Re: hfs boot floppy versions

[Christian Müller <cmue81@gmx.de>]

> On Mon, Oct 31, 2005 at 03:00:39AM +0100, Christian Müller wrote:
>  
>
> > > That is beside the point. The miboot stuff wasn't included for legal 
> > > reasons,
> > > and i don't even understand why it was included in woody.
> > >     
> >
> > Yep, remember reading that somewhere - would it be possible to take 
> > the NetBSD code producing ofwboot.xcf, legal-wise or is it also 
> > unfree in the debian terms?
> >   
>
>
> No  idea of what that even is, could you describe it and provide a 
> pointer to
> it ?
The idea:
* http://ezine.daemonnews.org/200009/sb.html  gives a technical 
oversight, pretty scsi-centric though - the boot stages netbsd uses are 
described thoroughly though - there's also a nice figure that 
illustrates things, but the image quality is horrible.  They still work 
with a load-base of 4000, after SystemDisk patches are applied it's 
600000.  After all, the article is from 2000, things may have changed.

Other links of interest:
* 
ftp://ftp.netbsd.org/pub/NetBSD/NetBSD-2.0.2/macppc/INSTALL.html#Available%20Boot%20Media 
(explains "partition zero" boot approach which results in the 3stage 
process depicted above and a 2stage process where OpenFirmware looks 
itself for ofwboot.xcf on partitions it is capable of reading)
* 
ftp://ftp.netbsd.org/pub/NetBSD/NetBSD-2.0.2/macppc/INSTALL.html#Open%20Firmware%20boot%20syntax 

* http://www.netbsd.org/Ports/macppc/faq.html   (lengthy faq)
* http://netbsd.gw.com/cgi-bin/man-cgi?ofwboot+8.macppc+NetBSD-current 
(ofwboot manpage)
* 
http://netbsd.gw.com/cgi-bin/man-cgi?installboot+8.macppc+NetBSD-current 
(installboot manpage)

The ofwboot manpage tells where 3-stage and 2-stage boot-process meet:

   ofwboot      *ofwboot* is installed via installboot(8) 
<http://netbsd.gw.com/cgi-bin/man-cgi?installboot+8.macppc+NetBSD-current> 
on systems with Open
                Firmware versions less than 3.  It is not necessary to 
spec-
                ify this file name, as it is stored in a special 
location on
                the disk, partition ``zero''.  For example, the following
                command might be used to boot from a SCSI device with 
ID 2:
                *0 >boot scsi-int/sd@2:0*.

   ofwboot.xcf  *ofwboot.xcf* is in XCOFF format.  This file is used on 
all
                Open Firmware 3 systems, and on Open Firmware systems 
prior
                to 3 when the bootloader is not installed in partition
                ``zero'', such as from an ISO-9660 format CD-ROM.


* http://www.netbsd.org/Ports/macppc/SystemDisk-tutorial/ (NetBSD also 
messes with real-base, sure they will have their reasons, but it will 
make a dual boot machine to a classic mac os uncomfortable - though mac 
os boots with the tampered with real-base, but resets it to default.  
i've read about systems prior to the beige G3 that reset many more of 
the boot variables to defaults <- maybe hack a forth script into nvram 
named bootlinux/bootbsd that sets proper variables and afterwards does 0 
bootr if there is space in nvram for own forth functions <- are they 
kept like varaibles I set??)

So in theory, I should be apple to boot it via OpenFirmware and 
ofwboot.xcf on a filesystem OF understands (2stage) or by putting it at 
load-base in partition zero (3stage).

I had trouble with the partition zero method, but I actually did manage 
with a 2.4 OpenFirmware to fetch ofwboot.xcf from a iso9660 style cd.  
It loads properly, greets with "NetBSD/macppc OpenFirmware Boot 1.10" - 
it then asks for a kernel to boot, that's where I got stuck again.  
Either I did not find the right format+path to tell him where to look 
for the kernel (doc says OpenFirmware-Style path, but with "/" as 
opposed to "\" to separate directories in a path) or it does not work at 
this point (speaking for the Beige G3 I'm testing with, of course).  It 
might be that this is just unsupported for OFs < 3.

I *think* it is a size-issue that the NetBSD team uses ofwboot.xcf 
instead of using one big xcoff-kernel-image, speculating though.   
Somewhere I read a post saying that it might be possible to load a 
vmlinuz.xcoff directly via OpenFirmware command (which would render the 
extra ofwboot.xcf NetBSD uses pointless), I did not succeed in doing 
so.  I tried it with boot-devie set to 
ide1/@0:,\INSTALL\POWERPC\VMLIN001.INI - if someone succeeded with 
something like this, please come forward =).

Just thinking aloud:  How difficult would it be to prepare a floppy that 
would simply boot a cd?  My understanding, might be wrong, is that this 
is the case with isolinux where the "boot-floppy" is fetched via 
el-torito into RAM and then goes from there to start a bloated system.  
Wouldn't it be possible to let :something: like isolinux boot from a 
real floppy on those oldworlds which is then responsible for getting a 
bootable cd up and running - ideally this :something: would really only 
just be enough to let cds boot which would have booted on macs with OF 
3+ without any help.  A helper disk based on miboot, so to speak.  This 
way installer teams on all distributions just have to focus on providing 
OF3 bootable cds - if it were not for the legal problems of miboot and 
those macs that don't have a cd-drive =).

Doing it fool-proof "partition zero"-wise is also not easy to do.  One 
is faced with different load-base settings, so you would have to know 
prior to loading the loader where to put it - work-around might be more 
than one entry-point for the code, at 4000, 600000, etc.  But this is 
too much of hazzle for hardware that's, basically, obsolete *no-nag*.


So long,
Christian

ps: btw, sorry for the personal mails, they account to me being lazy and 
lame using the overly simple reply button :)