Re: Darwin multilibs

[Michael Meissner <meissner@the-meissners.org>]

On Tue, May 27, 2003 at 01:09:30PM -0700, Dara Hazeghi wrote:
> > It's not silly at all... if you had to save FP
> > context at every 
> > interrupt, the kernel would be a lot slower.
> 
> Thanks for the point. You're the second one to point
> out this fact to me! I guess it just seems strange to
> me because I'm used to x86/Linux, which has no
> multilibs (that I'm aware of)...

Due to the 'crippled' nature of the x86 floating point stack, and the fact that
the xmm registers are only in the newer chips and aren't enabled unless you
specifically say to use them, you aren't likely to run into the condition where
you would need to use the -msoft-float option.  If it was likely that the
register allocator would allocate a floating point register, then the kernel
would presumably need to use a switch that disables the floating point
registers just like it does on the Alpha, SH, SPARC, PARISC Linux kernels.  In
the early days (on 386sx processors), it might have been advantageous to use
-msoft-float if glibc had ever been multilib'ed.

-- 
Michael Meissner
email: meissner@the-meissners.org
http://www.the-meissners.org