Date: Tue, 06 May 1997 14:04:53 -0700 From: Jason Thorpe <thorpej@nas.nasa.gov> To: Steve Passe <smp@csn.net> Cc: "Jordan K. Hubbard" <jkh@time.cdrom.com>, "Jonathan M. Bresler" <jmb@freebsd.org>, hackers@freebsd.org Subject: Re: One last call for a show of hands on the ALPHA port... Message-ID: <199705062104.OAA21144@lestat.nas.nasa.gov>
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On Tue, 06 May 1997 14:31:23 -0600 Steve Passe <smp@csn.net> wrote: > does anyone know if there is a digital part equivilant to the APIC? > is there a standard for SMP with Alpha chips? if so there must be something > published which the non-digital MB manufactures refer to, or is digital > the only one to make SMP/Alpha boards? Are there even any multi-processor alpha workstations? I know of the servers... and they are very non-PC-like (although NetBSD does run on the 8200 and 8400 :-) Anyhow, the standard Alpha architecture references should describe how multiprocessor systems are supposed to behave. I'm pretty sure it's nothing like the Intel way of doing things. (Note, I say that partially because I don't know of _any_ multiprocessor alpha PC-like workstations, and the PC-like alphas are different enough from PCs in a bunch of respects, anyhow...) In general, though, if FreeBSD is going to even bother with the alpha: (1) just make it run first (you have a lot of work ahead of you, especially if you even want to consider running on the alphas that don't look like PCs) (2) change your "SMP" model... the current FreeBSD SMP code seems to be the wrong approach to me. It feels like there is a bunch of "this is a PC operating system" assumptions in code that's in sys/kern (i.e. init_smp.c). Also, the kernel isn't multi-threaded... I think you've done this backwards, because the current model will mean more work to multithread your kernel later. (3) *then* think about supporting multiple processors on other architectures. ...if you do things in the wrong order (which I think you already have, but whatever), you only end up creating more work for yourself later, which tends to lead to kludgy solutions to problems. Jason R. Thorpe thorpej@nas.nasa.gov NASA Ames Research Center Home: 408.866.1912 NAS: M/S 258-6 Work: 415.604.0935 Moffett Field, CA 94035 Pager: 415.428.6939
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