MIPS gas/ld -xgot handling is broken for at least mips*-linux

[David Daney]

Thiemo Seufer wrote:
> Hello All,
> 
> since the introduction of multi-got in the mips gas/ld the -xgot
> option breaks in ld as soon as the GOT size grows over the
> (single-GOT) 64 kB limit. ld tries to handle it as multi-GOT
> instead of a large single GOT.
> 
> I see two approaches to fix this:
> - Disallow the -xgot option for traditional mips. The appended patch
>   does so. This will leave SGI-style configurations broken. On IRIX,
>   this would imply using the native ld.
> - Let ld handle xgot compiled code as large single GOT again. For this,
>   it needs either some xgot flag, or has to generally disable multi-GOT
>   for SGI-style configurations. The elf header provides a EF_MIPS_XGOT
>   flag, but this isn't set by gas yet.
> 
> I tend to do the first because I don't know if xgot ever really
> worked on linux. Comments?
> 

On mipsel-linux (and the untested mips-linux configuration):

The java support in gcc-3.4.x and beyond currently uses the compiler's
-mxgot flag which generates large got code via explicit relocs.

Earlier private versions of this support for gcc-3.3 use the gas -xgot
option.

We are forced to do this (I think) due to the screwed up way that
libtool generates the libgcj.so shared library (piece-wise linking due
to command line length restrictions).

I have not observed any problems doing this with binutils 2.15 (perhaps
I am lucky).

So if there is really a problem in ld with large got support, I would
rather see it fixed rather than disallow large gots.

I believe that other libraries may also use -xgot due to the same
libtool issues (KDE or Gnome IIRC).

David Daney.