atom feed7 messages in org.freebsd.freebsd-platformsRe: To share or not share ? (was: Som...
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John S. DysonMar 17, 1997 10:00 pm 
John BirrellMar 17, 1997 10:38 pm 
Pedro GiffuniMar 18, 1997 12:09 am 
Terry LambertMar 18, 1997 9:46 am 
Terry LambertMar 18, 1997 9:51 am 
Terry LambertMar 18, 1997 4:41 pm 
Pedro GiffuniMar 18, 1997 6:25 pm 
Subject:Re: To share or not share ? (was: Someone working on a SPARC version?)
From:John S. Dyson (to@dyson.iquest.net)
Date:Mar 17, 1997 10:00:13 pm
List:org.freebsd.freebsd-platforms

The VM, as John Dyson has pointed out in the past, is not irretrievably architecture specific. I don't believe there is a technical issue at all... I have had FreeBSD's VM code working on Alpha and, more recently, PPC hardware, with only minor changes.

I have also heard that, it is not 386 specific, but rather "FreeBSD specific", you're right, but I haven't heard of anyone using FreeBSD's VM under NetBSD (did you?).

It is true that the interfaces in the VM system have changed (and are therefore FreeBSD specific), but those interfaces are part of the improvements associated with the VM code. Changing the interfaces isn't all that difficult, and the hardest part about a port of the VM code is likely the pmap module changes. One really bad thing about the original VM code is that the pmap code is called lots and lots of times. We have mitigated that significantly.

Frankly, it is likely that a VM system that performs as well as the FreeBSD VM code (and I am not making any relative claims here -- the other *BSDs are making some improvements), is going to require interface changes relative to the original Lite/2 code.

John