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

Bjoern A. Zeeb bzeeb-lists at
Thu Mar 17 09:10:47 UTC 2011

On Wed, 16 Mar 2011, Julian Elischer wrote:

> 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 around.
> I believe you can now get a 486 core in some arrays.

You mean something like this .. though it's not a fully classic?  It's
one of the soekris boxes I boot/run as long as I manage to get a
kernel and a world in an mdimage booted from tftp... yes you can still
get down to that tiny size though there's a lot of ignorance for that
in our tree these days.

CPU: AMD Enhanced Am486DX4/Am5x86 Write-Back (486-class CPU)
   Origin = "AuthenticAMD"  Id = 0x494  Stepping = 4
real memory  = 33554432 (32 MB)


Bjoern A. Zeeb                                 You have to have visions!
          Stop bit received. Insert coin for new address family.

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