At 6:17 PM -0500 2/26/99, Hauke Fath wrote:

>-- why not simply fire up the Device Manager, access .Sony and read in the
>kernel? Why would you want to use a _NetBSD_ device driver in that
>situation? There is no kernel running at that moment, is there? Or, what
>important detail am I missing?

Yes! I envision a boot process working like this:

1. The ROMs do diagnostics, basic hardware init, some basic MacOS services
are initialized (like the slot manager) A-Traps are setup, NuBus Primary
init occurs.

2. The system loads in the first four blocks of the first bootable disk it
finds, sees that its executable and then runs the executable.

Four blocks is relatively large for assembly but if we want to throw a dialog
on the screen or do network booting or something we'll need more code than
can fit in 4 boot-blocks. So the first stage loads in a second stage from
the blocks that follow the boot-blocks.

3. The second stage has enough code to search the floppy/SCSI chain for a
NetBSD partition or it is statically rigged to load from a pre-determined
spot (like lilo in the olden days).

4. The booter then jumps to the kernel and NetBSD runs.

All of the above items should be able to happen relying stricly on ROM code.

The nice thing about this is that all the code and the partition/disk
image can be created entirely in NetBSD. No Mac/OS help necessary.

Also, keep in mind, we don't even need to pretend that we're using HFS for
the disk. Only the format of the boot-blocks needs to conform to the HFS
spec for boot-blocks. The structure of the rest of the partition/disk can
be laid out any way we want.

The trick is to find out what the minimal set of ROM routines is. The SE/30
or Classic II is a likely candidate. Take a look at the ROM description file
for available routines and A-Traps and then have a look at the ROM resource
for the drivers that are built in. That's probably .Sony

_______________________________________________________________________
 Michael Zucca - mrz5149@acm.org - http://www.mdc.net/~mrz5149/
 "I will choose a path that's clear. I will choose Freewill. "
  --Rush, Freewill
_______________________________________________________________________