Re: [arm-gnu] urgent toolchain

[Carlos O'Donell <carlos@xxxxxxxxxxxxxxxx>]

Charles Manning wrote:
> On Tuesday 19 August 2008 02:39:52 Carlos O'Donell wrote:
> > The run-time may contain VFP instructions as long as they are never
> > executed on hardware that does not have a VFP.
> Won't executing an FP instruction on non-FP hardware just raise an illegal 
> instruction exception allowing an exception handler to do software FP if this 
> is set up?
That's not how it's done.

On a GNU/Linux target the kernel advertises, at process startup, the 
hardware capabilities via the AT_HWCAP entry in the auxv vector.
The ARM GNU/Linux userspace can check to see if HWCAP_ARM_VFP is 
enabled, and then set the variable no_vfp accordingly.
If the kernel can emulate a VFP, then the kernel will set HWCAP_ARM_VFP, 
and userspace will try to use VFP instructions, otherwise it should not.
Cheers,
Carlos.
--
Carlos O'Donell
CodeSourcery
carlos@xxxxxxxxxxxxxxxx
(650) 331-3385 x716