> The change consists of installing a dwarf2_frame_set_init_reg
> callback that overrides the default register state initializtion
> to instead perform the following: set all call-saved registers to 
> DWARF2_FRAME_REG_SAME_VALUE, all call-clobbered registers to
> DWARF2_FRAME_REG_UNDEFINED, and the virtual PC register to
> DWARF2_FRAME_REG_RA.  Which registers count as call-saved vs.
> call-clobbered is defined by the Linux for S/390 and Linux for
> zSeries ABI documents.

Ok, I've committed the attached.

Andrew