How to remove i387 from the system?

Joel Sherrill joel.sherrill at OARcorp.com
Mon Apr 17 20:16:41 UTC 2000



Stream Labs wrote:
> 
> Hello All,
> 
> I have a working RTEMS application for pc486 target and want to run it on a
> simplified i386 machine. What should I do to remove 387 coprocessor from the
> system, which is
> lacking here, to do it in the most correct way.
> 
> Thank you, best regards,  Ivan Romanov. <STREAM.L at g23.relcom.ru>

It depends on what precisely you mean.  If you mean physically remove
the FPU
from the PC, then (unless you are using an i486SX) you can't do this.

If you mean what software steps are needed to generate code that can run
on an i386 family cpu w/o FPU, then you will need to add a pc386_nofp
configuration as an alias for the pc386.  See pc486/pc586 for examples.
Turn on -msoft-float in the pc386_nofp CPU_CFLAGS.

Which brings us right back to the previous post and how i386 users
need to work with the gcc maintainers to get the floating i386 soft
float patch working.  

If you don't use float operations, this is great.  If you do, then you
will need to link against a library providing these operations.  No such
library is provided with gcc for the i386 (the softfloat fuctionality 
is there for other CPUs).  

-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
Support Available                (256) 722-9985



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