Date: Fri, 26 May 2000 00:15:59 -0700 From: Cy Schubert - ITSD Open Systems Group <Cy.Schubert@uumail.gov.bc.ca> To: Peter Wemm <peter@netplex.com.au> Cc: Warner Losh <imp@village.org>, Chuck Paterson <cp@bsdi.com>, arch@FreeBSD.ORG Subject: Re: Preemptive kernel on older X86 hardware Message-ID: <200005260716.e4Q7GwR01336@cwsys.cwsent.com> In-Reply-To: Your message of "Thu, 25 May 2000 08:27:47 PDT." <20000525152747.AFBF21CE1@overcee.netplex.com.au>
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In message <20000525152747.AFBF21CE1@overcee.netplex.com.au>, Peter Wemm writes : > Warner Losh wrote: > > In message <200005241446.IAA05589@berserker.bsdi.com> Chuck Paterson writes > : > > : Once FreeBSD has a preemptive kernel FreeBSD will only run on > > : Pentium or better X86 processors. > > > > This is likely unacceptible in the embedded market. We're using > > boards with a UP 486 133's on them (actually AMDs, but you get the > > idea). We need some way to build kernels for these boxes. It sure > > would be nice, but isn't required, to have the same kernel for pentium > > UP machines. > > While I think we need to be able to support 386 and 486 still, I'm moderately > sure that we could get away with de-supporting those in GENERIC for 5.0+, > assuming that it buys us something. > > I would not have too much trouble with a proposal that a I386_CPU and > maybe I486_CPU becoming mutually exclusive with the 586+ stuff. ie: if you > will still be able to build a kernel specifically to run on a 486, but by > default it would not fly. > > I think 586+ is a convenient boundary because I am not aware of many 586's > that don't have PNPBIOS support, while 486's are mixed as they predate win95 > by a fair way. > > Aiming for a default fresh-install target (remember, 5.0 is 6-12 months > away) where we require minimum 586+ and PNPBIOS etc etc would simplify > things a fair bit.. In such a scenario it should still be possible to > build a kernel to specifically support an i486 on a non-PNP isa-only system > without PCI etc. I have a 486 still running and would hate to loose it for > sentimental reasons, but I do custom builds for it anyway. I strongly doubt > that there will be many *fresh* 486 installs, if any at all. 486's make good cheap firewalls and in one case I use a 486 as an Xserver/testbed. If a component breaks, no fuss, just replace the whole box. I'd hate to lose the ability to do a fresh install on a 486 or re-install for DRP reasons. A procedure for the user building a boot/install floppy for 486 systems from source (on a 586/686) or supplying a 386/486-only boot floppy on the CDROM would be a good compromise. With the lack of PNPBIOS in this case, since 386/486 machines are simpler, a manual configuration manually using visual configuration mode would also be acceptable -- if you're not sure what's inside a 486 machine, you probably won't have the skill to configure tune the kernel to run on it anyhow. > > But that is changing the subject. :-) > > > I would have no problem saying SMP is only supported on Pentiums or > > newer. > > I don't think we support 486 SMP right now, but I could be wrong. I think that not supporting 486 SMP is much of an issue. The only 486 SMP boxes I've worked on were NCR 3600's running NCR AT&T SYSV R4.2, about the size of a fridge. 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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