Date: Wed, 27 Sep 2000 20:55:08 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: brett@lariat.org (Brett Glass) Cc: 1mazda1@phoenixdsl.com (1mazda1), bright@wintelcom.net (Alfred Perlstein), chat@FreeBSD.ORG, advocacy@FreeBSD.ORG Subject: Re: Pulse poll at Borland Message-ID: <200009272055.NAA25048@usr02.primenet.com> In-Reply-To: <4.3.2.7.2.20000927111427.048114f0@localhost> from "Brett Glass" at Sep 27, 2000 11:20:37 AM
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> >> Yep. Believe it or not, I even have a BeBox in the lab. > > > >> --Brett > > > >WHY??????????? > > It holds the door open. ;-) > > Seriously, it's actually a pretty spiffy machine, with > its Wurlizer-style jukebox LEDs and all. I'd run NetBSD on > it if they could get SMP working, but right now I'd waste > half the CPU if I didn't keep BeOS on it. The BeBox will probably never run an SMP BSD, because BSD SMP work is tied too tightly to the MESI cache coherency model. The dual PPC 603 BeBox cheats. Since the 603 does not have the signal lines for an IPI based cache invalidation or update, the MMU was omitted from the BeBox, and the MMU control lines used to implement SMP capability. In practice, this means that the machine is somewhat slower than it needs to be (by one bus wait cycle per invalidation event), and that it uses an MEI model, not an MESI model. BSD SMP does not have the synchronization points necessary to cope with the additional explicit invalidations required in MEI in order to maintain interprocessor state coherency. PS: FWIW, I'm the one who lobbied JLG, successfully, to release the BeBox programming specifications needed to get a non-Be OS on the thing. It's a damn shame that they quit building the hardware. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message
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