--- In "charliem_1216" <> wrote:
>
> --- In "j.chitte" <j.chitte@> wrote:
> >
> > --- In "j.chitte" <j.chitte@> wrote:
> > >
> > > Hi,
> > >
> > > I have build a working 2.6.29 kernel using Matthieu's patchset. It was
> > > built with old abi compatibility.
> > >
> > > I don't think I should have any old abi stuff floating about now so I
> > > wanted to rebuild it eabi only since this should be more effiecient.
> > >
> > > However , when I disabled OABI_COMPAT the floating point menu gets
> > > disabled. I just see:
> > > *** At least one emulation must be selected ***
> > >
> > > Does this make sense or is it a glitch in kconfig :?
>
> I think it is a glitch, and hasn't been updated for the eabi-only case.
>
> > >
> > > TIA.
> > >
> >
> > Ah!
> > Depends on: !AEABI || OABI_COMPAT
> >
> > So does that mean I have to rely on using Maverick in order to run eabi
> > only?
>
> No, maverick is completely separate. Remember, the kernel uses no FP at all;
> what you are configuring here is which FPU emulator to build into the kernel.
>
>
> OABI needs an emulator in the kernel, since userspace FP is done by the
> kernel trapping & emulating hardfloat instructions. That's what makes
> floating point under OABI so slow. EABI doesn't need an emulator because
> userspace programs use softfloat (no illegal instruction trapping & emulation
> needed).
>
> If you configure AEAB and OABI_COMPAT, then you still have to include a FPU
> choice in the kernel (for the OABI side).
>
> regards, ......... Charlie
>
> >
> > Help says I must have some sort of FPE even if there is an FPU.
> >
> > thx
> >
>
OK, I get it. So the recent compiler's softfloat option gets around the need
for emulation in the kernel.
So as long as I am building with softfloat enabled , which is known at this
stage, the kconfig would seem to be correct except for displaying that one of
the no longer accessible options is needed.
The message is wrong but the config is valid. That was much of the confusion.
Many thanks for clarifying what is going on.
Could you clarify one point about Maverick. I can enable it in the kernel but
as long as I'm building with softfloat rather than hardfloat toolchain this
would seem contradictory.
What would be the result of such a set up?
thx
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