RFC: SH4 and the __fpscr_values object

[Daniel Jacobowitz <drow at mvista dot com>]

Due to the way that the SH4 FPU operates, we have to save two values for the
control register (one for single precision and one for double precision) in
a global state so that we can switch between single and double precision
operation without losing changes to the fpscr state.  That's my memory of
how it works, anyway.

What it boils down to is that any application which uses the FPU needs to
have a copy of __fpscr_values, and it's important that there be exactly one
copy in the application; including all loaded libraries.

For a while this was implemented by having it in crti.o; it's since moved to
crt1.o (don't know exactly why).  The problem is that there's now an
undefined reference in libm to __fpscr_values, and we build libm using -z
defs.

So, any ideas on the right way to solve this problem?  Is there some reason
I'm missing that it can't just be a normal variable in libc6?  That won't
fix any libraries which build with -z defs but don't link to -lc, but I
don't think there are many examples of that.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer