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Re: mips multi-got error
David Daney wrote:
> Thiemo Seufer wrote:
> >David Daney wrote:
> >[snip]
> >
> >>That is not supposed to work. Multi-got linking only works if there are
> >>fewer than 8192 symbols per compilation unit (input .o to the linker).
> >>See the multi-got-1 testcase in ld/testsuite/ld-mips-elf.
> >>
> >>If you need more than 8192 symbols per compilation unit you must use
> >>-xgot for the assembler. Recent GCC versions have a -mxgot option that
> >>does the same thing for GCC.
> >
> >
> >Actually, it is supposed to work. :-) It is also a known deficiency
> >in the current assembler/linker implementation.
>
> How?
>
> The gp is set in the function prolog. If a single function references
> more got/plt entries than can be indexed with a 16 bit offset, wouldn't
> you need to either load the gp before each got access(very inefficient I
> would think) or use a 32 bit offset (somewhat inefficient)?
It doesn't need a gp load before each access, one per 16-bit addressable
GOT block would be enough. (This implies a Multi-GOT extension for
relocatable object files, probably with gp0..gpN / _gp_disp0.._gp_dispN
as per-GOT symbols.)
Thiemo