r343567 aka PAE vs non-PAE merge breaks i386 freebsd

[Rodney W. Grimes]

> On Thu, Feb 28, 2019 at 12:46 PM John Baldwin <jhb at freebsd.org> wrote:
> 
> > On 2/28/19 11:14 AM, Cy Schubert wrote:
> > > On February 28, 2019 11:06:46 AM PST, Conrad Meyer <cem at freebsd.org>
> > wrote:
> > >> On Thu, Feb 28, 2019 at 10:32 AM Steve Kargl
> > >> <sgk at troutmask.apl.washington.edu> wrote:
> > >>> This is interesting as well.  Does this mean that amd64 is now
> > >>> the only tier 1 platform and all other architectures are after
> > >>> thoughts?
> > >>
> > >> This has been the de facto truth for years.  i386 is mostly only
> > >> supported by virtue of sharing code with amd64.  There are efforts to
> > >> promote arm64 to Tier 1, but it isn't there yet.  Power8+ might be
> > >> another good alternative Tier 1 candidate eventually.  None have
> > >> anything like the developer popularity that amd64 enjoys.
> > >>
> > >> Conrad
> > >> _______________________________________________
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> > >
> > > We deprecated and removed support for 386 and 486 processors. We should
> > consider removing support for low end Pentium as well. I'm specifically
> > thinking of removing the workarounds like F00F. Are there any processors
> > that are still vulnerable to this?
> >
> > We have only removed support for 386 since it didn't support cmpxchg.  We
> > still
> > nominally support 486s.  I don't know how well FreeBSD 13 would run on a
> > 486, but
> > in theory the code is still there and the binaries shouldn't die with
> > illegal
> > instruction faults.
> >
> 
> The biggest barrier to running on a real 486 is that it's hard for FreeBSD
> to fit into 32MB that was the maximum config you could have. You can barely
> boot it w/o tuning, though it will still fit a few jobs if you are looking
> at something super low-end with a lot of effort.

Effort that has been completed in several places, wifi-build for one,
where I did boot a 12.0 image of 8MB in size running in 32MB iirc on
a D-Link DIR-855? router.

> There are a few later CPUs built on basically a 486 whose chipsets could
> support up to 128MB or 256MB which is enough to run FreeBSD still.

Amd Geode would be in that group?

-- 
Rod Grimes                                                 rgrimes at freebsd.org