Re: Why all glibc2 programs are FPU programs
Adam J. Richter (adam@yggdrasil.com)
Tue, 26 May 1998 12:00:10 -0700
One problem with the approach of adding an AT_LINUX_FPUCW
symbol is that there can be only group of ELF executables that do
not need to execute a floating point instruction at initialization.
If you change the default FPU control word value, then all of the
old programs become floating point programs. On the other hand,
if you make the default FPU control word part of the semantic of
executable personality number, then non-FPU programs remain non-FPU
programs. Adding a separate system call to set the default FPU
control word would have this effect too, although that does add
another system call to the beginning of every program, and you
may want to retroactively change the default FPU control word
for a particular personality type if some bits turn out to have
been selected in error.
Although nobody is expecting to change the default FPU
control word or to find an error in the selection of the FPU
control word in any port that could be fixed by this mechanism,
it would be nice to be able to be prepared for that eventuality,
especially when you consider that doing so involves less work that
implementing the AT_LINUX_FPUCW symbol.
Adam J. Richter __ ______________ 4880 Stevens Creek Blvd, Suite 205
adam@yggdrasil.com \ / San Jose, California 95129-1034
+1 408 261-6630 | g g d r a s i l United States of America
fax +1 408 261-6631 "Free Software For The Rest Of Us."
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