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Patch from Charles Gauthier <Charles.Gauthier@…> to address
FP issues on this target:
The default variants of libc, libm and libgcc assume that a 68881
coprocessor is present. Without the FPSP, any floating point operation,
including printf() with a "%f" format specifier, is likely to cause an
unimplemented instruction exception.
The FPSP works with the default variants of libc, libm and libgcc. It does not
work in conjunction with the msoft-float variants. The paranoia test goes into
an infinite loop at milestone 40. I am guessing that floor() is returning an
incorrect value.
The msoft-float variants of libc, libm and libgcc appear to do floating point
I/O properly. They only failed in paranoia. Offhand, I can't think of why they
would conflict with the FPSP, so I think that there is something wrong with the
msoft-float code. It might be my installation.
Given my experiences, I decided to install the FPSP in bsp_start(), and to link
against the default variants of libc, libm and libgcc. This causes the
executables to increase in size by about 60 KB. The README file and the
mvme167.cfg specify how to remove the FPSP, and how to link against the
msoft-float variants of the libraries. This is not what Eric Norum had done: on
my host, his gen68360_040 port links RTEMS code with the msoft-float variants
of libc and libm, and the default variant of libgcc. In this configuration, the
output of printf() with "%f" is garbage on my target.
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