Re: Test-DFS for PowerPC

[Sven Luther <sven.luther@wanadoo.fr>]

On Sat, Jun 05, 2004 at 10:38:35AM -0700, Brad Boyer wrote:
> On Sat, Jun 05, 2004 at 04:36:00PM +0200, Sven Luther wrote:
> > On Sat, Jun 05, 2004 at 10:58:25AM +0200, Robert Jordens wrote:
> > > [Sat, 05 Jun 2004] Sven Luther wrote:
> > > > Also, i doubt it will work out of the box on old world, Robert, what is
> > > > the kernel size, and could you include a miboot image of this if it is
> > > > small enough ? Not sure the kernel or initrd fit on a floppy though.
> > > 
> > > Could you help me with that? I neither have the hardware nor the
> > > experience.
> > 
> > Well, you would need to use the powerpc-small kernel, and build an
> > initrd which include some additional modules and which loads them, and
> > that this initrd fits on on a floppy (compressed). What size has the
> > initrd right now ? 
> 
> If only it were that simple. In order to boot mac-style on an old world
> model, the ROM has to recognize your image as a valid, Mac boot system,
> which requires more than just a blessed HFS volume.
> 
> The boot process on an old world Mac looks something like this:
> 
> 1) power-on
> 2) load OF
> 3) boot from default boot-device (/AAPL,ROM)
> 4) load and run Mac ROM code
> 5) look for bootable device (first from setting in PRAM, then a search)
> 6) load the drivers for the device (floppy: in ROM, CD/HD: driver partitions)
> 7) load and run system file from blessed folder
> 
> The problem is step 6. There isn't a freely available driver, so we can't
> put one on a Debian install CD. Apple did document it enough to write one,
> but I know I don't have the time for that, since I have a pretty big list
> of stuff I'd rather write.
> 
> And just in case you're wondering, on an old world Mac, the 'c' key to
> force CD boot is implemented in the Apple ROM, not OF like in new world.

Which is why, on oldworld, you boot from a miboot floppy. For that you
need a kernel, such as the powerpc-small one, which will fit on a floppy
together with miboot (so a kernel of around 1200K compressed), and then
put an initrd on the second floppy, which will load the appropriate
modules to mount the cdrom. This is how the oldworld debian installation
has been done since times imemorial, and how it happens right now also.

So, boot sequence is : 

1) put miboot floppy in floppy drive
2) power on
3) miboot gets loaded
4) it launches the kernel, asks for a root fs.
5) you plugin the root floppy.
6) you are happily running linux thereafter.

Well, there is also the bootx method, but that somehow defeats the
purpose of a rescue CD.

Robert, could you please add the code to generate the non pmac images
also ? You need :

  1) access to the vmlinux kernel (i suppose you get it from the
  kernel-image-2.6.6-powerpc, right ?).
  2) access to the initrd.
  3) access to /usr/lib/kernel-image-2.6.6-powerpc content.
  4) install mkvmlinuz (from the unstable mkvmlinuz package).
  5) mkvmlinuz -a chrp -o dfs_kernel-chrp -k /path/to/kernel/vmlinux-2.6.6-powerpc \
  	-d /usr/lib/kernel-image-2.6.6-powerpc -i /path/to/initrd
  6) move dfs_kernel-chrp to the boot dir.

And voila, you have a booting chrp and chrp-rs6k kernel.

(Well, provided the initrd includes the necessary modules for it
naturally.).

Also, do you have also the sources of the modified powerpc packages ? 

And finally, i have 0.6.4-rj3, and it refuses to boot on my ibook,
either by using the c key or by launching yaboot from the OF. IT speaks
about MAC-PART or something such not finding a filesystem.

BTW, where does the kernel on the iso comes from ? 


Friendly,

Sven Luther