Date: Wed, 24 May 2000 10:24:26 -0500 From: Dan Nelson <dnelson@emsphone.com> To: Chuck Paterson <cp@bsdi.com> Cc: arch@FreeBSD.ORG Subject: Re: Preemptive kernel on older X86 hardware Message-ID: <20000524102426.A8590@dan.emsphone.com> In-Reply-To: <200005241446.IAA05589@berserker.bsdi.com>; from "Chuck Paterson" on Wed May 24 08:46:03 GMT 2000 References: <200005241446.IAA05589@berserker.bsdi.com>
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In the last episode (May 24), Chuck Paterson said: > The 386 processors do not support the locked exchange instruction. > For these systems the locked exchange can be replaced with roughly a > "cli, tst, cmp, branch, store, sti". > > The following are the obvious choices > > 1. Make two separate builds. Why not just make it conditional on the "cpu I386_CPU" line in the kernel Makefile? The comment already reads: # deleting the specification for CPUs you don't need to use may make # parts of the system run faster. This is especially true removing # I386_CPU. Distribute GENERIC just like usual, and let the user remove I386_CPU when he builds his own kerenl. > I have talked to a couple of people who think that supporting this > older stuff won't be important to FreeBSD by the time the kernel is > preemptive. Some even thought supporting the original Pentium > processors might not be required. I'll propose the following as it I wouldn't go that far, unless you're thinking 3-4 years in the future? There are a lot of overdrive and AMD CPUs out there that use the 486 instruction set. -- Dan Nelson dnelson@emsphone.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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