Date: Thu, 25 May 2000 13:37:23 -0700 (PDT) From: "Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net> To: chad@DCFinc.com Cc: vallo@matti.ee, msmith@FreeBSD.ORG, steve@sse0691.bri.hp.com, stable@FreeBSD.ORG Subject: Re: 4-stable won't boot Message-ID: <200005252037.NAA70216@gndrsh.dnsmgr.net> In-Reply-To: <200005251840.LAA29149@freeway.dcfinc.com> from "Chad R. Larson" at "May 25, 2000 11:40:48 am"
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> > > Did you take all of them out at once? The AUTO_EOI options are BAD and > > > EVIL and we should _not_ be letting people use them. > > > > Then please document it in the LINT, I remember that on the first time I > > did custom kernel those EOI options seemed quite useful to include in > > kernel config. After a while following the lists they didn't seem so... > > As with most things, absolutes are rare. > > My kernel config files on my 2.2.x systems have contained > > options "AUTO_EOI_1" > options "AUTO_EOI_2" > > for ever, without problem. > > What makes that e-vile? Early versions of the 8259 (pre A version) and clones that copied that broken design. See Lint for some details: # AUTO_EOI_1 enables the `automatic EOI' feature for the master 8259A # interrupt controller. This saves about 0.7-1.25 usec for each interrupt. # This option breaks suspend/resume on some portables. # # AUTO_EOI_2 enables the `automatic EOI' feature for the slave 8259A # interrupt controller. This saves about 0.7-1.25 usec for each interrupt. # Automatic EOI is documented not to work for for the slave with the # original i8259A, but it works for some clones and some integrated # versions. I've seen lots of modern hardware that works fine with AUTO_EOI_1, but I don't dare turn ont AUTO_EOI_2 unless you like to crash and burn. It is probably possible, but non-trivial, to write code that can detect if the 8259 does AUTO EOI correctly and disable this if it doesn't. But like I said, non-trivial. -- Rod Grimes - KD7CAX @ CN85sl - (RWG25) rgrimes@gndrsh.dnsmgr.net To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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