How to make crosstool support for VFP software fp format?

YanXT by_yanxt@gpsign.com
Mon Dec 11 16:31:00 GMT 2006


 2006-12-11一的 11:19 +0100,Dimitry Andric wrote:
> 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]

you were right, the command I put for testing:

[YanXT@R51:~/sirfapi061030](0)$ arm-9tdmi-linux-gnu-objdump -p AGPS.o

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

just like what u said. :)
 
and I tested one lib under crosstool dir, the result was as follows:

[YanXT@R51:/opt/crosstool/gcc-3.4.1-glibc-2.3.3/arm-9tdmi-linux-gnu/arm-9tdmi-linux-gnu/lib](0)$ arm-9tdmi-linux-gnu-objdump -p libm.so|grep private
private flags = 202: [APCS-32] [FPA float format] [software FP] [has
entry point]

Ah, so , obviously, their software FP format don't match, 
beside compiling libGPSEngine with my rebuilt toochain which supports
FPA, How can I build crosstool to have VFP softwaredefault float format
support? 

thanks~ 

YanXT




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