Re: ARM ABI calling conventions

[Mark Wielaard <mjw at redhat dot com>]

On Fri, Dec 02, 2011 at 12:35:43PM -0700, Wade Farnsworth wrote:
> Yes, in theory the ABI calling conventions can differ between kernel
> and user space as well as between individual user space binaries.
> [...]
> I expect most distributions have switched to EABI by now, though it
> wouldn't surprise me if there was some legacy code running somewhere
> that uses OABI.
> 
> Would it be possible to support both ABIs, parsing the ELF header to
> obtain the flag and then take the appropriate action?

I guess it would be possible. But I expect nobody uses OABI anymore
for real. Or at least not for those systems that also want to support
systemtap on ARM. Let me make my request more precise:

a) Is there anybody out there using systemtap on ARM using OABI?
b) If so, would you be willing to help out making sure systemtap
   supports both OABI and EABI?

Note that this is only for things like direct register.stp argument
fetching. For dwarf based accesses things should be fine. It is also
just for integral types, since systemtap doesn't support floating
point atm. So different hard/soft float variants of the base EABI
are not something we need to deal with.

I don't mind supporting more than just base EABI, but it would be nice
to hear of anybody actually using something else these days. Especially
since I will be unable to test it myself.

Thanks,

Mark