[ECOS] i386 FPU (was: RE: [ECOS] need help getting started with eCos for Intel 386EX!!)

[ECOS] i386 FPU (was: RE: [ECOS] need help getting started with eCos for Intel 386EX!!)

[Fabrice Gautier]

> -----Original Message-----
> From: Bart Veer [ mailto:bartv@redhat.com ]
> Sent: Friday, October 13, 2000 5:48 AM
> To: mkruger@ziton.com
> Cc: ecos-discuss@sourceware.cygnus.com
> Subject: Re: [ECOS] need help getting started with eCos for Intel
> 386EX!!
> 
> 
> I remember seeing some 386-specific code in the PC port, relating to
> floating point units and the like. I do not know how extensive the
> support is, you would have to look at the x86 HAL's for more
> information. 

About this code relating to the FPU, there is some kernel function call here
so Redboot won't compile - I had to remove that part. 
Anyway is the FPU necessary ? I think some cpu (some arm) don't have FPU so
at least I think it should be an option.

Regards

-- 
Fabrice Gautier
fabrice_gautier@sdesigns.com 

Re: [ECOS] i386 FPU (was: RE: [ECOS] need help getting started with eCos for Intel 386EX!!)

[Bart Veer]

>>>>> "Fabrice" == Fabrice Gautier <Fabrice_Gautier@sdesigns.com> writes:

    >> -----Original Message-----
    >> From: Bart Veer [ mailto:bartv@redhat.com ]
    >> Sent: Friday, October 13, 2000 5:48 AM
    >> To: mkruger@ziton.com
    >> Cc: ecos-discuss@sourceware.cygnus.com
    >> Subject: Re: [ECOS] need help getting started with eCos for Intel
    >> 386EX!!
    >> 
    >> I remember seeing some 386-specific code in the PC port,
    >> relating to floating point units and the like. I do not know
    >> how extensive the support is, you would have to look at the x86
    >> HAL's for more information.

    Fabrice> About this code relating to the FPU, there is some kernel
    Fabrice> function call here so Redboot won't compile - I had to
    Fabrice> remove that part. Anyway is the FPU necessary ? I think
    Fabrice> some cpu (some arm) don't have FPU so at least I think it
    Fabrice> should be an option.

eCos has no dependency on a hardware FPU. If the target processor does
not have an FPU then typically eCos will provide software emulation
instead. Even if there is an FPU the appropriate HAL may provide a
configuration option to disable support in case the application has
no need for floating point, which can help to cut down context switch
times etc.

I have not looked at the 386 code in any detail so I do not know
exactly what goes on in there. It is very possible that more work is
needed.

Bart Veer // eCos net maintainer