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Date: Fri, 3 Feb 2017 06:23:53 +1100 (EST)
From: Bruce Evans <brde@optusnet.com.au>
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To: Konstantin Belousov <kostikbel@gmail.com>
cc: Bruce Evans <brde@optusnet.com.au>, Mateusz Guzik <mjguzik@gmail.com>, 
 Mateusz Guzik <mjg@freebsd.org>, src-committers@freebsd.org, 
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Subject: Re: svn commit: r312975 - head/sys/i386/include
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On Thu, 2 Feb 2017, Konstantin Belousov wrote:

> On Fri, Feb 03, 2017 at 05:14:15AM +1100, Bruce Evans wrote:
>> You won't want to ifdef this for SMP, so the i386 implementation has
>> further bugs  like I expected (fcmpset is not implemented in the
>> CPU_DISABLE_CMPXCHG case).
>
> I think it is time to remove the option.  It certainly outlived it
> usefulness:
>
> ... VmWare 3.x seems to emulate this instruction poorly, causing
> the guest OS to run very slowly.  This problem appears to be fixed in
> VmWare 4.x, at least in version 4.5.2 ...

Yes, it is probably not useful.

Similarly for many old i386 options like NPX and SSE.  NPX might as well
be mandatory, and SSE always there but dynamically configured as it is
now.

Bruce