svn commit: r205307 - head/sys/i386/conf

[John Baldwin]

On Thursday 18 March 2010 9:16:53 pm Xin LI wrote:
> Author: delphij
> Date: Fri Mar 19 01:16:53 2010
> New Revision: 205307
> URL: http://svn.freebsd.org/changeset/base/205307
> 
> Log:
>   SSE is enabled by default about 5 years ago so there is no point pretending
>   that we support I486 and I586 CPUs in the GENERIC kernel, users wants these
>   support would have to build a custom kernel to explicitly disable SSE
>   anyways.
>   
>   MFC after:	1 month

No, this is wrong.  Revert this.  We do _not_ unconditionally use SSE in the
kernel.  GENERIC should run just fine on a 486.  If it doesn't, that should be
fixed, but I have not seen any reports to the contrary.  In general we do not
use any floating-point / MMX / SSE instructions in the kernel as our FPU
context-saving code doesn't support it.

All the x86 world is not rack-mounted 64-bit servers.  We should not remove
support for non-686 CPUs for no good reason.  486 CPUs have cmpxchg and xadd
so are perfectly adequate.

-- 
John Baldwin