Date: Mon, 10 Nov 1997 03:58:12 -0600 From: Tony Overfield <tony@dell.com> To: Terry Lambert <tlambert@primenet.com>, mike@smith.net.au (Mike Smith) Cc: mini@d198-232.uoregon.edu, hackers@FreeBSD.ORG Subject: Re: x86 gods; advice? Suggestions? Message-ID: <3.0.3.32.19971110035812.00701028@bugs.us.dell.com> In-Reply-To: <199711091021.DAA24289@usr06.primenet.com> References: <199711080954.UAA00629@word.smith.net.au>
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At 10:21 AM 11/9/97 +0000, Terry Lambert wrote: [Tremendous amounts of nine-fingered vm86 task creation and operational ideas deleted] >This sort of answers Tony Overfield's "3. Something else..." question: >you can get a Task Gate Descriptor in the LDT or GDT or IDT. This means >"Something else..." can be triggered by: Uh no. Let's see if we can follow the thread.... [Here, it's clear that Terry and Tony aren't on the same page. :-( ] In reference to bootloader ideas, and referring to calling the real-mode BIOS calls from the kernel initialization code, Tony asked: > Speaking of vm86(), why not just use real-mode? It's easier and much > better for compatibility while booting. In response, Mike asked (rhetorically, I think) how one could load the kernel into memory without using protected mode at all: >How do you copy the kernel into memory > 1M in real mode? If you could >elaborate on this (and how to *stay* in real mode while running over >1M, ie. so that the kzip pass and subsequent real-mode startup >requirements could be met), I'd be *very*happy* [Here, it's clear that Mike and Tony weren't on the same page. :-( ] Terry's suggestion to load the kernel into memory without using protected mode at all is this: >There are several ways to do this. The main one uses a call that drops >into protected mode, changes a 64k mapping at the top of the 1M >you can get at, and goes back to protected mode. [Here, it's clear that Terry and Mike weren't on the same page. :-( ] Wondered which of the possible "real-mode" only approaches Terry was thinking about, I said: >I can't tell, but I think you're talking about one of these: > >1. ... switching to protected mode, setting larger segment limits > and then switching back to real mode. > >2. ... the real mode trick of using FFFF:xxxx addressing. > >3. Something else. [Here, it's clear that Tony and Terry weren't on the same page. :-( ] So there we are. Terry misunderstood the question asked by Mike who misunderstood the question asked by Tony, who probably asked an ambiguous question to begin with. Sorry. I *never* have this problem with people I already know. Dang this "language" stuff we're forced to use to communicate. ;-/ - Tony
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