In article <m0t6m4T-00007uC@waux11.wau.mis.ah.nl> leo@ahwau.ahold.nl writes:
>> The only thing TOS does, is to read the root sector (sector 0),
>> calculate a checksum, and (if the checksum matches some magic
>> number) execute the root setor code at offset 0. Everything
>> else is left to this root sector code.

This is true on every Atari system.  But there is a rule for deciding
from which device the boot sector is chosen.  I think it's like this:

   1. If it's a reboot, test the device that the last boot was from
   2. If 1 fails, try the floppy on A:
   3. If 2 fails, try the first SCSI device [TT/Falcon]
   4. If 3 fails, try the first ACSI device

>I understood that also the partition id played a role in this.
>I assumed this true because volker said there were bit's in the
>NV ram that determined wich id was chosen
>    - first bootable
>    - first bootable GEM/XGM
>    - first bootable UNX

I guess this is only valid on TTs, I don't know about the Falcon.

>auto-boot. The problem is that people who want to run both NetBSD
>and ASV or Linux (when they create a bootloader), will have a problem.

I think this is a little too much worry!  

>Or one could say that they should stick to TOS-boot.

That's what I'd suggest.

>> (The boot code in ROM can only handle harddisks with a 512 bytes
>>  sector size, so we don't have to worry about different sector
>>  sizes and can happily use the DMAread() XBIOS function.)

We can also use keyboard input and text display output, for example to
prompt for bootflags [-s, kernel name, etc].

>> The secondary loader must then load the kernel from /netbsd.
>> I think it's reasonable to require that the root fylesystem
>> is of type ffs, so that would be the only filesystem type
>> the loader must understand.
>At this point the ufsboot code for one of the other systems might
>be of interest.
> 
>> > The loader should also checkout the hardware config.

The loader should check out as little as possible, to allow for
maximum flexibility.  The kernel should do as much as possible.

>> I hope so. Basically we need a very much stripped down ffs
>> driver, allowing us to read a file in the root directory.
>Subdirectories are quite handy too. I don want too much stuff in my
>root directory.

Hmmm ... I believe that we shouldn't make it too complicated there.  A
simple working boot loader that pulls in /netbsd would be a great step
forward.  Decorations can come later 8-)



Cheers -- Volker
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Chirac -- Le fossoyeur de la Grande Nation 		Volker A. Brandt
Internet: volker@iam.uni-bonn.de			Angewandte Mathematik
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