documentation for augmentations in .eh_frame?

[David Mosberger]

Is there any documentation (other than the source-code) that describes
the augmentations used in the .eh_frame section?  Between DWARF3 and
LSB v1.3, I found a description of most everything else related to
stack unwinding, but the augmentations don't seem to be documented
anywhere.  Or am I missing something?

A related question: it appears to me that the "text base" (tbase) in
the DWARF2 unwinder could only ever be non-zero if
__register_frame_info() gets called (which, I believe won't be the
case on "modern" systems).  Is this correct?

Thanks,

	--david