Date: Thu, 17 Jul 1997 02:10:46 -0600 From: Steve Passe <smp@csn.net> To: cbrown@aracnet.com Cc: smp@FreeBSD.ORG Subject: Re: HEADS UP: EISA cards. Message-ID: <199707170810.CAA12815@Ilsa.StevesCafe.com> In-Reply-To: Your message of "Thu, 17 Jul 1997 00:13:59 -0800." <33CDD447.25F5C25B@earthling.net>
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Hi, >And which SMP machines do not have a APIC? Maybe I should have made >myself more clear. Why not abandon the 8254 completely when in >Full symmetric mode. You have to do a bunch of stuff when >you switch modes, so why not add this to it. The answer is that we haven't studied the issue well enough to make a decision as to what we should do for timer services. Having a central timer that is not tied to any particular CPU has advantages also. Among these is the possibility for any available CPU to handle its INTerrupt. Given our limited resources, alot of design decisions go along the lines of "what needs doing next, and what can we put off for awhile" as oppossed to a commercial operation where the decision is instead "who can we assign this task to?". The bottom line here is that we can probably get along with the 8254 timer and existing code for quite awhile, while we can forsee no need to the EISA DMA chaining. And going to the APIC timers will be a fair amount of time & code to achieve. -- Steve Passe | powered by smp@csn.net | Symmetric MultiProcessor FreeBSD
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