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Re: request for help to make powerpc custom boot disks



On Fri, Oct 12, 2001 at 09:27:22AM +0200, Michael Schmitz wrote:
> It won't be necessary - 1) only works on machines that have OF support for
> booting from CD I think. With no requirement for MacOS drivers on
> floppies, we can load a bootstrap from floppy directly.

OpenFirmware != MacOSROM

miboot is a MacOSROM based bootloader NOT an OpenFirmware one.

the MacOSROM can read CDs, but declares them irrelevant if they don't
have a MacOS driver partititon that it can load to replace its burned
in broken ones. 

the boot-floppies boot-hfs floppy does NOT use OF,it uses the
MacOSROM, which doesn't require a driver partition on a floppy. 

> Booting from CDs on the old machines might work the way you describe if
> all that OF asks is to run driver_init. From what I've seen discussed

OF is not asking for the driver partitions and knows nothing about
them nor cares if they exist, the problem is getting OF to read CDs AT
ALL.  generally it can't, or does so in such an unreliable way as to
be worthless.  you also have to tell OF to boot anything but the
MacOSROM directly on the command line, which by default (and often is
only capable) of being fed to a serial terminal.

> before that's not the case (you need the CD drivers and a fake system file
> to get the MacOS ROM even load your stuff from CD).

OF never reads any disk, or medium, it simply passes control to MacOS
ROM immediatly, thats why boot-device is /AAPL,ROM (thats not a disk,
thats the OF device-tree path to the ROM).  thats why apple didn't
bother to make it able to read disks reliably, Apple's rule for OF
development is: `if we don't use it atm, we don't bother to code it
properly nor test it, nor give a damn if it works at all'

at the time apple was not using OF to read the disk, much less a CD,
thus OldWorld OF generally can't read disks very well, if at all.

-- 
Ethan Benson
http://www.alaska.net/~erbenson/

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