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Date:      Sat, 25 Jan 2003 22:53:51 +1100
From:      Peter Jeremy <peterjeremy@optushome.com.au>
To:        Rodolphe Ortalo <ortalo@laas.fr>
Cc:        arch@FreeBSD.ORG
Subject:   Re: the mythical syscons redesign document ( was Re: Porting wscons )
Message-ID:  <20030125115351.GA21347@cirb503493.alcatel.com.au>
In-Reply-To: <Pine.LNX.4.21.0301242229490.489-100000@tempest.rod.fr>
References:  <20030123234431.GB555@athlon.pn.xcllnt.net> <Pine.LNX.4.21.0301242229490.489-100000@tempest.rod.fr>

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On Fri, Jan 24, 2003 at 10:58:12PM +0100, Rodolphe Ortalo wrote:
>I understand clearly why doing so may be important for serial consoles (or
>possibly other non-display adapters), but wrt most (modern) VGA adapters,
>I have the feeling that discarding the state and switching to some
>advanced mode should be done as soon as possible! :-)

I'd prefer to retain state if at all possible.  It's very useful being
able to look back through the kernel output - whilst working on the
TGA driver, I found it quite annoying that the main TGA device probe
would wipe all the state.  (This is also something I find particularly
irritating about sysinstall - the probe messages are all wiped by the
sysinstall menu so you don't know if the hardware was found correctly).

Personally, I don't see why it's at all important to switch out of
text mode quickly.  Kernel output messages are inherently text so
switching to a graphics mode just makes more work for the kernel.
I know Sun have had their logo in the boot screen for as long as I
can recall - and it's getting fancier with time - but I fail to see
that this is more than unnecessary frippery.

> Note that this does not necessarily mean discarding VGA-style display
>mode; but for example if the board allows to access all needed VGA
>registers via a MMIO area (instead of the usual fixed adresses regs around
>0x3C0) and its framebuffer (including the VGA part) via another area,

Whilst I can't verify it, I believe Tru64 does something like this.
It's quite obvious that the text font on a VGA card changes when the
card is probed during the main device tree scan.  Presumably the card
is being switched to a graphics mode by the main device driver.

>difficult to share) VGA adresses in a multiple-boards configuration are
>cleared, and further initialisations of remaining boards can proceed more 
>cleanly.

How common is this?  And how important is it that both cards function
during boot?  I have two Matrox Millennium-II cards in one of my
systems and I'm not at all fazed by one of them not being initialised
until X starts.  I suspect that very few people have more than one
graphics adapter and even fewer want to be able to use both adapters
outside X.

Peter

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