Date: Thu, 06 Dec 2001 19:34:12 +0000 From: Ian Dowse <iedowse@maths.tcd.ie> To: John Baldwin <jhb@FreeBSD.org> Cc: Dmitry Konyshev <daemon@agava.com>, freebsd-hackers@FreeBSD.org Subject: Re: switching to real mode Message-ID: <200112061934.aa63585@salmon.maths.tcd.ie> In-Reply-To: Your message of "Thu, 06 Dec 2001 09:24:58 PST." <XFMail.011206092458.jhb@FreeBSD.org>
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In message <XFMail.011206092458.jhb@FreeBSD.org>, John Baldwin writes: >The short form is htat you need to hack the cpu_halt to call a function that >puts a stub down in low memory, and calls it. This code needs to be mapped 1:1 >so that the logical address == physical address. The first thing you will Yeah, I attempted something like this a few years ago without much success. I've just updated the code to compile on -stable, and it seems to half-work in that it appears to successfully switch to real mode and clear the screen using the video BIOS, but then it just hangs. That's pretty close to what I remember it doing originally, although I think it might have worked before the VM86 stuff was enabled by default in FreeBSD. Getting this sort of code to work reliably is almost impossible... Source is at http://www.maths.tcd.ie/~iedowse/FreeBSD/diskboot/ (loading the resulting KLD immediately shuts down to real mode). Ian To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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