I486_CPU or I586_CPU in kernel config

Adam Vande More amvandemore at gmail.com
Tue May 31 00:39:57 UTC 2011

On Mon, May 30, 2011 at 6:53 PM, Warren Block <wblock at wonkity.com> wrote:

> sys/i386/i386/support.s is mentioned, but doesn't seem to have anything
> explicitly specific for 586.  There are some i686 entries.
> A test for cpu_class==CPUCLASS_586 in /sys/i386/isa/npx.c is mentioned in
> the thread, but that check isn't in the current code.

Yeah, there doesn't seem to be concrete answer that's within my ability to
diagnose.  If you have some time and the burning desire, you could try some
benchmark runs on each kernel to see if 686 is as preformant as 686/586.
The first thread I posted seemed indicate a fairly noticeable slowdown when
both were enabled, but there were perhaps problems with test methodology and
of course that is quite old.

Also seems like a good candidate question for hackers@

Adam Vande More

More information about the freebsd-questions mailing list