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Date:      Fri, 27 Sep 1996 21:46:45 +1000 (EST)
From:      Julian Assange <proff@suburbia.net>
To:        sos@freebsd.org
Cc:        hackers@freebsd.org
Subject:   Re: SVGATextMode under FBSD
Message-ID:  <199609271146.VAA07741@suburbia.net>
In-Reply-To: <199609271118.NAA29653@ra.dkuug.dk> from "sos@FreeBSD.org" at Sep 27, 96 01:18:21 pm

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> > But one has to tell syscons what resolution one desires. Presently,
> > there is no way to do this in any granular manner. (i.e one must
> > choose from a small number of predefined definitions)
> 
> Erhm, what do you mean by that ?? There is no way of making this
> totally dynamic ??

If you are bypassing conventions and programming the chipset
directly, then you can impliment any text resolution you like,
limited only by the dot clock and the memory on your video card.
This is how I am able to run 170x60x(8x16 font) under linux.
syscons needs hooks so one can define how many rows/cols the
video hardware is using.

> No, its tightly coubled with a given piece of video hardware, and
> support should be loaded after it has been found out which one it is,
> or you will get _*HUGE*_ kernels...

This isn't what I meant. I plan to foster most of the code out to
user land, as is done in XF86 and SVGATextMode. The kernel
changes required to permit the userland code to tell syscons that
it needs to physically re-size its character memory.

> > At the moment, I've just started on the hair pulling. Following the vga
> > VBLANK/SYNC registers in order to work out clock timings, seems to have
> > problems. The nasty thing is, if you don't do it quick enough the isa
> > interrupt system dies and the kernel panicks. Makes using gdb to walk
> > through that code real fun. Evidently XF86 manages to do it however.
> > SVGATextMode is by and large stolen XF86 code, I suspect with the
> > #ifdef __FreeBSD__'s removed.
> 
> Why do you want to do this ?? the 4 noramlly selectable clocks are
> pretty std (and mostly of no use :)), In order to use the REALLY
> interesting dot clocks you must know the board & chipset, and then
> you know the timings as well....

Right. SVGATextMode XF86 derived code knows all the chipsets and sometimes
the clocks. However, a given chipset may have different clocks or clock
generators within different versions of itself, this is why you may need
to probe. e.g X -probeonly. I could probably bypass that code, and still
have something that would work, though it would take more configuration
on behalf of the user. However I'd like to have it do everything the linux
version does, which is really just what XF86 does, but for text. SMOP

-- 
"Of all tyrannies a tyranny sincerely  exercised for the good of its victims  
 may be the most  oppressive.  It may be better to live under  robber barons  
 than  under  omnipotent  moral busybodies,  The robber baron's  cruelty may  
 sometimes sleep,  his cupidity may at some point be satiated; but those who  
 torment us for own good  will torment us  without end,  for they do so with 
 the approval of their own conscience."    -   C.S. Lewis, _God in the Dock_ 
+---------------------+--------------------+----------------------------------+
|Julian Assange RSO   | PO Box 2031 BARKER | Secret Analytic Guy Union        |
|proff@suburbia.net   | VIC 3122 AUSTRALIA | finger for PGP key hash ID =     |
|proff@gnu.ai.mit.edu | FAX +61-3-98199066 | 0619737CCC143F6DEA73E27378933690 |
+---------------------+--------------------+----------------------------------+



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