Subject: Re: Bootloader and screen modes
To: None <>
From: Peter Bell <>
List: port-acorn32
Date: 06/09/2002 15:24:19
In message <>
          Gavan Fantom <> wrote:

> In the fastboot file we currently have:
> | Select the monitor defintion file and screenmode
> Set NetBSD$MDF ADFS::4.$.AKF85
> Set NetBSD$ScreenMode "X1024 Y768 C256"
> and later on
> loadmodefile <NetBSD$MDF>
> Set Alias$SetNetBSDMode Wimpmode <NetBSD$ScreenMode>
> SetNetBSDMode
> I have a few questions on this:
> * Why ADFS::4.$.AKF85 ?
>   There is a standard location for monitor definition files, and it's not
>   the root directory of the primary hard disc. Also I don't think we tell
>   users to copy a file to there.

Yes, this is odd - I chose to copy the mdf into !BtNetBSD itself, and
adjust the Set location accordingly.  I definitely don't want to
clutter up my root directory with mdfs.

> * Why AKF85?

Dunno, it does seem a rather strange default choice.

>   Not every RiscPC has an Acorn 17" monitor on it, and I don't think we
>   should restrict the default install to this particular monitor.
> * Why 1024x768?
>   What are the requirements for the initial screen mode? I can't do this
>   resolution on my monitor, so I've changed this locally, but I would be
>   inclined to make the default something which is likely to work on all
>   monitors, and to mention in the documentation that increasing this is
>   recommended.

What is strange here is that I use an AKF60, which *is* capable of
running at 1024x768 and, indeed, does so at the RO desktop.
Unfortunately the monitor is not capable of syncing with the NetBSD
'interpretation' of 1024x768, even when I have given it the correct
mdf.  So what happens is that the bootloader screen (with the green
border) is perfectly okay at 1024x768, but as soon as the kernel is
booted the display becomes garbled.  This is true both of the install
kernel and the full kernel from sets.  I have reverted to 800x600,
which works perfectly well.

> * Why even load a monitor definition file?
>   For an application loaded by the user this makes no sense - if a mode
>   definition file is needed, it will have already been loaded. That's part
>   of setting up a RISC OS machine to use the monitor attached to it, and I
>   see no reason to force the user to configure this twice.
>   I'm not sure whether the monitor definition file is loaded by the time
>   NetBSD boots if the fastboot stuff has been installed in !Boot, but I
>   see no reason that it couldn't be delayed until after that point if not.
> If there's no compelling reason to load a monitor definition file, I'd
> like to remove this functionality. I'd also like to change the default
> screen mode to "X640 Y480 C256".

Indeed, this would all seem very sensible.

Also, how does one go about investigating why the BSD 'interpretation'
of 1024x768 is not the same as the RO 'interpretation' even when using
exactly the same mdf.

Peter Bell -