svn commit: r219679 - head/sys/i386/include

Julian Elischer julian at
Thu Mar 17 05:00:33 UTC 2011

On 3/16/11 2:16 PM, Ivan Voras wrote:
> On 16 March 2011 21:03, Erik Trulsson<ertr1013 at>  wrote:
>> On Wed, Mar 16, 2011 at 06:45:53PM +0100, Roman Divacky wrote:
>>> On Wed, Mar 16, 2011 at 12:32:56PM -0400, Jung-uk Kim wrote:
>>>> On Tuesday 15 March 2011 08:45 pm, Maxim Dounin wrote:
>>>>> This isn't really different as long as GENERIC kernel used, as
>>>>> GENERIC defines I486_CPU.
>>>> Fixed in r219698, sorry.
>>>> Actually, I think we should remove i486 from GENERIC at some point.
>>>> It has too many limitations.  For example, I really love to implement
>>>> atomic 64-bit mem read/write using cmpxchg8b (no 0xf00f joke, please)
>>>> but I cannot do that cleanly without removing I486 support or
>>>> checking cpu_class at run-time. :-(
>>> if we drop i486 I think it makes sense to require something that has
>>> at least SSE2, thus we can have the same expectations as on amd64.
>> No, that would remove support from far too many machines that people
>> actually use to run FreeBSD.
>> There are probably only a handful of people (if that) who actually run
>> FreeBSD on an actual 486-class machine, but requiring SSE2 would mean
>> dropping support for Pentium-III and Athlon-XP equipped machines and
>> I believe there are a large number of such machines still in use, and
>> they are still perfectly suitable for a large number of tasks.
> This is understandable but I also think it deserves a poll at stable@
> and current at . It might be worth keeping i486 for all of 9-stable but
> removing it before 10-stable. Judging from previous releases, 9.x
> would be supported until at least 2016. I don't follow the embedded
> world that much, but from what I saw, most (incl. Soekris) are moving
> to Atom designs which support SSE2.

not sure what is in the Soekris and other embedded machines but do 
keep them in mind.

many are now 586 class I guess but there may still be some 486 ones 
I believe you can now get a 486 core in some arrays.


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