Newsgroups: comp.os.minix
Subject: Re: VGA/Graphics Driver
References: <87de2b$arm$1@nnrp1.deja.com> <6s3dr9h4ml.fsf@iago.nac.net> <kEGm4.12$p01.736@bgtnsc05-news.ops.worldnet.att.net> <6swvok2mtj.fsf@iago.nac.net> <57pg78.r8e.ln@jetsam.cs.vu.nl>
From: Mark Gray <markgray@iago.nac.net>
Date: 05 Feb 2000 04:51:26 -0500
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kjb=732035@cs.vu.nl (Kees J Bot) writes:
> In article <6swvok2mtj.fsf@iago.nac.net>,
> Mark Gray  <markgray@iago.nac.net> wrote:
> >"Tony" <tony@my.isp> writes:
> >
> >> So does this mean that it's useless in protected mode?
> >
> >No -- the kernel can call the bios -- see /usr/src/kernel/bios_wini.c
> >for an example.  (You would have to hack the kernel to give you a hook
> >to access it is all.)
> 
> The 2.0.2 BIOS interface should allow one to make any kind of BIOS call.
> One thing that isn't shown in the bios_wini.c and dosfile.c drivers is
> that you can also call a vector (is that what you mean by a "hook"?):

No, by a hook I meant a system call that a usermode program could use.
(I assumed he did not want to do all his vga work in kernel mode.)

> 	reg86.b.intno = 0;	/* Signals use of a vector. */
> 	reg86.w.off = offset;
> 	reg86.w.seg = segment;	/* segment:offset is the vector. */
> 	... set regs ...
> 	level0(int86);

> I can't remember testing this.  Sometimes you code things for
> completeness, but you have no need to use or test the extra
> functionality.  :-)

I will probably be giving it a test before summer for a minix project
I am planning to work on -- thanks for the information.
