Date: Fri, 12 May 95 12:05:23 MDT From: terry@cs.weber.edu (Terry Lambert) To: rgrimes@gndrsh.aac.dev.com (Rodney W. Grimes) Cc: seki@sysrap.cs.fujitsu.co.jp, FreeBSD-Hackers@FreeBSD.org Subject: Re: Questions/comments on ed driver Message-ID: <9505121805.AA02282@cs.weber.edu> In-Reply-To: <199505121744.KAA01158@gndrsh.aac.dev.com> from "Rodney W. Grimes" at May 12, 95 10:44:19 am
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> > 2. When put into 16 bit operation (isa16bit is on), if_ed.c turns the > > interface in 16 bit mode just before data transfer, and then back in 8 > > bit mode everytime. The comment says it makes DOS reboot process > > happy, but, if so, why cannot the back-in-8-bit process be done only > > in kdc_shutdown() hook? > > What happens if you panic while the system is running and the board is > in 16 bit mode? The system would fail to reboot :-(. > > The problem is that on some machines, if you leave the board in 16-bit > mode, will hang during the BIOS boot. I think the comment should be > correted to say that, or both BIOS/DOS. > > This one is not a bug. Maybe it should be a compile time option (defaulted "on" for the kernels that are prebuilt) that if turned off would only do the switch in the shutdown. I don't know what the performance difference would end up being. The same argument about protecting for reboot *could* be used to justify reinstating the A20 stuff prior to stuffing the keyboard reset, since it would make some currently unhappy systems more happy ( cv: "The Undocumented PC"). Terry Lambert terry@cs.weber.edu --- Any opinions in this posting are my own and not those of my present or previous employers.
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