Subject: Re: default built kernels and com4
To: None <>
From: Mike Long <>
List: current-users
Date: 04/14/1994 15:03:48
>Date: Thu, 14 Apr 1994 13:15:22 -0400
>From: Ken Hornstein <kenh@wrl.EPI.COM>

>I was thinking; maybe all that is necessary is to restore the value of
>0x2ea after the probe routine zeros it.  Wouldn't that fix the screen blank
>problem, and make everyone happy?  I'd try it out, but I'm not at current yet.
>Anyone else want to try this?

I never meant to imply that the write of zero to 0x2ea was the only
problem.  The com driver stomps all over several other 8514A registers
in the 0x2e8 to 0x2ef region, as well.  I haven't fully investigated
exactly what happens, but we know the final results:  Endless reboot
cyles and blank screens.

Either the com driver probe routine has to be altered to look out for
the presence of 8514A compatible video (which may not be possible
and/or not desirable), or support for COM4 in the generic configs has
to be removed.  I find it hard to believe that it is more difficult to
swap your modem to COM[1-3], as opposed to trying to use a system that
can't successfully boot a generic kernel AT ALL because of this

I'm willing to email the 8514A register desription from VGADOC3.ZIP to
anyone who wants to look at it, or post it to the list if enough
people want it.  The whole thing is ~31K, 668 lines.  The portion that
covers 0x2e8 to 0x2ef is smaller.
Mike Long                               
VLSI Design Engineer                              voice: (617)461-4030
Analog Devices, SPD Div.                            FAX: (617)461-3010
Norwood, MA 02062                            *this = !opinion(Analog);