svn commit: r205307 - head/sys/i386/conf
John Baldwin
jhb at freebsd.org
Fri Mar 19 12:00:05 UTC 2010
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
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