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

[Ivan Voras]

On 16 March 2011 21:03, Erik Trulsson <ertr1013 at student.uu.se> 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.