM toolchain is already doing this to differentiate
between arm and thumb modes.

> I may not have followed this thread as well as I might have.
> Is the question w/r/t MIPS about identifying MIPS 3 vs MIPS 4
> ISAs, or distinguishing between 32-bit and 16-bit ISAs.  The
> latter is (unfortunately) encoded in the low order bit of the
> target address of a jump, and cannot easily be determined by
> looking at the object file.

The original patch proposed the addition of a note section so that GDB
could identify a specific ABI.  From there it went to the general
problem of where should ISA/ABI information really reside in an object
file.

Given GDB can now use this information, a correct home for it is needed.

	enjoy,
		Andrew