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Path: sserve!manuel.anu.edu.au!munnari.oz.au!news.hawaii.edu!ames!sun-barr!cs.utexas.edu!sdd.hp.com!think.com!enterpoop.mit.edu!eff!ssd.intel.com!ichips!hfglobe!imutm1.de.intel.com!gold.sub.org!jonas.gold.sub.org!rommel From: rommel@jonas.gold.sub.org (Kai Uwe Rommel) Newsgroups: comp.unix.bsd Subject: Re: [386BSD] 16550 Not Resetting. Distribution: world Message-ID: <723329963rommel.root@jonas.gold.sub.org> Sender: root@jonas.gold.sub.org Date: Wed, 02 Dec 92 21:59:23 MET References: <1992Nov28.115716.8219@runx.oz.au> <CGD.92Nov28202543@eden.CS.Berkeley.EDU> <1992Nov30.131213.18948@runx.oz.au> Organization: Private Lines: 27 In article <1992Nov30.131213.18948@runx.oz.au> bde@runx.oz.au (Bruce Evans) writes: >Blame the hardware. After the software has put the h/w in a weird state, >it is often too difficult, and sometimes impossible, to recover without a >full h/w reset. Yet the h/w doesn't provide any (standard?) way to force >a h/w reset from s/w. 386BSD shuts down by causing a triple fault. My >understanding is that this doesn't reset the h/w, it just shuts down the >cpu, then on most systems the motherboard h/w detects the shutdown and >causes some sort of reset. I wonder why the reset isn't full? Perhaps >so that it can be used to switch 286's out of protected mode. >-- >Bruce Evans (bde@runx.oz.au) To cause a reset, some ports in the keyboard controller could be used, that was the way to reset the machine back in the AT's days. However, although that caused a full POST with memory check etc., it may also still not cause a full H/W bus reset (one could look up this in the AT tech ref.?). Kai Uwe Rommel -- /* Kai Uwe Rommel Muenchen, Germany * * rommel@jonas.gold.sub.org Phone +49 89 723 4101 * * rommel@informatik.tu-muenchen.de Fax +49 89 723 7889 */ DOS ... is still a real mode only non-reentrant interrupt handler, and always will be. -Russell Williams