x86 boot code build

[Garrett Cooper]

On Fri, Oct 5, 2012 at 12:08 AM, Dag-Erling Smørgrav <des at des.no> wrote:
> Konstantin Belousov <kostikbel at gmail.com> writes:
>> Dag-Erling Smørgrav <des at des.no> writes:
>> > Dimitry Andric <dimitry at andric.com> writes:
>> > > Well, do we still officially support any real i386 machines?
>> > No, 486 and up only.  Personally, I think we should ship 586
>> > binaries (pentium-mmx) by default.
>> There is absolutely no architectural difference between usermode ISA
>> between i386 and pentiums, ignoring SMP-support instructions, which
>> are usually not emited by the compiler anyway.
>
> By "binaries" I mean ISOs and freebsd-update, including the kernel.
>
> (actually, it's the kernel I care the most about)
>
>> Really interesting stuff started appearing with pentium pro, like CMOV
>> instructions. Even more important, -march=pentiumpro generates much
>> better -fPIC code (probably could be activated by -mcpu=pentiumpro).
>
> Which is why most Linux distributions target 686, but we can't if we
> want to support small systems like the AMD Geode-based soekris net4xxx
> and net5xxx out of the box.

     I would target the appropriate architecture (amd64) where it
matters (amd64), and target the lowest sane common denominator on
i386. In reality, what does a couple MB mean on amd64 vs i386?
Thanks,
-Garrett