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Date: Mon, 18 Aug 1997 11:29:31 -0500
From: Jonathan Lemon <jlemon@americantv.com>
To: =?iso-8859-1?Q?S=F8ren_Schmidt?= <sos@sos.freebsd.dk>
Cc: Greg Lehey <grog@lemis.com>, jkh@time.cdrom.com,
        msmith@atrad.adelaide.edu.au, hackers@FreeBSD.ORG
Subject: Re: reset screen hardware?
References: <19970817163116.16698@lemis.com> <199708170951.LAA00412@sos.freebsd.dk>
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On Aug 08, 1997 at 11:51:19AM +0200, Søren Schmidt wrote:
> So to get concrete in this matter, we need:
> 
> 1. Being able to call realmode code from the kernel.
> 
> 2. Being able to run BIOS functions, that is we need to keep
>    track of the BIOS's workspace, most often in low memory.
> 
> 3. Then write the code to call the right BIOS functions to 
>    be able to talk to the video HW.
> 
> So, if someone is SERIOUS about getting this to work, pick one
> of the above, come back to me so we can get technical about
> the details, and them submit the diffs. Then I'm certain it will
> be committed, and the author will get his fair share of applause..

Well, I'm working on it.  I've posted the results of a proof-of-concept
implementation to -emulation, but still have to finish working out all
the bugs out of the implementation.

Right now, the code can call any random BIOS interrupt for which there is
an interrupt vector in low memory.  Calling random realmode routines will
be equally easy.  This is currently done from usermode for debugging, but
can also easily be done from the kernel.

Right now, what I'm working out is:

	- how to manage a process that doesn't have a valid 32-bit user
	  context, but needs to be able to process interrupts.

	- how to serialize access to the BIOS, given that there probably
	  need to be some pre/post processing of memory data areas.

	- whether to allocate more data area than 0-4K and isadevbase-1M.
--
Jonathan