Re: Need help debugging arm application.
On 5/21/09, Lennart Sorensen <lsorense@csclub.uwaterloo.ca> wrote:
> I thought part of EABI was the ability to use both hardware and software
> FPU efficiently. Isn't that the case? Or is the FPU on that particular
> arm just not supported?
It allows linking of softfloat and hardfloat code, which previously
was impossible. Debian armel packages and libraries are compiled to
use softfloat so they work on all hardware, but to make use of an FPU
you have to recompile stuff from source telling GCC to generate real
FP instructions. You can then link this code with the standard
softfloat libraries. I only know of one package, liboil, that detects
the presence of a VFP FPU at runtime, which seems to be what you are
suggesting. It explicitly has two sets of code and selects between
them at runtime after inspecting /proc/cpuinfo.
In the case of this FPU, the Cirrus Logic MaverickCrunch, the support
in standard GCC for it has never generated correct code for it, and
there are a slew of hardware timing bugs to work round, hence the need
for a modified compiler.
M
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