[openfirmware] Using Open Firmware as a boot manager

Mark Morgan Lloyd markMLl.openfirmware at telemetry.co.uk
Sat Mar 19 19:46:34 CET 2011

Thanks Mitch, noted.

Mitch Bradley wrote:
> One problem you might be having is that OFW and Linux probably disagree 
> about partition numbering in the face of extended partitions.  OFW does 
> a depth-first recursion, counting only the leaf nodes.  Conversely, at 
> least according to the example above, Linux does a breadth-first 
> recursion and appears to count the intermediate nodes (extended entries) 
> as first-class partitions.
> Given the layout above, here is my swag at how the numbering works. 
> Indentation represents inclusion in an extended partition.
>   hda1 - OFW 1
>   hda2 - (OFW doesn't count this as a selectable device)
>     hda5 - OFW 2
>     hda6 - OFW 3
>   hda3 - OFW 4
> I tend to format disks using only primary partitions, just to keep 
> things simple.
> Linux's largely-unwritten policies for numbering disks and other devices 
> have been a source of confusion forever.

I'm very suspicious about the partition layout in the example I cited, 
which is the result of running DOS fdisk followed by Linux fdisk- I 
normally try to only run one fdisk implementation per drive. It looked 
badly out of order to me, but Linux's fdisk didn't think it needed 
correcting. So I agree with your unease about Linux's general behaviour, 
and I'm sure that I needn't comment about the way that unlike MS OSes it 
doesn't leave a gap between the partition table and filesystem.

Thanks very much for all your help. I'll be back.

Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]

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