[Query] Re: dwarf unwinder (only works on i386/x86_64)

[Roland McGrath]

> The original choice for using debug_frame was because it was always
> available (since we required debuginfo already) and it was complete. GCC
> 4.4 changed this though (and the uprobes_ustack.exp test does indeed
> fail when build with gcc 4.4). [...]

To be fair, 4.4 only changed one of the many wrinkles that fold together
here.  It was never really the case that either one was always complete
when present.  (It's a big hairy subject.)