Date: Wed, 24 May 2000 08:48:00 -0700 From: Cy Schubert - ITSD Open Systems Group <Cy.Schubert@uumail.gov.bc.ca> To: Dan Nelson <dnelson@emsphone.com> Cc: Chuck Paterson <cp@bsdi.com>, arch@FreeBSD.ORG Subject: Re: Preemptive kernel on older X86 hardware Message-ID: <200005241548.e4OFmtY22468@cwsys.cwsent.com> In-Reply-To: Your message of "Wed, 24 May 2000 10:24:26 CDT." <20000524102426.A8590@dan.emsphone.com>
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In message <20000524102426.A8590@dan.emsphone.com>, Dan Nelson writes: > 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. ... and have the user select options to build a custom kernel just after install, the same way Tru64-UNIX does. > > > 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. 486's make good cheap firewalls. You'll probably see them in use for that and other roles for a lot longer than you think. Regards, Phone: (250)387-8437 Cy Schubert Fax: (250)387-5766 Team Leader, Sun/DEC Team Internet: Cy.Schubert@osg.gov.bc.ca Open Systems Group, ITSD, ISTA Province of BC To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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