Re: [PATCH 2 of 2] cc/gcc: 4.4.5, add arm-softfloat-libgcc patch from buildroot

["Yann E. MORIN" <yann dot morin dot 1998 at anciens dot enib dot fr>]

Bryan, Khem, All,

On Saturday 13 November 2010 19:09:18 Bryan Hundven wrote:
> > The patch is needed for a toolchain configured with old ABI (oabi) and
> > soft float
> > as old abi is stale and obsolete upstream gcc has no interest in this
> > patch. that said
> > you dont need it if you do not build oabi toolchains. Most of stuff
> > these days use eabi
> > and eabi toolchains dont require it. Does ct-ng supprt oabi toolchains ?

Yes, crostool-NG still has the ability to build OABI toolchains.
I know that OABI is deprecated, but there are still systems out
there that use OABI, and for which upgrading to EABI is simply
not feasible.

> It may be interesting to know now if Michel's ctng config had eabi turned 
> off.

The tuple for Michael's toolchain was arm-cortexa8-linux-gnu which means
it is OABI.

> I know that eabi is a boolean option, that defaults to 'y', but can be disabled.
> So I would assume that oabi is still possible with crosstool-ng.

Yes.

> I have a question about the "-lfloat" in the gcc/config/arm/linux-elf.h.
> I thought that libfloat was provided by the netwinder floating point
> emulation, but on modern (gcc > 4.1) toolchains, I don't see any
> reference to libfloat except in gcc/config/arm/linux-elf.h. Am I
> missing something?

Googling for "netwinder floating point emulation" gives:
  http://netwinder.osuosl.org/users/s/scottb/public_html/notes/FP-Notes-all.html

Which sends us to:
  http://www.eecs.berkeley.edu/~jhauser/arithmetic/softfloat.html
which is now 404.

Anyway, the latest release of the SoftFloat library was release 2b, dating
back to May 2002:
  http://www.jhauser.us/arithmetic/SoftFloat.html

For my part, I wonder why gcc still has reference to -lfloat, when there are
available softfloat functions bundled with gcc. Are we not supposed to use
them? If so, why are they present in the first place? Well...

Regards,
Yann E. MORIN.

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