Re: Intel x86 Kernel Console irregularity

Riley Williams (rhw@BigFoot.Com)
Fri, 6 Aug 1999 17:26:50 +0100 (GMT)


Hi Tom.

> I know this doesn't happen very often but:-

> If the BIOS (or Boot ROM) leaves the screen not in the normal
> 80x25 text mode (in my case the screen was in 80x50 mode) then
> when the kernel boots it thinks the screen only has 25 lines so
> will scroll at line 25 rather than 50. The console is then
> totally messed up and no amount of setfont will rectify the
> situation. With the first few lines displaying not in the
> viewable screen area and ncurses programs complaining about
> invalid coordinates.

I'm not sure what the problem with your setup is, but I have three
systems that start up in non-80x25 modes, and ALL of them correctly
scroll at full screen and use its full width without any problems.

For reference, my P166 boots into 80x50 mode, my 486 laptop boots into
80x60 mode and my K6-2 boots into 128x43 mode, and the kernel
correctly deals with all three of them.

The P166 and 486 have been using those screen sizes since 2.0.33 was
current. I didn't get the K6-2 until recently, but it's run with those
dimensions under RedHat's 2.2.5-15 and 2.2.5-22 kernels as well as
under raw compiled 2.2.6, 2.2.9 and 2.2.10 kernels. I would therefore
have to assume that suchlike support is not a recent invention...

> Perhaps it would be good if the kernel specifically sets the
> screen mode into a known state before booting.

As far as I can tell, it already does. In fact, the only time I've had
any problems was when I'd previously run a script that ran the command
`stty rows 25 columns 80` irrespective of what the screen dimensions
were, and I then ran `screen` - the result was, to put it politely, a
mess...

Best wishes from Riley.

+----------------------------------------------------------------------+
| There is something frustrating about the quality and speed of Linux |
| development, ie., the quality is too high and the speed is too high, |
| in other words, I can implement this XXXX feature, but I bet someone |
| else has already done so and is just about to release their patch. |
+----------------------------------------------------------------------+
* ftp://ftp.MemAlpha.cx/pub/rhw/Linux
* http://www.MemAlpha.cx/kernel.versions.html

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