Multilib support for 68040

Aaron J. Grier
Tue Jan 22 12:05:00 GMT 2002

On Mon, Jan 21, 2002 at 12:26:18PM -0800, Glynn Smith wrote:
> I am using gcc 2.95.2 configured as a Cross m68k compiler hosted on
> PPC-LINUX.  The standard multi-lib support seems to be for 68000 68020
> 68881 & soft-float.  

and cpu32 and m5200.  :)

> Question 1
> Can this version or a later version of the GCC compiler be configured
> so that it generates a 68040 multilib branch uses only floating point
> instruction from the set of instructions that are supported by the
> 68040 FPCP and does NOT emulate the unsupported instructions using

according to the documentation for 2.95.2, yes:

     Generate output for a 68040.  This is the default when the
     compiler is configured for 68040-based systems.

     This option inhibits the use of 68881/68882 instructions that have
     to be emulated by software on the 68040.  Use this option if your
     68040 does not have code to emulate those instructions.

> Question 2
> Motorola FPCPs have the option of setting them up so that the floating
> point precession is embedded in each floating point instruction rather
> that setting the precession in the FPCR (Control register) before each
> operation.  Is there a compiler flag to enable this option?

I have no idea.  have you disassembled code to see what the compiler
default is?

  Aaron J. Grier  |   Frye Electronics, Tigard, OR   |
     "In a few thousand years people will be scratching their heads
       wondering how on earth the first computer was invented and
          bootstrapped without a prior computer to do it with."
                    --  Chris Malcolm, on comp.arch

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