Re: How to make crosstool support for VFP software fp format?

[Dimitry Andric <dimitry at andric dot com>]

YanXT Gpsign wrote:
>     Now I wonder if I can achieve it by compiling with a compatible-configured toolchain, 
> at least vfp-softfp format-compatible toolchain...like crosstool-0.42 . Is this possible? 

It could be possible, but subtle differences between your toolchain and
MontaVista's might give other problems that are very hard to solve.  It
is simply much better to compile everything using the same toolchain.

That said, you need to make sure that your toolchain uses the same
floating point options as MontaVista's.  To see what MontaVista uses,
extract one of the .o files from libGPSEngine.a, e.g.:

arm-9tdmi-linux-gnu-ar x libGPSEngine.a AGPS.o

and then run objdump -p on it, to see what float options it uses:

arm-9tdmi-linux-gnu-objdump -p AGPS.o

You should get something like (but probably a little different):

AGPS.o:     file format elf32-littlearm
private flags = 600: [APCS-32] [VFP float format] [software FP]

The "private flags" for *your* .o files should be exactly the same as
those from the MontaVista toolchain, then they can be linked together
without any problems.

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